In the world of electric cars, some people talk about an idea called "vehicle to grid" or V2G. Renewable energy's biggest challenge is storage -- wind and solar only come at certain times of the day, but we need electricity all day. The V2G hope is to use all the batteries in electric cars as a means of grid storage.
Environmental issues, energy and electric cars
I and many others feel the best way to set urban and transportation policy is to properly price in the "externalities" into our travel, and to remove all other penalties and subsidies. If you can do this, then everybody is incentivized to improve the public good. In particular, entrepreneurs and companies are motivated this way, and it's their job to think of the new things nobody else thought of.
Today I want to look at some implications of Tesla's Master Plan Part Deux which caused some buzz this week. (There was other news of course, including the AUVSI/TRB meeting which I attended and will report on shortly, forecast dates from Volvo, BMW and others, hints from Baidu, Faraday Future and Apple, and more.)
In Musk's blog post he lays out these elements of Tesla's plan
- Integrating generation and storage (with SolarCity and the PowerWall and your car.)
- Expand into trucks and minibuses
- More autonomy in Tesla cars
- Hiring out your Tesla as a robotaxi when not using it
Except for the first one, all of these are ideas I have covered extensively here. It is good to see an automaker start work in these directions. As such while I will mostly agree with what Tesla is saying, there are a few issues to discuss.
Electric (self-driving) minibus and Trucks
In my article earlier this year on the future of transit I laid out why transit should mostly be done with smaller (van sized) vehicles, taking ad-hoc trips on dynamic paths, rather than the big-vehicle, fixed-route, fixed-schedule approach taken today. The automation is what makes this happen (especially when you add the ability of single person robocars to do first and last miles.) Making the bus electric can make it greener, though making it run full almost all the time is far more important for that.
The same is true for trucks, but both trucks and buses have huge power needs which presents problems for having them be electric. Electric's biggest problem here is the long recharge time, which puts your valuable asset out of service. For trucks, the big win of having a robotruck is that it can drive 24 hours/day, you don't want to take that away by making it electric. This means you want to look into things like battery swap, or perhaps more simply tractor swap. In that case, a truck would pull in to a charging station and disconnect from its trailer, and another tractor that just recharged would grab on and keep it going.
I've been electric car shopping, but one thing has stood out as a big concern. Many electric cars are depreciating fast, and it may get even faster. I think part of this is due to the fact that electric cars are a bit more like electronics devices than they are cars. Electric cars will see major innovation in the next few years, as well as a decline in their price/performance of their batteries. This spells doom for their value. It's akin to cell phones -- your 2 year old cell phone still functions perfectly, but you dispose of it for a new one because of the pace of innovation.
Last week, I commented on the VW scandal and asked the question we have all wondered, "what the hell were they thinking?" Elements of an answer are starting to arise, and they are very believable and teach us interesting lessons, if true. That's because things like this are rarely fully to blame on a small group of very evil people, but are more often the result of a broad situation that pushed ordinary (but unethical) people well over the ethical line. This we must understand because frankly, it can happen to almost anybody.
The ingredients, in this model are:
- A hard driving culture of expected high performance, and doing what others thought was difficult or impossible.
- Promising the company you will deliver a hotly needed product in that culture.
- Realizing too late that you can't deliver it.
- Panic, leading to cheating as the only solution in which you survive (at least for a while.)
There's no question that VW has a culture like that. Many successful companies do, some even attribute their excellence to it. Here's a quote from the 90s from VW's leader at the time, talking about his desire for a hot new car line, and what would happen if his team told him that they could not delivery it:
"Then I will tell them they are all fired and I will bring in a new team," Piech, the grandson of Ferdinand Porsche, founder of both Porsche and Volkswagen, declared forcefully. "And if they tell me they can't do it, I will fire them, too."
