Brad Ideas - Going Green - Comments

Yup

brad — Thu, 21 Jul 2011 00:49:16 -0700

Yes, as I said, it becomes different with a super light vehicle. The solar challenge cars also deliberately have all these wide surfaces for solar, which you would not actually want for your own vehicle, but panels can still make some difference on a much lighter vehicle.

solar trailers

arbitraryaardvark — Wed, 20 Jul 2011 08:43:31 -0700

My friend tynan (tynan.com) has 1000 watts of solar on his RV. He doesn't use it as motive force, but for his power when he lives in the RV (which is usually.) A typical trailer of a tractor-trailer unit is 8 feet wide, and 48 or 54 feet long.
If the top and maybe the sides were fitted with solar panels, how many watts would that produce, and would it be a non-negligble benefit if the trailer were a deisel-electric hybrid? Let's assume the trailer isn't fully loaded at 80 tons of cargo, but is either deadheading (no cargo) or hauling a light load (no more than 20 tons.)

solar panels on a robobike

arbitraryaardvark — Wed, 20 Jul 2011 08:29:54 -0700

thinking in terms of today's electric cars is the wrong model.
the solar challenge cars go 500 miles a day on solar alone.
they are solar-only powered because those are the rules of the contest.
take that as the model, start out fully charged from the grid,
add human power (the driver and a hitchhiker, both pedaling. solves the mass transit and obesity problems.)
some form of backup power such as gas engine, compressed air, booze, fuel cell, whatever works.
your robocar ideas are a useful part of the mix.
you might not want to drive it on snow, but where i live 97+% of the time there's no snow on the roads.
a herd of solarrobobikes could hang out in the pasture,and only come back to the barn when fully charged and ready to go,
so there would always be one ready. or they could seek out grid connections on a road trip while the driver is getting coffee or showering.
the typical driver is going no more than 500 miles a day anyway. a robovehicle with a range of at least a 100 miles would be a useful gadget to have around; most trips are less than 100 miles.
a lightweight robovehicle that was solar- and human- and grid- and alternative-fuel- powered could be a viable alternative to the current imported gasoline at 25 miles/gallon $2.50-$5.00/gallon model.
I dont know what the per unit price would be if it were mass-produced in india, but it could be less than the typical detroit-built car.

You could do this

brad — Mon, 18 Jul 2011 23:13:14 -0700

But is it worth it? The only real thing it gets you is the ability to drive again quickly since the swap is faster than the recharge. But you need twice as many batteries, and some sort of swap mechanism in your house. Unless you need that fast swap, it’s a lot better to just have your panels feed the grid by day, and you charge the car from the grid by night.

There really is no solar car, at least not without deliberately doing something silly and even anti-green to make yourself believe you have a solar car. There are just two things — an electric car, and a grid. You can make the grid greener by connecting panels to it, and that is fine, but it doesn’t make you the driver of a solar car.

Safety

brad — Mon, 18 Jul 2011 23:09:37 -0700

There are a variety of solutions to this, such as adding more weight (like batteries) in any conditions where a light vehicle would not be safe. And that the light cars are not meant for high speeds, but rather urban streets, and in a world where (this is some time in the future) we’ve gone to mostly robocars so it’s all safer.

But in general, I was not under the impression that traction was much a function of total weight, because while the weight creates more friction, it also has similarly more inertia. However, I have not studied how hydroplaning varies with weight, but my understanding is that semi-trucks can hydroplane as much, if not more, than small cars due to weight distribution issues.

Actual "solar" car

Kevin — Mon, 18 Jul 2011 12:36:06 -0700

Put a bunch of panels on your house (10s of sq meters), charge batteries during the day while out. Swap the car's batteries when you get home.

Not bloody likely

Kevin — Mon, 18 Jul 2011 12:33:08 -0700

One KW/m^2 is a hard limit, being all the energy that is available from the sun. Multiply that by the panel efficiency and the angle or incidence and you get "not a whole lot" -- the best experimental panels get less than 50%, and none of them overcome trigonometry.

A practical vehicle consumes at least 10KW, so it takes you at least 2 days of charging to drive one hour, and probably 3 or 4. And this number will never improve much. Which is why this gets such justifiable derision.

Super Light Cars

Greg F — Mon, 18 Jul 2011 11:58:02 -0700

However, when we start thinking about super lightweight cars ...

At that point we have stopped thinking about the driving conditions and what is prudent safety wise. A superlight car is going to be more prone to hydroplaning not to mention problems on snow or ice covered roads.

