I recently read a complaint by an EV driver that the charging station at De Anza College cost 55 cents/kwh. The national average price for electricity is around 10 cents, and at that price a typical electric car costs under 3 cents/mile for electricity. Gasoline costs about 8 cents/mile in a Prius, about 13 cents in a decent non-hybrid and 18 cents/mile in the average car which gets 22mpg. (At least here in California.) But the college’s charger’s electricity is almost 15 cents/mile in most electric sedans today, which is more than the gasoline in any gasoline car an eco-conscious person is likely to buy. (California Tier III electricity is 30 cents/kwh and thus almost as much.)
The price of charging stations varies wildly. A lot of them are free still, financed by other motivations. Tesla’s superchargers are free — effectively part of the cost of the car. It’s not uncommon for parking lots to offer free charging if you pay for parking, since parking tends to cost a fair bit more. After all, you won’t put more than 20kwh in a Leaf (and probably a lot less) and that costs just $2 at the average grid price.
This got me thinking of how the economics of charging will work in the future when electric cars and charging stations are modestly plentiful. While the national grid average is 10 cents, in many places heavy users can pay a lot more, though there are currently special deals to promote electric cars. Often the daytime cost for commercial customers is quite a bit higher, while the night is much lower. Charging stations at offices and shops will do mostly day charging; ones in homes and hotels will do night charging.
Unlike gasoline pumping, which takes 5 minutes, charging also involves parking. This is not just because charging takes several hours, but because that is enough time that customers won’t want to come and move their car once full, and so they will take the space for their full parking duration, which may be 8 or more hours.
Charging stations are all very different in utility. While every gasoline station near your route is pretty much equivalent to you, your charging station is your parking spot, and as such only the ones very close to your destination are suitable. While a cheap gas station 2 miles off your route would have a line around the block, a free charging stations 2 miles away from your destination is not that attractive! More to the point, the charging point close to your destination is able to command a serious premium. That have a sort of monopoly (until charging stations become super common) on charging at the only location of value to you.
Put another way, when buying gasoline, I can choose from all the stations in town. When picking an EV charge, I can only choose from stations with an available spot a short walk from my destination. Such a monopoly will lead to high prices in a market where the stations are charging (in dollars :-) what the market will bear.
The market will bear a lot. While the electricity may be available cheap, EV owners might be easily talked into paying as much for electricity as gasoline buyers do, on a per-mile basis. The EV owners will be forgetting the economics of the electric car — you pay the vast bulk of your costs up front for the battery, and the electrical costs are intended to be minor. If the electricity cost rivals that of gasoline, the battery cost is now completely extra.
Naturally, EV owners will do at least half their charging at home, where they negotiate the best rate. But this could be worse, as they might well be talked into looking at the average. They could pay 80 cents/kwh in the parking lot and 10 cents/kwh at home, and figure they are getting away with 45 cents and “still beating gasoline.” They would be fooling themselves, but the more people willing to fool themselves, the higher prices will go.
There is another lack of choice here. For many EV drivers, charging is not optional. Unless they have easy range to get back home or to another charging place they will spend lots of time, you must charge if you are low and the time opportunity presents itself. To not do so is either impossible (you won’t get home) or very foolish (you constrain what your EV can do.) When you face a situation where you must charge, and you must charge in a particular place, the potential for price gouging becomes serious. read more »
But I do believe in the idea of the self-driving electric taxi as the best answer for our future urban transportation. So how do you make it happen?
There’s a big problem with this vision. Electric cars today have perhaps 100 to 150 miles of range, which means 3 to 6 hours of operation, depending on the speeds you go. You can make more range (like a Telsa S) but only by adding a lot of weight and cost. But an effective taxi is on shift all day, or at least all the waking hours, and could easily operate 8 to 10 hours per day. While any taxi will have downtime during the day (particularly at off-peak hours) the recharge of the battery takes so long it’s hard to do during the day. Ideally you want to charge at night, when power is cheap. So let’s consider the options.
Large battery pack
You could make a vehicle with enough battery for a full day’s work, and charge it at night. This is very expensive today, and also takes a lot of room and weight in the vehicle, reducing its efficiency. You also need taxis at night so either way you have to have some taxis that work at night and recharge in the day, but not as many.
While battery swap did not pan out for Better Place, it actually makes much more sense for a robotic taxi fleet. You just need a few swap stations in the city. It doesn’t bother the robots if they take a while for a swap (mainly it bothers you because you need more stations.) And while humans would get very angry if they came to the swap station and saw they were 4th in line at 5 minutes/swap, robots would just schedule their swaps and get in and get out.
That’s all good, and it solves a few other problems. Taxis will be putting on lots of miles every day, and they will probably wear out their battery quickly. If the rest of the vehicle has not worn out, swap becomes ideal — replace the vehicle’s components when you need to, including the most expensive part, the battery. It also makes it easier to charge all batteries only at night, on cheap baseload power.
Swap also allows the batteries to be only used in the “easy” part of their duty cycle (from 80% to 20%) without much hassle. You only get 60% of the range, but you don’t care a lot, other than in having to
buy more battery packs. You just do the math on what’s cheaper.
A working supercharger that can recharge a vehicle in an hour solves the problem as well. Robotic taxis can always find a spare hour without much loss of efficiency. (Indeed with none as they will age by active mile or hour.) The big problem is that supercharging generally is felt to stress the batteries and reduce the lifetime of the packs. Certainly running a car on full cycle every day and supercharging it is not going to produce a happy battery.
A robocar supercharging station could do a few extra things, though. For example, you could hook the car up to a special cooling system to pump externally chilled coolant through the batteries, as heat is the big killer in the supercharge. You might even find a way to put some pressure in to keep the cases from expanding that much, as this is a big stressor when charging.
Supercharging probably has to be done in the day, with more expensive power. One charge for the morning peak and another for the evening. Some speculate it’s worth using your inventory of old battery packs to store power during the night to release in the day. Solar can also help during the day — on sunny days, at least.
While automated connection is good, you really would not have many supercharging centers, due to their high power needs, so they could have human staff to do the work.
Both the supercharging and battery swap stations do not need to be located all that conveniently for humans. Instead, you can put them near power substations where megawatts can be purchased.
More vehicles and ordinary L2 charging
If the batteries are more expensive than the vehicles, then perhaps just having more vehicles to house all your battery packs is the answer. Then you have vehicles spending their time idle, and charging at ordinary level 2 (6kw) rates. Full level 2 can add about 20 miles of range to a car like a Leaf in an hour. Depending on the usage patterns that might not be too bad. Of course it’s daytime power again, which is expensive. Urban taxis won’t go more than about 25mph on average if they are lucky, often less, particularly at rush hour. Suburban will go a bit faster. You need stations that allow a robot to recharge, which could mean inductive, or human-staffed, or eventual robotic plug-in systems. Don’t laugh at the idea of human-staffed. The robot will not be in a super rush, so stations near retail shops or existing gas stations would work fine as long as somebody can come out and tend to the robot on connect and disconnect within 5 minutes.
It may seem like more vehicles is more expensive, but that’s not necessarily true. It depends on how and why the vehicles wear out. Ideally you design the vehicle so battery and most major vehicle components all reach end-of-life at a similar time or that they can be replaced easily. That may mean a battery that can be swapped — but in the shop, not at an automatic swap station.
Plug in hybrids?
Plug in hybrids of course solve the problem, and they can charge when they can to be mostly electric and only use that gas engine more rarely. This actually creates a downside — it’s expensive to have a fossil fuel power train around to barely use it. And it adds a fair bit to the maintenance cost. This does allow for highway travel. Otherwise, you send a liquid fuel car to anybody wanting to do a long highway trip - save the electrics for the urban travel.