Now we add a few more interesting ingredients, special to this case:
- European emissions standards and tests are terrible, and allowed diesel to grow very strong in Europe, and strong for VW in particular
- VW wanted to duplicate that success in the USA, which has much stronger emissions standards and tests
The team is asked to develop an engine that can deliver power and fuel economy for the US and other markets, and do it while meeting the emissions standards. The team (or its leader) says "yes," instead of saying, "That's really, really hard."
They get to work, and as has happened many times in many companies, they keep saying they are on track. Plans are made. Tons of new car models will depend on this engine. Massive marketing and production plans are made. Billions are bet.
And then it unravels
Not too many months before ship date, it is reported, the team working on the engine -- it is not yet known precisely who -- finally comes to a realization. They can't deliver. They certainly can't deliver on time, possibly they can actually never deliver for the price budget they have been given.
Now we see the situation in which ordinary people might be pushed over the line. If they don't deliver, the company has few choices. They might be able to put in a much more expensive engine, with all the cost such a switch would entail, and price their cars much more than they hoped, delivering them late. They could cancel all the many car models which were depending on this engine, costing billions. They could release a wimpy car that won't sell very well. In either of these cases, they are all fired, and their careers in the industry are probably over.
Or they can cheat and hope they won't get caught. They can be the heroes who delivered the magic engine, and get bonuses and rewards. 95% they don't get caught, and even if they are caught, it's worse, but not in their minds a lot worse than what they are facing. So they pretend they built the magic engine, and program it to fake that on the tests.
We know electric cars are getting better and likely to get popular even when driven by humans. Tesla, at its core, is a battery technology company as much as it's a car company, and it is sometimes joked that the $85,000 Telsa with a $40,000 battery is like buying a battery with a car wrapped around it. (It's also said that it's a computer with a car wrapped around it, but that's a better description of a robocar.) (Update: Since this article was written, the cost of the Tesla battery has dropped to closer to $20,000.)
There has been lots of buzz over announcements from Tesla that they will sell a battery for home electricity storage manufactured in the "gigafactory" they are building to make electric car batteries. It is suggested that 1/3 of the capacity of the factory might go to grid storage batteries.
This is very interesting because, at present, battery grid storage is not generally economical. The problem is the cost of the batteries. While batteries can be as much as 90% efficient, they wear out the more you use and recharge them. Batteries vary a lot in how many cycles they will deliver, and this varies according to how you use the battery (ie. do you drain it all the way, or use only the middle of the range, etc.) If your battery will deliver 1,000 cycles using 60% of its range (from 20% to 80%) and costs $400/kwh, then you will get 600kwh over the lifetime of a kwh unit, or 66 cents per kwh (presuming no residual value.) That's not an economical cost for energy anywhere, except perhaps off-grid. (You also lose a cent or two from losses in the system.) If you can get down to 9 cents/kwh, plus 1 cent for losses, you get parity with the typical grid. However, this is modified by some important caveats:
- If you have a grid with very different prices during the day, you can charge your batteries at the night price and use them during the daytime peak. You might pay 7 cents at night and avoid 21 cent prices in the day, so a battery cost of 14 cents/kwh is break-even.
- You get a backup power system for times when the grid is off. How valuable that is varies on who you are. For many it's worth several hundred dollars. (But not too many as you can get a generator as backup and most people don't.)
- Because battery prices are dropping fast, a battery pack today will lose value quickly, even before it physically degrades. And yes, in spite of what you might imagine in terms of "who cares, as long as it's working," that matters.
The magic number that is not well understood about batteries is the lifetime watt-hours in the battery per dollar. Lots of analysis will tell you things about the instantaneous capacity in kwh, notably important numbers like energy density (in kwh/kg or kwh/litre) and cost (in dollars/kwh) but for grid storage, the energy density is almost entirely unimportant, the cost for single cycle capacity is much less important and the lifetime watt-hours is the one you want to know. For any battery there will be an "optimal" duty cycle which maximizes the lifetime wh. (For example, taking it down to 20% and then back up to 80% is a popular duty cycle.)
