What do regenerative braking, electrical outlets, fuel cells, and solar cells all have in common?
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Time's up! Put your pencils down. If you answered "these are all potential sources of electrical energy for powering a automobile," you're correct.
Two of these sources of electricity are insufficient on their own. The laws of physics (in particular entropy) tell us that no matter how efficient we make a regenerative braking system, we will never be able to produce all of a vehicle's energy requirements in this way. It's not so much a source of energy as a way to reclaim some of the energy that we used to lose entirely. Today regenerative braking is primarily used in hybrid cars – cars that still have an internal combustion engine.
Likewise, I don't expect to see solar energy become the primary way we power vehicles either. "On a bright, sunny day, the sun shines approximately 1,000 watts of energy per square meter of the planet's surface." At present we don't have solar cells efficient enough to capture anywhere close to 1,000 watts per square meter per day. Not all days are sunny, not everyone wants an all-black car (solar cells could be made different colors but would be less efficient), and I'm guessing that there aren't enough square meters on a car to power a reasonably sized vehicle. Still, why not use this as a secondary source of power as well? In fact, why not have electric cars that are powered by solar, regenerative braking, plugging in to an electric outlet, AND fuel cells?
The answer is the battery. The battery is the weak link in an electric car. They are expensive in many ways: they're heavy and so increase the power required to move the vehicle, they're costly to manufacture, they have to be replaced every two or three years, and they are not particularly kind to the environment in disposal. Batteries also have trouble storing enough energy to give an electric car a range competitive with internal combustion cars.
This is a big reason why there has been so much excitement about the possibility of fuel cells. A hydrogen fuel cell automobile is electric, but there is no requirement for a battery array.
The howstuffworks.com folks describe a fuel cell as follows:
A fuel cell is an electrochemical energy conversion device that converts hydrogen and oxygen into water, producing electricity and heat in the process. It is very much like a battery that can be recharged while you are drawing power from it. Instead of recharging using electricity, however, a fuel cell uses hydrogen and oxygen.
So my question is whether a fuel cell can hold electricity produced outside the cell – from sources other than hydrogen conversion. If so, what are the limits to this storage capacity? If fuel cells can be charged with outside power (and I don't see why not), and the storage capacity is significant, I would expect to see fuel cell cars with regenerative braking, solar cells, and even the ability to "plug in" to an electrical outlet.
All of these technologies involve costs and benefits. Different auto companies will, no doubt, weigh these technologies differently. Consumers could have many options in the coming decades.
The only way a hydrogen fuel cell can "store electricity" is by using it to convert water back into hydrogen and oxygen. I don't know if any current fuel cells do that directly or not, but it could be done in a separate piece of equipment via electrolysis.
Posted by: Andrew Salamon at June 8, 2004 04:42 PMI wish it weren't so complicated, technically, politically, and socially, to make the transition to efficient fuels. I hope the research continues and that effective echnologies are welcomed by consumers in the free market.
Posted by: Kathy at June 8, 2004 09:12 PM"The battery is the weak link in an electric car"
I wonder if you are familiar with what AC Propulsion has done in their tZero ( http://www.acpropulsion.com/ ) .
350 miles per charge on battery pack composed basically of regular cellphone li-ion batteries. Of course, they basically kicked everyones asses at the Michelins Challenge Bibendum
For more of the kind, check out the links on http://www.evuk.co.uk/
IMO, fuel cells are way overrated. We could easily all drive EVs at least as commuter cars today ( see Tango at http://www.commutercars.com/ ) if Detroit would be at all interested.
Kert:
Thanks for the links, I'm going to read up and probably post on them.
It's not that Detroit has some perverse desire to see the planet destroyed or that it has sold it's soul to "evil" Oil companies.
Detroit (and carmakers everywhere) are interested in making money. If we consumers demand a particular type of vehicle, they will run to make it, but they don't want to manufacture a bunch of cars nobody will buy.
Frankly I like that both cars in my driveway are capable of cross-country travel. I don't have to have a separate expensive car for travel out-of-state.