Very light vehicles
Today’s electrics use about 250 to 300 watt-hours/mile. OK, but not great. Efficient designs can go below 100 watt/hours per mile. That means doing 300 miles, which is enough for a full day in a city cab, needs only 30kwh (probably a 45kwh battery.) That’s a $22K battery today, but it will be a $9K battery by the end of this decade according to predictions. This might be quite reasonable.
Last year, I met Oliver Kuttner, who led the team to win the Progressive X-Prize to build the most efficient and practical car over 100mpg. Oliver’s Edison2 team won with the VLC (Very Light Car) and surprised everybody by doing it with a liquid fuel engine. There was a huge expectation that an electric car would win the prize, and in fact the rules had been laid out to almost assure it, granting electric cars an advantage over gasoline that I thought was not appropriate.
The Edison2 team made their focus on weight, though they far from ignored drag. Everybody made an aerodynamic car, but what they realized was that making the car light was key. And batteries are heavy, heavier than efficient liquid fuel engines. Hybrid systems, with both batteries and two motors are even heavier than what they built. They also developed a new type of suspension which was much lighter and allowed a simpler car.
Since the X prize, they have built electric cars as well — their techniques still work there, even if that’s not where they found the greatest X-prize results — and recently showed of their latest 1,400lb model which seats 4. (Though I can’t say I think it’s comfortable with 4.) Equally impressive, Oliver reports they have done succesful forward offset collision tests, and done well at them, contradicting a popular impression that small, light cars must be death traps on the road.
This bodes well for robocars. As I wrote 2 weeks ago, I think the small, light car is the future of transportation if we want it to be efficient, and the robocar can, by delivering such vehicles for people making shorter solo or 2 person trips — ie. the vast majority of all trips — make this happen.
Earlier, I brought Oliver in to give a talk at Google in the Greeen@Google series. Here is a video where I host him describing the car and their thinking around it. His thinking on cars is fresh and while it’s very challenging to start a new car company, here’s somebody who might just do it.
We’ve often said that in the most distant future, when car accidents are very rare, we will be able to make our cars lighter because over 30% of the weight of a modern vehicle goes into safety features. I think we can get those light vehicles even sooner.
You’ve probably seen the battle going on between Elon Musk of Tesla and the New York Times over the strongly negative review the NYT made of a long road trip in a Model S. The reviewer ran out of charge and had a very rough trip with lots of range anxiety. The data logs published by Tesla show he made a number of mistakes, didn’t follow some instructions on speed and heat and could have pulled off the road trip if he had done it right.
Both sides are right, though. Tesla has made it possible to do the road trip in the Model S, but they haven’t made it easy. It’s possible to screw it up, and instructions to go slow and keep the heater low are not ones people want to take. 40 minute supercharges are still pretty long, they are not good for the battery and it’s hard to believe that they scale since they take so long. While Better Place’s battery swap provides a tolerable 5 minute swap, it also presents scaling issues —
you don’t want to show up at a station that does 5 minute swaps and be 6th in line.
The Tesla Model S is an amazing car, hugely fun to drive and zippy, cool on the inside and high tech. Driving around a large metro area can be done without range anxiety, which is great. I would love to have one — I just love $85K more. But a long road trip, particularly on a cold day? There are better choices. (And in the Robocar world when you can get cars delivered, you will get the right car for your trip delivered.)
Electric cars have a number of worthwhile advantages, and as battery technologies improve they will come into their own. But let’s consider the economics of a long range electric. The Tesla Model S comes in 3 levels, and there is a $20,000 difference between the 40khw 160 mile version and the 85kwh 300 mile version. It’s a $35K difference if you want the performance package.
The unspoken secret of electric cars is that while you can get the electricity for the model S for just 3 cents/mile at national grid average prices (compared to 12 cents/mile for gasoline in a 30mpg car and 7 cents/mile in a 50mpg hybrid) this is not the full story. You also pay, as you can see, a lot for the battery. There are conflicting reports on how long a battery pack will last you (and that in turn varies on how you use and abuse it.) If we take the battery lifetime at 150,000 miles — which is more than most give it — you can see that the extra 45kwh add-on in the Tesla for $20K is costing about 13 cents/mile. The whole battery pack in the 85kwh Telsa, at $42K estimated, is costing a whopping 28 cents/mile for depreciation.
Here’s a yikes. At a 5% interest rate, you’re paying $2,100 a year in interest on the $42,000 Tesla S 85kwh battery pack. If you go the national average 12,000 miles/year that’s 17.5 cents/mile just for interest on the battery. Not counting vehicle or battery life. Add interest, depreciation and electricity and it’s just under 40 cents/mile — similar to a 10mpg Hummer H2. (I bet most Tesla Model S owners do more than that average 12K miles/year, which improves this.)
In other words, the cost of the battery dwarfs the cost of the electricity, and sadly it also dwarfs the cost of gasoline in most cars. With an electric car, you are effectively paying most of your fuel costs up front. You may also be adding home charging station costs. This helps us learn how much cheaper we must make the battery.
It’s a bit easier in the Nissan LEAF, whose 24kwh battery pack is estimated to cost about $15,000. Here if it lasts 150K miles we have 10 cents/mile plus the electricity, for a total cost of 13 cents/mile which competes with gasoline cars, though adding interest it’s 19 cents/mile — which does not compete. As a plus, the electric car is simpler and should need less maintenance. (Of course with as much as $10,000 in tax credits, that battery pack can be a reasonable purchase, at taxpayer expense.) A typical gasoline car spends about 5 cents/mile on non-tire maintenance.
This math changes a lot with the actual battery life, and many people are estimating that battery lives will be worse than 150K miles and others are estimating more. The larger your battery pack and the less often you fully use it, the longer it lasts. The average car doesn’t last a lot more than 150k miles, at least outside of California.
The problem with range anxiety becomes more clear. The 85kwh Tesla lets you do your daily driving around your city with no range anxiety. That’s great. But to get that you buy a huge battery pack. But you only use that extra range rarely, though you spend a lot to get it. Most trips can actually be handled by the 70 mile range Leaf, though with some anxiety. You only need all that extra battery for those occasional longer trips. You spend a lot of extra money just to use the range from time to time. read more »
One of my first rules of robocars is “you don’t change the infrastructure.” Changing infrastructure is very hard, very expensive, requires buy-in from all sorts of parties who are slow to make decisions, and even if you do change it, you then have a functionality that only works in the places you have managed to change it. New infrastructure takes many decades — even centuries, to become truly ubiquitous.
That’s why robocar enthusiasts have been skeptical of things like ITS plans for roadside to vehicle and vehicle to vehicle communications, plans for dedicated highway lanes with special markers, and for PRT which needs newly built guideways. You have to work with what you have.
There are some ways to bend this rule. Some infrastructure changes are not too hard — they might just require something as simple and cheap as repainting. Some new infrastructures might be optional — they make things better in the places you put them, but they are not necessary to operations. Some might focus on specific problem areas — like special infrastructure in heavy pedestrian areas or parking lots, enabling or improving optional forms of operation in those areas.
Another possiblility is to have robocars enable a form of new infrastucture, turning it upside down. The infrastructure might need the robocars rather than the other way around. I wrote about that sort of plan when discussing a solar panel on a robocar.
A recent proposal from Siemens calls for having overhead electric wires for trucks. Trolley buses and trams use overhead electric wires, and there are hybrid trolley buses (like the Boston T line) which can run either on the wires or on an internal diesel. These trucks are of that type. The main plan for this is to put overhead wires in things like shipping ports, where trucks are running around all the time, and they would benefit greatly from this.