The lifetime watt hour number is:
Number of cycles before replacement * watt-hours in optimum cycle
The $/lifetime-wh is:
(Battery cost + interest on cost over lifetime - battery recycle value) / lifetime-wh
(You must also consider these numbers around the system, because in addition to a battery pack, you need chargers, inverters and grid-tie equipment, though they may last longer than a battery pack.)
I find it odd that this very important number is not widely discussed or published. One reason is that it's not as important for electric cars and consumer electronic goods.
Electric car batteries
In electric cars, it's difficult because you have to run the car to match the driver's demands. Some days the driver only goes 10 miles and barely discharges before plugging in. Other days they want to run the car all the way down to almost empty. Because of this each battery will respond differently. Taxis, especially Robotaxis, can do their driving to match an optimum cycle, and this number is important for them.
A lot of factors affect your choice of electric car battery. For a car, you want everything, and in fact must just do trade-offs.
- Cost per kwh of capacity -- this is your range, and electric car buyers care a great deal about that
- Low weight (high energy density) is essential, extra weight decreases performance and range
- Modest size is important, you don't want to fill your cargo space with batteries
- Ability to use the full capacity from time to time without damaging the battery's life much is important, or you don't really have the range you paid for and you carry its weight for nothing.
- High discharge is important for acceleration
- Fast charge is important as DC fast-charging stations arise. It must be easy to make the cells take charge and not burst.
- Ability to work in all temperatures is a must. Many batteries lose a lot of capacity in the cold.
- Safety if hit by a truck is a factor, or even safety just sitting there.
- Long lifetime, and lifetime-wh affect when you must replace the battery or junk the car
Weight is really important in the electric car because as you add weight, you reduce the efficiency and performance of the car. Double the battery and you don't double the range because you added that weight, and you also make the car slower. After a while, it becomes much less useful to add range, and the heavier your battery is, the sooner that comes.
That's why Tesla makes lithium ion battery based cars. These batteries are light, but more expensive than the heavier batteries. Today they cost around $500/kwh of capacity (all-in) but that cost is forecast to drop, perhaps to $200/kwh by 2020. That initial pack in the Tesla costs $40,000, but they will sell you a replacement for 8 years down the road for just $12,000 because, in part, they plan to pay a lot less in 8 years.
In the last few months, I have found myself asked many times about a concept for solar roadways. Folks from Idaho proposing them have gotten a lot of attention with FHWA funding, a successful crowdfunding and even an appearance at Solve for X. Their plan is hexagonal modules with strong glass, with panels and electronics underneath, LED lights, heating elements for snow country and a buried conduit for power cables, data and water runoff. In addition, they hope for inductive charging plates for electric vehicles.
An article in the LA Times suggests an idea I've seen frequently -- use electric car batteries to meet peak power demand on the grid. After all, you have a car, and it's plugged in, and it has a big battery, so instead of just charging it, have it send juice back to the grid when it most needs it.
One of the silly ideas I see often is the solar powered car. In 2011, I wrote an article about the solar powered robocar which explained some of the reasons why the idea is anti-green, and how robocars might help.
I was interested to see a concept from Ford for a solar charging station for a robocar which goes further than my idea.
One of the biggest issues with wind and solar is that they are intermittent, and so either need storage or grid-tie to work. There really is no good storage, and generally storage-based systems are highly wasteful, throwing away most of the power you generate because you want to keep the storage near full. Grid-tie is the only green choice, but it's expensive and requires expensive inverters and permits and more.
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.
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.
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.
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.
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.
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:
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:
- Theoretical perfect conversion (EPA method): 99 mpg-e(perfect)
- Heat energy formula (DoE national average): 37 mpg-e(heat)
- Cost of electricity vs. gasoline (untaxed): 75 mpg-e($)
- Pollution, notably PM2.5 particulates: Hard to calculate, could be very poor. Hydrocarbons and CO: very good.
- Greenhouse Gas emissions, g CO2 equivalent: 60 mpg-e(CO2)