Solar panels on robocars

Megaera — Mon, 18 Jul 2011 10:56:49 -0700

I'm getting a moderately hilarious vision of lots of selfish, self-actuating robocars in a partially-sunlit parking lot, all frantically cruising around in search of the optimally sunlit space and trying to beat out all the other robocars to it: BUMPERCARS!!! REALLY EXPENSIVE ONES!!!

Robocars on Vacation

James — Mon, 18 Jul 2011 09:03:56 -0700

I was thinking about many of your robocar ideas while vacationing in Walt Disney World this past week. To move guests they generally use standard city buses running at 20 minute intervals between the parks and resort hotels. This is fine when moving people at peak times of the day, but was wasteful during non-peak times. When we traveled mid-morning through dinner time, there was usually less than 15 people on the bus. Their quality of service demands this, but it is rather inefficient. Their hub-and-spoke system also made moving between resorts difficult. It took us up to an hour to go from our hotel to another for dinner and shopping. If there ever was a demand for a robocar implementation, this place is it. How great would it be to walk to the hotel terminal, and get in a small-ish 6-8 passenger car, and be shuttled to your desired location. At the end of the day, when thousands are leaving the parks, wouldn't it be great to just start putting guests into cars, rather then cuing them in long lines, half a mile from the park exit, waiting for the next bus?

That settles it

Mitch — Fri, 20 May 2011 01:07:28 -0700

Good on ya Brad (and everyone else) for blogging about such an important issue - let's keep the debate and emotions going! I have no idea how much carbon credits cost in Australia, but I reckon they'd be ridiculasly cheap here too since Qantas say they can off set my flight to the other side of the county for $5! Right, that settles it, I just read the whole thing & I've decided I'm buying a Prius tomorrow (second hand of course).

Awesome

rico — Fri, 29 Apr 2011 10:21:02 -0700

Just giving you kudos for the "condoms" comment when everyone starts looking hot!!!! Point taken and thank you for the laugh.

The "real" answer

brad — Sat, 23 Apr 2011 13:37:08 -0700

While it is true that reducing travel, or not building sprawl would reduce energy use. But when you talk about the “real” answer the big question is, can you get people to do it? The extent to which people will be greener for the sake of being green is not zero but it is fairly limited, especially if it costs them time, convenience or money or other things they truly value, particularly having safe environments with places for their kids to play.

The real answer has to be both greener, and desired by the public. You can pass laws but even the power of that is limited.

The real green is LESS MILES

AaronW — Fri, 22 Apr 2011 14:37:39 -0700

So air travel looks not so bad by this chart... well, that's because per-passenger it isn't so much worse than driving the whole way. But it's the distance that is the real problem. The problem with private cars isn't the inherent efficiency, it's the idea that private cars let people live in spread out sprawl and drive everywhere. If people live near transit, then they go less total miles and use less land in sprawling McMansions. It's definitely less efficient to have a bus or train go through winding subdivisions versus cars! The real answer is not to build these ridiculous subdivisions. But anyway, there are also issues of infrastructure and quality of life, because a traffic jam is a lot worse than sitting in a crowded moving train, and roads need more repair over years than rail, not to mention have more dangerous accidents and cause more stress...

Different energy cycle costs

brad — Thu, 07 Apr 2011 00:11:41 -0700

There are of course different places to measure the energy from. The most complete is well (or mine) to wheels, but that is harder to get numbers on. Fuel to wheels is what the DoE uses and that gives a ready source of numbers that have been researched and that’s why I have often used this. The coal, natural gas and even uranium took energy to get out of the ground and get to the power plant, though probably not as much as the gasoline.

All the numbers that aren’t full life cycle will mislead a bit, but the use of plug to wheels is just too far off the mark. From an energy standpoint, it’s an error of 3x, and that just can’t be accepted while an error of 20% is much more tolerable. Even from the GHG standpoint it can be an error of anywhere from on the chart from less than 1x all the way to 3x.

So has anybody added the cost of the oil wars? I believe the Iraq war cost was around $750B, spread over several years. Spread that over 15 years — though it’s hard to say just how many years of oil such a war bought — that’s about 1.5 trillion gallons of gasoline, or an extra cost in the range of 50 cents/gallon. Your mileage may vary, but that’s actually less than I would have guessed. Not that I’m saying we want to justify wars over gasoline based on the cost per gallon!