I’ve seen many proposals for electrication of the roads. Overhead wires are problematic because they need to be high enough to go over the trucks and other high vehicles, but that makes them harder to reach by low vehicles. You need two wires and must get good contact. They are also damn ugly. This has lead to proposals for inductive power supplies buried in the road. This is very expensive as it requires tearing up the road. There are also inductive losses, and while you don’t need to make contact, precise driving is important for efficiency. In these schemes, battery-electric cars would be able to avoid using their batteries (and in fact charge them) while on the highway, vastly increasing their range and utility.
Robocars offer highly precise driving. This would make it easier to line up on overhead wires or inductive coils in the road. It even would make it possible to connect with rails in the roadbed, though right now people don’t want to consider having a high voltage rail on the ground, even on a highway.
It was proposed to me (I’m trying to remember by who — my apologies) that one new option would be a rail on the side of the highway. This lane would be right up against the guardrail, and normally would be the shoulder. In the guardrail would be power rails, and a connector would come from the left side of the vehicle. Only a robot would be able to drive so precisely as to do this safely. Even with a long pole and more distance I am not sure people would enjoy trying to drive like this. A grounding rail in the roadbed might also be an option — though again tearing up the roadbed is very expensive to do and maintain.
There is still the problem of having a live rail or wire at reachable height. The system might be built with an enclosed master cable and then segments of live wire which are only live when a vehicle is passing by them. Obviously a person doesn’t want to be there when a car is zooming through. This requires roboust switching eqiupment for the thousands of watts one wishes to transfer. You also have to face the potential that a car from the regular lanes could crash into the rail and wires, and while that’s never going to be safe you don’t want to make it worse. You also need switching if you are going to have accounting, so only those who pay for it get power. (Alternately it could be sold by a subscription so you don’t account for the usage and you identify cars that don’t have a subscriber tag who are sucking juice and fine them.)
There is also the problem that this removes the shoulder which provides safety to other cars and provides a breakdown lane. If a vehicle does have to stop in this lane for emergency reasons, sensors in the rail could make sure that all robocars would know and leave the lane with plenty of margin. They would all have batteries or engines and be able to operate off the power — indeed the power lines need not be continuous, you don’t have to build them in sections of the road where it’s difficult. If other cars are allowed to enter the lane, it must not be dangerous other than physically for them to brush the wires.
It’s also possible that the rail could be inductive. The robocar could drive and keep its inductor contact just a short distance from the coils in the rail. This is more expensive than direct contact, and not as efficient, but it’s a lot cheaper than burying inductors in the roadbed. It’s safe for pedestrians and most impacts, and while a hard impact could expose conductors, a ground fault circuit could interrupt the power. Indeed, because all vehicles on the line will have alternate power, interruption in the event of any current not returning along the return is a reasonable strategy.
For commuters with electric cars, there is a big win. You can get by with far less battery and still go electric. The battery costs a lot of money — more than enough to justify the cost of installing the connection equipment. And having less battery means less weight, and that’s the big win for everybody, as you make the vehicles more efficient when you cut out that weight. Of course, if this lane is only for use by electrified robocars, it becomes a big incentive to get one just to use the special lane.
The power requirements are not small. Cars will want 20kw to go at highway speed, and trucks a lot more. This makes it hard to offer charging as well as operating current, but smaller cars might be able to get a decent charge while driving.
Update: When I first wrote this, I was under the mistaken belief that Better Place only swapped one type of battery module. At present they only support one, but their swap stations are designed to support up to six kinds, as long as they can be loaded and unloaded from below.
Recently, electric car battery-swap company Better Place announced delivery of their first cars in Israel. Israel is a country of small size where it makes sense to deploy a technology like this with a chicken and egg problem. They hope to have enough battery swap stations that people feel they can drive an electric car and refuel it as quickly and conveniently as a gasoline buggy.
I remain skeptical about battery swap for electric cars, but think robocars solve many of those problems. Here’s why:
To have a workable battery swap system, you need to standardize the battery module, ideally having just one or two form factors and electrical characteristics. Just one to start, in fact. This has many downsides:
A large part of the innovation in electric cars today is in the batteries. A big part of what Tesla did was their new cooling system. Designers all want to be able to play with chemistries, voltage, controllers and more. They might give up playing with size and placement but not those things.
It’s still an issue to not be able to vary size and shape of the battery, at least for people wanting to build cars of unusual shape.
A large part of the cost of an electric car today is the battery. With the swap system, you can’t buy the battery with the car. You get whatever battery you are swapped. That’s good in some ways, but eliminates open market competition on these systems because there is only one buyer — the swap company.
Swap machines are expensive, take land and still take five minutes, arrival to departure. That’s almost as quick as filling up with gas, but a typical gas station has 8 pumps, and some have many more. If there are several cars in line at a single swap station, you’re in for a serious wait.
On the plus side, people actually need swaps more rarely than they imagine. A 70-100 mile range car will hardly ever feel the need for a swap — in many ways the availability of the swap makes you feel more comfortable about the car, even if you rarely use it. It’s better than the level 3 charge which can damage the battery and still takes 15-20 minutes.
I think robocars (cars able to move while empty to the swap station) solve many of these problems. They solve them because while robocars (particularly those operating as taxis) need to run all day and thus want to swap batteries, the cars can move to the swap station on their own, when they are not serving somebody.
There is much less need to standardize, though it does help. Your car simply goes to a swap station that has its type of battery available.
While it wastes energy and a little time, it doesn’t bother the robot to have to go a few miles to find such a station. You don’t need one on every popular route.
The robot can schedule an appointment for a swap if need be. Not that it really minds waiting a lot, unless it has a job to do. But with a scheduled swap it might even do one while carrying a passenger, if it happens to be passing a swap station and can book a no-wait appointment for the time it will be passing, and the passenger doesn’t mind the 3 minute stop.
Most typically, this will be used by taxi fleets. Each taxi fleet can have their own swap station, for the type of battery cases they like. They can program their taxis to take jobs that bring them closer to the swap station when they will be running low. You can get buy with just one swap station for the whole fleet, or perhaps just a few. The taxi fleet can have a mixture of cars of different swap types and cars without swap ability. The latter can’t run all day and must spend time in charging stations as planned.
With robocars, you can solve range problems not by swaping the battery, but by swapping the car. If you have a car that is running low, it can stop in a convenient lot to have you switch quickly to a taxi with lots of charge. Then the car you were in can head off for charge or swap in no paticular rush.
By allowing lots of types of battery form factors and swap stations, you allow innovation and competition in these areas, which in the long run is a win for the customer. Anything that blocks competition may sound good at first but quickly bogs things down.
Now I still want to credit Better Place for working to solve the range and range anxiety problems of electric cars. There will still be competition because I don’t expect all electric car vendors to want to be compatible with their system. But I think their technology comes into its own best when the cars can worry about the swap rather than the drivers.
I often see people say they would like to see solar panels on electric cars, inspired by the solar-electric cars in the challenge races, and by the idea that the solar panel will provide some recharging for the car while it is running and without need to plug it in.
It turns out this isn’t a tremendously good idea for a variety of reasons:
You’re probably not going to get more than a couple hundred watts of PV peak power on a car with typical cells. Even properly mounted on a roof in a sunny place like California, each peak watt delivers an average of about 5 watt-hours in a day, so 200 watts gives you 1kw-h. That’s good for around 4 to 6 miles on today’s electric cars. Not a huge range boost.
While thin film panels don’t weigh a lot the power they provide during actual driving would normally be only a minor boost. My math suggests they weigh more than the battery for the power they will provide while operating.
Panels on a car will instead be mounted flat, cutting about 30% of their output. Normally you want to tilt to the angle of the sun.
Cars are often in the shade, even parked indoors. Unless you work to pick your parking to have sun all day, you’ll only get a fraction of the power.
If you do leave your car in the sun, in many places that means it will get quite hot, you’ll burn up some of the solar energy cooling it down. (Indeed, the solar panels sometimes found on today’s hybrids and EVs don’t charge the battery, they just run a cooling fan.)
The worst one: If your battery is not somewhat discharged, it doesn’t have any place to put the solar energy, and so it is just thrown away. But due to range anxiety, people prefer their electric cars be kept full. It takes careful planning to use that energy.
A car is a very bumpy place, so you need more rugged panels than what you might put on a roof.
It is possible to get more than 200w on a car — some of the solar challenge cars that exist to be nothing but panels have gotten around a kw by using high price, high-efficiency panels. But it’s still generally much better to just put the panels on a roof where they will realize their full potential, and feed the grid, and charge from the grid.
However, on Friday I was teaching a class on the future of Robocars to my students at Singularity University and in the exercises some students wondered if they might do something for solar powered cars. (I was impressed since the students, having had only a short time to think about the issue, have to work to bring up something new.)
Robocars might solve some of the problems above, and thus possibly make sense as a place to put panels.
A robocar parks itself and can move. So one with a solar panel can move around to make sure it’s always in the sun, and that the sun is striking it from the right angle. It can’t move too far or too often without wasting some of the power, but it can do something.
When the batteries get so full that they are not making proper use of the solar energy, a robocar can find a charging station, not to charge but rather to sell excess power back to the grid and other cars. (This presumes charging stations are set up this way.)
Robocars could dock with other robocars that are more discharged and offer them the extra solar power, no charging stations involved — though fancy robotics are needed on the charging interface, or human beings who can do the connections.
If a robocar has an actuator that can tilt the panels, it can do even better. While an ordinary car could have this, an ordinary car would not have the ability to rotate in the plane of the ground to track the sun without another actuator.
It’s still not great, but it might improve things. Generally it still may be better to have the panels on rooftops and get the most from them. However, when we start thinking about super lightweight cars, cars that travel for under 100 watt-hours/mile, as well as higher efficiency panels, we might get some value if the panels are light.
It’s also expensive to install panels on top of existing facilities. Turns out that while panels are dropping below 1$/watt next year thanks to cheap Chinese capital and manufacturing, the cost of install is still over $2/watt. Cost of install on newly manufactured buildings — or cars — can be cheaper because it’s designed in from the start. The car already has the complex electrical system, while houses need to add them if they go solar.
People really are in love with the idea of a solar powered car. It’s not really possible to go green this way right now, but the future might bring something interesting.
The “burning” question for electric cars is how to compare them with gasoline. Last month I wrote about how wrong the EPA’s 99mpg number for the Nissan Leaf was, and I gave the 37mpg number you get from the Dept. of Energy’s methodology. More research shows the question is complex and messy.
So messy that the best solution is for electric cars to publish their efficiency in electric terms, which means a number like “watt-hours/mile.” The EPA measured the Leaf as about 330 watt-hours/mile (or .33 kwh/mile if you prefer.) For those who really prefer an mpg type number, so that higher is better, you would do miles/kwh.
Then you would get local power companies to publish local “kwh to gallon of gasoline” figures for the particular mix of power plants in that area. This also is not very easy, but it removes the local variation. The DoE or EPA could also come up with a national average kwh/gallon number, and car vendors could use that if they wanted, but frankly that national number is poor enough that most would not want to use it in the above-average states like California. In addition, the number in other countries is much better than in the USA.
The local mix varies a lot. Nationally it’s about 50% coal, 20% gas, 20% nuclear and 10% hydro with a smattering of other renewables. In some places, like Utah, New Mexico and many midwestern areas, it is 90% or more coal (which is bad.) In California, there is almost no coal — it’s mostly natural gas, with some nuclear, particularly in the south, and some hydro. In the Pacific Northwest, there is a dominance by hydro and electricity has far fewer emissions. (In TX, IL and NY, you can choose greener electricity providers which seems an obvious choice for the electric-car buyer.)
Understanding the local mix is a start, but there is more complexity. Let’s look at some of the different methods, staring with an executive summary for the 330 wh/mile Nissan Leaf and the national average grid: read more »
Nissan is touting that the EPA gave the new Leaf a mileage rating of 99mpg “gasoline equivalent”. What is not said in some stories (though Nissan admits it in the press release) is that this is based on the EPA rating a gallon of gasoline as equivalent to 33.7 kwh, and the EPA judging that the car only goes 73 miles on its 24kwh battery.
There is a huge problem with these numbers. If it were possible to convert perfectly, a gallon of gasoline actually has about 36kwh, so possibly the EPA is factoring in the 7% loss of electrical distribution. But in reality it isn’t even remotely possible to convert fuel to electricity perfectly.
The Department of Energy, for example, offers a number which puts under 13kwh as the energy equivalent of a gallon of gasoline. That’s how many kwh you get out of the plug if you burn coal, gas or oil with roughly the same energy as that gallon of gas. With the DoE’s number, the Leaf is getting a combined mileage of around 36 mpg-equivalent. That’s not a bad number, but there are many gasoline cars that do better than that. Even a Lexus hybrid does similar to that. This is no minor error, it’s a massive one, and it’s highly unlikely that Nissan or the EPA are unaware of it. This gives the impression of an attempt to make the Leaf seem way, way better than it is to promote electric cars. The problem with that is that when people learn the truth, they are going to be unhappy, and will be soured on electric cars, Nissan and the EPA.
Now I will agree that there is justifiable debate over the right way to do this calculation. The DoE works from its calculation of the average efficiency of power plants in the USA. People in areas with more efficient power will do better using electricity than those close to old coal plants (which are the big drag-down here.) The DoE also counts BTUs in nuclear plants (which provide about 20% of U.S. energy) as BTUs even though no fossil fuel is burned and no greenhouse gas is emitted. People must judge for themselves how “dirty” they think nuclear BTUs are, and how to value an electric car in areas where most of the electricity is nuclear. Even harder to judge are the 10% of US kwh that come from hydro. Hydro doesn’t even have BTUs or pollution, though it does come with environmental destruction. If you live in the Pacific Northwest or parts of Canada where most of the power is from hydro, you may judge the 99mpg number as more realistic, though in this case the concept of a gasoline equivalent is stretched pretty thin.
If you live in California, which burns almost no coal and gets most of its power from natural gas, and then nuclear, the real number isn’t as bad as the national average, but it’s still nowhere close to 99mpg. If you live in a place that is almost all-coal, like Utah or New Mexico, electric cars are not so great an idea — their only environmental advantage is that the fuel source is domestic rather than imported, and the coal is burned elsewhere, not right next to you.
There are other electric cars that are more efficient than the Leaf, but the big reality is that to really beat out the 50mph gasoline hybrids you need to make your car lighter.
“But wait,” some people say. We can run our electric car on solar or renewables and all is wonderful! Don’t get me started on this. There are no solar electrons. Installing renewable generation can be a good idea, but you must tie it to the grid for it to work. Not tying solar or wind or other sources to the grid is highly wasteful, because the power is discarded any time the battery is not empty (or worse, not connected.) Grid tie makes the grid greener, and people who do that can feel good about it if they do it well, but it does’t make driving more than a tiny smidgen of a percent greener than it was.
Shame on Nissan and the EPA. I hope that at least, Nissan will only sell the car in places with electricity that is well above average in quality, and refuse to sell it in places where the power is mostly from coal.
Not that I don’t understand the motivation. Had the EPA rated the car with the DoE methodology number of 36mpg, it might well have killed the car at the starting gate. It’s an interesting moral question if it’s right to lie to kickstart a technology which will become better with time. They could also have lobbied for a more reasonable but generous mpg, perhaps derived from the best natural gas plants, which would have offered a number in the 50s. Not nearly as exciting but not a car-killer, though the comparison to the Prius or Insight would not look so good.
It would have been best if they had just developed a new standard, like watt-hours/mile or miles/kwh, and leave it to the press and local power utilities to publish local conversions between “kwh” and gallons. (Not the dealers, they can’t be trusted of course.) It actually would be quite handy if every power utility were to publish, for each zone the local efficiency of the power grid in terms of BTU/kwh or greenhouse effect/kwh.
Update on Chevy Volt: The numbers for the Volt were released. As a plug-in Hybrid that can go 35 miles on its batteries and then has a gasoline engine, they rated it as 97mpg while on the battery (similar false number to the Leaf) and 37mpg while on gasoline. These numbers are actually roughly the same when using electricity at the grid national average.
Sad to say, but if you live in a place where the power comes from coal, the math seems to say you should remove most of the batteries and save the weight.
I’ve written before about solutions to “range anxiety” — the barrier to adoption of electric cars which derives from fear that the car will not have enough range and, once out of power, might take a very long time to recharge. It’s hard to compete with gasoline’s 3 minute fill-up and 300 mile ranges. Earlier I proposed an ability to quickly switch to a rental gasoline car if running out of range.
A company called EMAV has proposed a self-propelled battery trailer to solve this problem. While I am not sure how real the company is, the idea has value, particularly when it comes to robotics. As I have written, robocars can solve the “range anxiety” problem in several ways; mainly that robots don’t care about how convenient charging is, and people don’t worry about the range of a taxi beyond the current trip. But batteries are still an issue, even there.
The trailer proposal has the car hitch on the small trailer (which has room for cargo as well) and it provides the extra batteries you need when dong a long trip. The trailer is also motorized so it puts no load on the possibly small car that is “towing” it. EMAV imagines you might buy this, keep it charged, and only put it on when you need to do a long trip.
That could work, but presents a few problems. First of all, cars are much less nimble when they have a trailer on them. Backing up is much harder, and in fact novices will get completely stymied by it. You take an extra-long parking space if you can fit at all. There’s also extra drag.
We might solve the maneuvering problem a bit with a mildly robotic trailer that has a link to the car controls, making backups and turns more natural. This can be done either with steerable wheels on the trailer or just independent motor wheels which can be turned at different speeds. Such a trailer might be able to couple much more closely with the car, possibly going right on the tail so that it acts like an extension of the vehicle. This might also solve the parking problem.
Things could also be aided by making the couple and decouple very simple and easy. That’s a tall order because of safety issues, and the need for a high-current wire. The ideal would be an automatic decouple, so you could temporarily drop the trailer off somewhere if you needed to handle roads and parking where a trailer isn’t workable. Even better but harder would be an automatic recouple, obviously requiring some more sophisticated robotics in the trailer, and a fully safe coupling system.
With standardization, trailers like this could be left on lots all over a city. Anybody with a compatible electric car could, if they needed it, stop off at a convenient lot to grab a trailer. (The trailer would also be in a charging station, making automatic coupling even harder.) With the trailer grabbed there would be no range anxiety. The trailer could simply provide power, or it could go further and charge the car at high speed, allowing the trailer to be dropped off at another charging station an hour or so later. (While this sounds nice, battery chemistries may doom this plan, since you now are putting two batteries through heavy use cycles to get one unit of charge into the car, doubling the battery lifetime cost of the energy.)
While eventually trailers would need to get back to their base after one-way trips, there are lots of ways to encourage various drivers to do that. As long as the dropped
trailer is not entirely empty, you can offer drivers who take it back a ride without using their own battery, for example.
This approach might be better than the battery-swap stations planned by “A Better Place.” The Better Place battery swap is cool, but requires all cars that use it be designed around its one particular battery configuration, and that people not own their own batteries. The swap stations are expensive and land intensive, while trailer depots would require nothing but a little land and a charging station for the trailer. A special trailer hitch is a much smaller modification of a car, too.
(One variation of the “PRU” trailer has the trailer contain a diesel generator rather than a battery pack. This of course has the range of liquid fuel, and doesn’t even need a charging station where you drop it of. It’s not being particularly green when used in this fashion of course, a bit worse than a serial hybrid car. If the trailer is heavy enough it could physically push the car and not need an electrical connection to it, though people might get highly confused by steering in such situations.)
As a cheaper and more flexible version of battery swap, this approach could be good for robocars too. Robots, unlike people, will not feel too burdened by the issues of driving a vehicle with a trailer, especially if they can control the trailer’s motors or steering. Parking’s easier too, especially if they can do robotic docking and undocking. While I have written how important it is that people don’t care about the range of a taxi, the owner of a taxi cares about the duty cycle. If they robotic taxi has to spend too much of its time recharging, the return on investment is not nearly as quick. The trailer approach, like the battery swap approach, means downtime only for the batteries, not the vehicle. If the trailers are themselves simple robocars, they can move at low and safe speeds to come meet robocars that need them for a range boost. Even if not, they need not take up much space and they’re easy to scatter everywhere for quick access. Indeed, the car itself might always use a trailer and thus have only enough battery power within it to get from one trailer to the next.
Looking at new electric cars like the Nissan Leaf, we see that to keep costs down, cars with a range of 100 miles are on offer. For certain city cars, particularly in 2-car families, this should be just fine. In my particular situation, being just under 50 miles from San Francisco, this won’t work. It’s much too close to the edge, and trips there would require a full charge, and visits to other stops during the trip or finding parking with charging. Other people are resisting the electrics for lesser reasons, since if you ever do exceed the range it’s probably an 8 hour wait.
An alternative is a serial hybrid like the Chevy Volt. This has 40 miles range but a gasoline generator to provide the rest of the range and no “range anxiety.” Good, but more expensive and harder to maintain because electric cars are much simpler than gasoline cars.
Here’s an alternative: The electric car vendor should cut a deal with car rental services like ZipCar and Hertz. If you’re ever on a round trip where there is range anxiety, tell the car. It will use its computer and internal data connection to locate a suitable rental location that is along your route and has a car for you. It will make all appropriate reservations. Upon arrival, your electric car would transmit a signal to the rental car so that it flashes its lights to guide you and unlocks its doors for you. (The hourly car rental companies all have systems already where a transmitter unlocks the car for you.)
In many cases you would then pause, pull the rental out of its spot and put your electric in that spot. With more advanced robocar technologies, the rental would actually pull out of its spot for you. Zipcar has reserved spots for its vehicles and normally it makes no sense for the renter to have just pulled up in a car and need the spot, but it should work just fine. At Hertz or similar companies another open spot may be available.
Then off you go in your gasoline car. To make things as easy as possible, the negotiated contract should include refill of gasoline at a fair market price rather than the insane inflated price that car rental houses charge. Later come back and swap again. read more »
Numbers for buses are now worse at 4300. Source data predates the $4/gallon gas crisis, which probably temporarily improved it.
Light (capacity) rail numbers are significantly worse — reason unknown. San Jose’s Light rail shows modest improvement to 5300 but the overall average reported at 7600 is more than twice the energy of cars!
Some light rail systems (See Figure 2.3 in Chapter 2) show ridiculously high numbers. Galveston, Texas shows a light rail that takes 8 times as much energy per passenger as the average SUV. Anybody ridden it and care to explain why its ridership is so low?
Heavy rail numbers also worsen.
Strangely, average rail numbers stay the same. This may indicate an error in the data or a change of methodology, because while Amtrak and commuter rail are mildly better than the average, it’s not enough to reconcile the new average numbers for light and heavy rail with the rail average.
I’ve made a note that the electric trike figure is based on today’s best models. Average electric scooters are still very, very good but only half as good as this.
I’ve added a figure I found for the East Japan railway system. As expected, this number is very good, twice as good as cars, but suggests an upper bound, as the Japanese are among the best at trains.
I removed the oil-fueled-agriculture number for cyclists, as that caused more confusion than it was worth.
There is no trolley bus number this year, so I have put a note on the old one.
It’s not on the chart, but I am looking into high speed rail. Germany’s ICE reports a number around 1200 BTU/PM. The California HSR project claims they are going to do as well as the German system, which I am skeptical of, since it requires a passenger load of 100M/year, when currently less than 25M fly these routes.
I have some admiration for the PETA prize for vat-grown chicken. A winner of this prize would strongly promote PETA’s ethical goals, as well as many environmental goals, for the livestock industry is hugely consumptive of land, as it takes far more grain to feed animals than it takes to feed us, per calorie.
One part I admire, in a sardonic way, is the way it will make some people’s heads explode. The environmental destruction of livestock, and the cruelty, are well established. However many of the people who believe that most fervently also are very suspicious of synthetic foods, especially at this level. They would never say it, but they sometimes take actions which amount to choosing the starvation of people over the introduction of GMOs in the food supply. Not that the latter does not have its risks and unanswered questions, but that the costs are so high. PETA’s vat-grown chicken will cause massive debate when it comes.
But the contest is too hard (and has a 2010 deadline that seems designed to be impossible.) It requires a meat that people can’t tell from chicken that matches the market price of chicken and can sell. Oddly, it doesn’t require that the process be more efficient than chicken factory farms in terms of energy or land, though the cost pushes that way. But reproducing the texture and structure of chicken is a hard problem. Current work on vat-grown meat suggests less textured versions (for use in sausage and ground meat forms) will come first.
So I would propose a lesser prize, the production of vat-grown egg white, egg yolk and/or milk. As liquids, the task is probably an easier one. And these products have so many uses in foods, even if you can’t make something that fries up like an egg.
Of course vegetarians (as opposed to vegans) eat eggs and diary, though the PETA variety of vegetarian will insist these products come from humane farms, with free range animals, no hormones and no forced production. The agribusiness dairy and egg farms are not this way, they will point out — and they also consume a lot of land and generate lots of methane. And others will point out that overuse of eggs and dairy has health issues. But it’s a real prize.
The other way I would make their prize more winnable (if that’s their goal) would be to remove the requirement of of being indistinguishable. Instead, I would make the creation of a superior product qualify for victory. Instead of having an independent panel say “I can’t believe it’s not chicken,” I think it would be sufficient to have them say, “This is not chicken, but I like it as much or better than chicken as a meat.” And to prove this the market, where people are buying it instead of the equivalent bird. It’s true that an exact duplicate would have a faster adoption curve, but the wholly new food would get there eventually if people found it tasty. Tofu is tasty but chicken eaters don’t say they prefer it to chicken.
With eggs and dairy I think a perfect reproduction is more possible, in that you “just” have to duplicate the mammary tissue that produces the milk, for example. And this must be living, which may be a lot harder than the vat grown meat which may never fully be classed as living tissue. But my intuition says it will be easier, and fairly dramatic in effect.
I’m impressed with a great interactive map of the U.S. power grid produced by NPR. It lets you see the location of existing and proposed grid lines, and all power plants, plus the distribution of power generation in each state.
On this chart you can see which states use coal most heavily — West Virginia at 98%, Utah, Wyoming, North Dakota, Indiana at 95% and New Mexico at 85%. You can see that California uses very little coal but 47% natural gas, that the NW uses mostly Hydro from places like Grand Coulee and much more. I recommend clicking on the link.
They also have charts of where solar and other renewable plants are (almost nowhere) and the solar radiation values.
Seeing it all together makes something clear that I wrote about earlier. If you want to put up solar panels, the best thing to do is to put them somewhere with good sun and lots of coal burning power plants. That’s places like New Mexico and Utah. Putting up a solar panel in California will give it pretty good sunlight — but will only offset natural gas. A solar panel in the midwest will offset coal but won’t get as much sun. In the Northeast it gets even less sun and offsets less coal.
Much better than putting up solar panels anywhere, howevever, is actually using the money to encourage real conservation in the coal-heavy areas like West Virginia, Wyoming, North Dakota or Indiana.
While, as I have written, solar panels are a terrible means of greening the power grid from a cost standpoint, people still want to put them up. If that’s going to happen, what would be great would be a way for those with money and a desire to green the grid to make that money work in the places it will do the best. This is a difficult challenge. People sadly are more interested in feeling they are doing the right thing rather than actually doing it, and they feel good when they see solar panels on their roof, and see their meter going backwards. It makes up for the pain of the giant cheque they wrote, without actually ever recovering the money. Writing that cheque so somebody else’s meter can go backwards (even if you get the savings) just isn’t satisfying to people.
It would make even more sense to put solar-thermal plants (at least at today’s prices,) wind or geothermal in these coal-heavy areas.
It might be interesting to propose a system where rich greens can pay to put solar panels on the roofs of houses where it will do the most good. The homeowner would still pay for power, but at a lower price than they paid before. This money would mostly go to the person who financed the solar panels. The system would include an internet-connected control computer, so the person doing the financing could still watch the meter go backwards, at least virtually, and track power generated and income earned. The only problem is, the return would be sucky, so it’s hard to make this satisfying. To help, the display would also show tons of coal that were not burned, and compare it to what would have happened if they had put the panels on their own roof.
Of course, another counter to this is that California and a few other places have very high tiered electrical rates which may not exist in the coal states. Because of that — essentially a financial incentive set up by the regulators to encourage power conservation — it may be much more cost-effective to have the panels in low-coal California than in high-coal areas, even if it’s not the greenest thing.
An even better plan would be to find a way for “rich greens” (people willing to spend some money to encourage clean power) to finance conservation in coal-heavy areas. To do this, the cooperation of the power companies would be required. For example, one of the best ways to do this would be to replace old fridges with new ones. (Replacing fridges costs $100 per MWH removed from the grid compared to $250 for solar panels.)
The rich green would provide money to help buy the new fridge.
An inspector comes to see the old fridge and confirms it is really in use as the main fridge. Old receipts may be demanded though these may be rare. A device is connected to assure it is not unplugged, other than in a local power failure.
A few months later — to also assure the old fridge was really the one in use — the new fridge would be delivered by a truck that hauls the old one away. Inspectors confirm things and the buyer gets a rebate on their new fridge thanks to the rich green.
The new, energy-efficient fridge has built in power monitoring and wireless internet. It reports power usage to the power company.
The new fridge owner pays the power company 80% of what they used to pay for power for the old fridge. Ie. they pay more than their actual new power usage.
The excess money goes to the rich green who funded the rebate on the fridge, until the rebate plus a decent rate of return is paid back.
To the person with the old fridge, they get a nice new fridge at a discount price — possibly even close to free. Their power bill on the fridge goes down 20%. The rest of the savings (about 30% of the power, typically) goes to the power company and then to the person who financed the rebate.
A number of the steps above are there to minimize fraud. For example, you don’t want people deliberately digging out an ancient fridge and putting it in place to get a false rebate. You also don’t want them taking the old fridge and moving it into the garage as a spare, which would actually make things worse. The latter is easy to assure by having the delivery company haul away the old one. The former is a bit tricky. The above plan at least demands that the old fridge be in place in their kitchen for a couple of months, and there be no obvious signs that it was just put in place. The metering plan demands wireless internet in the home, and the ability to configure the appliance to use it. That’s getting easier to demand, even of poor people with old fridges. Unless the program is wildly popular, this requirement would not be hard to meet.
Instead of wireless internet, the fridge could also just communicate the usage figures to a device the meter-reader carries when she visits the home to read the regular meter. Usage figures for the old fridge would be based on numbers for the model, not the individual unit.
It’s a bit harder to apply this to light bulbs, which are the biggest conservation win. Yes, you could send out crews to replace incandescent bulbs with CFLs, but it is not cost effective to meter them and know how much power they actually saved. For CFLs, the program would have to be simpler with no money going back to the person funding the rebates.
All of this depends on a program which is popular enough to make the power monitoring chips and systems in enough quantity that they don’t add much to the cost of the fridge at all.
But this is a consequence of many factors, and surprisingly, shared transportation is not an inherent winner. Let’s consider why.
We have tended to build our transit on large, heavy vehicles. This is necessary to have large capacities at rush hour, and to use fewer drivers. But a transit system must serve the public at all times if it is to be effectively. If you ride the transit, you need to know you can get back, and at other than rush hour, without a hugely long wait. The right answer would be to use big vehicles at rush hour and small ones in the off-peak hours, but no transit agency is willing to pay for multiple sets of vehicles. The right answer is to use half-size vehicles twice as often, but again, no agency wants to pay for this or to double the number of drivers. It’s not a cost-effective use of capital or the operating budget, they judge.
The urban vehicle of the future, as I predict it, is a small, one-person vehicle which resembles a modern electric tricycle with fiberglass shell. It will be fancier than that, with nicer seat, better suspension and other amenities, but chances are it only has to weigh very little. Quite possibly it will weigh less than the passenger — 100 to 200lbs.
Transit vehicles weigh a lot. A city bus comes in around 30,000 lbs. At its average load of 9 passengers, that’s over 3,000lbs of bus per passenger. Even full-up with 60 people (standing room) it’s 500lbs per passenger — better than a modern car with its average of 1.5 people, but still much worse than the ultralight. read more »
I was reminded yesterday, after posting more on the cost-effectiveness of energy sources, to point out an interesting new book on the economics of energy. The book is Sustainable Energy With the Hot Air by David MacKay, a physics professor from Cambridge University. What’s important about the book is that he pays hard attention to the numbers, and demonstrates that certain types of alternative energy are likely to never make sense, while others are more promising.
I only have a few faults to pick with the book, and he’s not unaware of them. He decides to express energy in the odd unit of “kilowatt-hours per day” as he feels this will make numbers more manageable to the reader. Of course with time in the numerator and denominator, it’s a bit strange to the scientist in me. (It’s the same as about 42 watts.) In a world where we often see people say “kilowatt” when they mean “kilowatt-hour” I suppose one deserves credit for using a correct, if strange unit.
My real quibble is over his decision to measure energy usage at the tank, so that an electric car’s energy usage is measured in the battery, while a gasoline car is measured in the fuel tank. Today we burn fuel to make electricity, and so electric cars actually consume 3 times the energy they put in the batteries. That’s a big factor. MacKay argues that since future energy sources (such as solar) might generate electricity without burning fuel, that this is a fair way to look at it. This is indeed possible but I think it is necessary to look at it both ways — how efficient the vehicles are today (and will be if we still generate electricity from heat) and how they might be in the future. Generating electricity from heat does complicate the math of energy in ways that people can’t agree on, so I understand his temptation.
Yesterday I was also pointed out to a solar power site called SolarBuzz. This is a pro-solar-panel site, and is rare in that it seems to do its math right. I haven’t looked at all the numbers, and I am surprised wthat with the numbers they show that they are such boosters. Their charts of payback times all focus on power costs from 20 to 50 cents/kwh. Those costs are found in Europe, and in the tiers of California, but the U.S. national average is closer to 10 cents, where there is no payback. They also use 5% for their interest rate, a low rate that is only found in strange economic times such as these — but justifiable in a chart today. read more »
As a recap, I put forward that if we are going to use our money and time to attain greener electricity, what matters is how many MWH we take off the “dirty” grid (particularly coal plant output.) I measured various ways to do that, both green generation and conservation (which do the exact same thing in terms of grid offset) and worked out their cost, the MWH they take off the grid and thus the cost per MWH. Solar PV fares poorly. Converting incandescent bulbs to fluorescent in your own home or even other people’s homes fares best.
A big part of the blame lies on the fact that crystalline silicon is an expensive way to make solar cells.
It is, however, quite common since many PV plants started with technology from semiconductor fabrication.
One frequent objection is that purchasing expensive solar panels today encourages the market for solar panels, and
in particular better solar panels. Indeed, panel makers are generally selling all they can make. Many hope that this demand will encourage financing for the companies who will deliver panels at prices that make sense and compete with other green energy.
I call this being “evangelical green.” Leading by example, and through encouraging markets. While I understand the logic, I am not sure I accept the argument. read more »
Last week I wrote about what I consider the main goal of green electricity
efforts, namely to stop burning coal. You can do that, to
some extent, by removing demand from the grid in places where the grid is
coal-heavy. Even in other places, removing demand from the grid will be
fairly effective at reducing the production of greenhouse gases.
Update: Since this article a flood of cheap solar panels from China has been changing some of the economics discussed here. I have not altered the article but some of its conclusions deserve adjustment.
No matter what you do — conserve, or put up solar or wind — your goal is
to take power off the grid. Many people however, consciously or unconsciously
take a different goal — they want to feel that they are doing the green
thing. They want their electricity to be clean. This is actually a
dangerous idea, I believe. Electrons are electrons. In terms of reducing
emissions, you get the exact same result if you put a solar panel on your
house than if you put it on your neighbour’s house. You even get a better
result if you put it on a house that’s powered by a coal plant, so long as
you also reap the benefit (in dollars) of the electricity it makes.
People don’t like to accept this, but it’s much better to put a wind
turbine somewhere windy than on your own house. Much better to put a solar
panel somewhere sunny than on your own house. And much better in all cases
if the power you offset is generated by more by coal than at your house.
However, the real consequences are much deeper. The following numbers
reveal it is generally a bad idea to put up solar panels at all, at least right
now. That’s because, as you will see below, solar panels are a terrible
way to spend money and time to make greener electricity. Absolutely
dreadful. Their only attribute is making you feel good because they
are on your roof. But you should not feel good, because you could (in theory, and I believe with not much work in practice) have
made the planet much greener by using the money you spent on the panels
in other ways.
The true goal is to find the method that provides the most bang per buck in removing load from the dirty grid.
Keep reading to see the math and a spreadsheet with some very surprising numbers about what techniques do that the best. read more »
There are many ways to go green, though as I have identified, the vast bulk of the problem is in just a few areas — personal transportation, electrical generation, building design/heating/cooling and agriculture.
While those who focus on CO2 work from the fact that both Natural Gas and Coal, which produce 70% of the USA’s electricity, emit CO2, coal is a much bigger villain.
Coal is 50% of the US electricity supply, gas is only 20%.
Coal produces all sorts of nasty pollution in addition to CO2, including sulfur products for acid rain, radioactive elements and worst of all, fine particulates, which are major killers of the elderly.
Coal mining is highly destructive, and lives are regularly lost.
Coal power plants are not as efficient as gas ones. This is both due to the simplicity of gas plants, and the fact that many coal plants are older. The worst coal plants are almost twice as inefficient, and emit more than twice the greenhouse gasses, as gas plants. Some modern coal plants are a bit better, but the gap is still large.
Coal plants are slower to turn off and on than gas plants. They are better than nuclear plants.
There are lists of more at other web sites.
The problem is that coal is cheaper. Particularly once you have the coal plant. I’ve seen estimates all over the map but many suggest that the fuel cost of coal electricity is in the range of just 2-3 cents per kwh, and 1-2 cents more for gas fired. Hydro doesn’t really have a fuel cost, and while nuclear does, it’s a much harder cost to measure.
That cheaper price has given us a 50% coal electric infrastructure. With hydro, the amount of water that is going to flow through your plant is fixed by the weather. You want to use all of it (ideally at peak times) and keep your reservoirs at the same level each year. Nuclear is hard to start and stop, so you use it for base load. It’s expensive to build, but you want to use the plants you have to their capacity.
So my understanding is that if demand on the grid goes down (say, because somebody puts solar panels on their roof or conserves energy) the first reaction of the power companies is to burn less natural gas, because it’s a bit more expensive, and the easiest thing to cut back on. However, the power grids (there are 3 main ones in the USA and various sub-grids) are not superconductors, so due to line losses, it is cheaper to reduce output on the plants closest to the reduced demand. So the situation varies a lot.
All the power sources have their downsides. Nuclear’s are well known and controversial. Hyrdo is clean but destroys river systems and habitats. Gas emits CO2 but is clean as far as fossil fuels go. (Leaks of it also emit methane.) Oil is barely used. Coal’s only upside is its price, and the existing base of coal plants and mines.
So while it is good to look at reducing all energy production that has problems, right now if you want to do something green, it’s a fair, if broad statement to say that the best way to do it is to stop the burning of coal.
What that means for people who don’t run power companies is that reducing electrical demand in a sub-grid that is heavy with coal (such as Chicago or West Virginia) is a fair bit better than doing it in a coal-light sub-grid like California. And doing it in a place like China would be even better.
There is an irony here. Californians tend, on average, to be more eco-conscious than others. This is the birthplace of the Sierra Club after all. And because it is natural for people to focus on where they live, you see lots of effort to conserve energy or use alternative energy in California. But the same efforts would get 65% more bang for the buck if they took place in the midwest or southwest. This calculator claims to report the CO2 cost of electrical production in each zip code. It uses numbers from the North American Electric Reliability Council (NERC) for different sub-grids:
NERC region acronym
NERC region name
Average emissions CO2 (lb/MWh)
Alaska Systems Coordinating Council
Electric Reliability Council of Texas
Florida Reliability Coordinating Council
Hawaiian Islands Coordinating Council
Midwest Reliability Organization
Northeast Power Coordinating Council
Reliability First Corporation
SERC Reliability Corporation
Southwest Power Pool
Western Electricity Coordinating Council
Combined National Average
This conclusion will be disturbing for some. If you’re considering putting a solar panel on your roof in California, you would do 65% better at reducing pollution if you put the panel up on a roof in Arizona. (Actually a little better as Arizona has better sun.) If you are considering putting a solar panel up in Vermont, you would do almost 3 times better to put it in the southwest, since not only is their power twice as dirty, but they get a lot more sun.
What you would not get is the personal satisfaction of seeing panels on your roof and feeling that you personally are green. But there really is no such thing as solar electrons. Electricity is just electricity. There’s a big grid (and not being grid tied is really non-green) and the most you can do is improve how green the grid is. It doesn’t make a difference if you put the solar panels up on your house or a house across town. And it makes a positive difference if you put it up where it will have the best effect. It just doesn’t feel as good.
Now, can you go put panels on another roof? Not at present. But it certainly could be made to happen. In fact, oddly, the tax breaks are better for corporations who put up panels then they are for individuals, though this may change with new laws. Leaving out rebates and credits, a business could be set up to offer people in high-sun, high-coal areas subsidized solar power on their houses. The money they would have paid their power company could go instead to pay your power company as you continue to buy energy from your cleaner grid, having reduced demand in their dirtier grid. This works best when the power prices are similar — with PG&E’s “tiered” pricing in California this may not pan out.
It would also be possible to set up green power companies that put up green power plants in coal-heavy areas. They sell their power there, and the income would flow to investors on greener grids to pay for their grid power.
However, in a future blog post you’re going to learn something even more surprising, if you’ve been a booster of solar. It’s that it is a poor idea to put up solar panels at all, even in the coal-heavy, sunny southwest. In fact, it’s one of the worst ways you could use your money to green the planet. Stay tuned.
We need renewable energy, such as solar power. Because of that, companies are working hard on making it cheaper. They can do this either by developing new, cheaper to manufacture technologies, cheaper ways of installing or by simply getting economies of scale as demand and production increase. They haven’t managed to follow Moore’s law, though some new-technology developers predict they someday will.
However, there is a disturbing paradox in these activities. Unlike computers, it does not make financial sense to buy solar (or any other low or zero operating cost energy technology) if you have reasonable confidence the price is going to improve at even modest rates.
Imagine you have an energy technology with effectively zero operating cost, like PV panels. Let’s say that it’s reached the point that it can match the price of grid power over a 20 year lifetime. That means that, if it costs $10,000, it costs $72 per month or $872 per year at a 6% cost of funds. (Since $872 buys 9688 kwh at the national average grid price of 9 cents, that means you need a 4800 watt PV system to match the grid which is hard to do for $10,000 but someday it won’t be.)
But here’s the problem? Let’s say that it’s very reasonable to predict that the cost of solar will drop by more than 9% over the coming year. That’s a modest decrease, entirely doable just with increased production, and much less than people hope from new technology. That means that your $10,000 system will cost you $9,100 to buy a year down the road. Since we are talking about a grid-equivalent price system, the cost of grid power in this example is $872. So you can buy the power from the grid, wait a year, and save money. The more you expect the price of solar to drop, the more it makes financial sense to delay. (Note that at this lower price the system is now beating the grid. What matters really is whether the dollar cost reduction of the solar system exceeds the dollar cost of the grid electricity purchased.)
Indeed, if you predict the cost-drops will continue for many years, it sadly does not make sense to buy for a long time. Effectively until your predictions show that the cost decrease of the system no longer exceeds the cost of the power generated by it. That has to eventually come some time, since as it gets very cheap it can’t really drop in price by more than the cost of grid power, especially while there are physical install costs to include in the mix. But it can certainly drop by 6% per year for a decade, which would take it down to half its original cost. Possibly longer.)
Now, you will note I speak of the financial cost. This ignores any motivations based on trying to be greener. This is the analysis that would be done by somebody who is simply looking for the best price on power. This is frankly how most people think. This can be altered by both government incentives to buy solar and by externality taxes on polluting grid power.
This also applies not simply to solar, but any technology where you invest a lot of money up front, and have close to zero operating cost. Thus wind, geothermal and certain other technologies face the same math. Even nuclear to some extent.
All of this also depends in your confidence in your predictions. The more uncertain your predictions of price drops, the more you might be pushed in other directions to obtain certainty.
The paradox is this. We may be in a situation where solar is competing with grid power, and many are poised to buy it. If many do buy it, economies of scale will drive the price down. Thus, nobody should buy it, as they should wait for that price decrease! But if nobody buys it, it won’t decrease in price as much, creating a chaotic system. Some will buy it (to be green, for example) so it’s not a total loss, but it becomes harder to understand.
We’re used to dealing with computers, which reduce in price not just 6% a year but 40 to 50%. We’ve all felt the dilemma over whether to buy a computer or other electronic device that will lose its value so quickly, or whether to wait. However in that case, if we wait, we don’t get our nice new computer or camera, and thus lose out. You can wait forever which makes no sense. This is not the same logic with power. With power, we’re talking about a commodity that you can buy elsewhere, and get all the benefit — for less than the depreciation on what you considered buying.
What can keep the market for solar going if it looks like it will drop in price? Well, first of all, many people want to buy solar other than to save money. (Indeed, only a few people today with high local electricity prices and fat government rebates can save money with it.) Secondly, it seems that few people, even if their goal is to save money, think this way. And if they do, they are uncertain of their predictions, and would rather get the solar now than risk grid power going up or solar going down. But curiously, it remains the case that if people make predictions of cheap solar in the near term, and they are believed, it should kill most sales of solar in the present term.