Electric vehicles will remain a novelty until they become competitive with internal combustion vehicles. This means that they will have to meet or beat internal combustion engines in most of the follow ways:
1. Price per mile
This includes purchase price, the price of the fuel (electricity v. gasoline), and the price of maintenance.
Electricity is far cheaper per mile than gasoline.
http://auto.howstuffworks.com/electric-car.htm/printable
The purchase price is not far removed from gasoline vehicles (and would certainly be competitive if they were being mass produced at the level gasoline cars are produced).
But the maintanance price - the price of replacing the batteries every couple of years - is the kicker.
2. Range
If a car can only go 50 miles before refueling, it will not be purchased a readily as a vehicle that can travel 200 miles before refueling.
3. Speed
If it can only travel 60 mph it will be at a disadvantage also.
4. Size
If it looks like a Yugo, it won't be bought.
5. Time and opportunities to refuel
If it takes all night to recharge it's batteries and there are few opportunities to do this away from home, it will still be considered a "commuter car" even if it has a range of 200 miles.
Both hybrids and fuel cell vehicles address most of these problems better than current EVs.
Posted by: Stephen Gordon at June 9, 2004 05:08 AM"But the maintanance price - the price of replacing the batteries every couple of years - is the kicker"
li-ion batteries in conditioned packs live very long. they are reasonably cheap too, especially when mass-produced units are used, like AC Propulsion does.
"If a car can only go 50 miles before refueling"
For modern EVs, more like 300+ miles. Read the result sheet of Challenge Bibendum and browse the links.
"If it can only travel 60 mph it will be at a disadvantage also."
tZero has 100mph top speed. BTW, why does anyone need to drive faster than the legal limit ?
"If it looks like a Yugo, it won't be bought."
er .. Lexus 2054 , tZero .. Xebra roadster... what more do you need ?
"If it takes all night to recharge it's batteries"
li-ion battery packs can be almost fully recharged in about an hour. After driving 300miles straight, taking a hour long break is good safety practice anyways. Quick-swap standardized battery packs for those in hurry should not be a insurmountable infrastructure problem either.
Strange that people feel okay to recharge their cellphones overnight, but its unthinkable for cars.
"Both hybrids and fuel cell vehicles address most of these problems better than current EVs."
Not really.
http://www.challengebibendum.com/challenge/front/affich.jsp?&lang=EN
Kert, there are a number of reasons to drive faster than the legal limit, but in most places in the US, the legal limit is up around 70-75 mph on interstate highways, which is pretty fast anyways.
Lightweight electric cars have the advantage of high torque, which translates directly into acceleration, which is typically more important than top speed anyways. Lightweight is the key―every pound removed from the car costs money, since lighter materials are more expensive. Often they are also more difficult to repair. I banged a huge dent caused by another car out of the door of my Neon on my own. Just try that with fiberglass (one new door panel later...).
And electric cars are being almost or more than beat on emissions by some new PZEV (partial zero-emissions) vehicles, such as the Focus. Some PZEV vehicles are able to produce approximately the same, or fewer, emissions as an electric car (since the electric car gets most of its energy from fossil fuel power generation).
And that is a gasoline car. I've heard of Jetta TDi owners getting 45-50 mpg on diesel. Just pair with biodiesel fuels, and we have long range, low emissions, good torque, and renewable fuel. All with existing technology. No pesky batteries to charge or replace. Diesel is a hard sell in the US though, for some reason.
Posted by: Patrick O'Leary at June 9, 2004 03:13 PMKert:
"li-ion batteries in conditioned packs live very long. they are reasonably cheap too"
Each of the problems I mentioned are all being addressed by current research. Things are getting better all the time. :-)
The tZero is particularly cool. I saw a program about it recently. That car would be a kick to drive. Still, there are some trade-offs to be made.
Electric vehicles have been around in prototype form and novelty car form for a long time. The problems I've pointed out are those that have kept EVs from being competitive up till now.
"BTW, why does anyone need to drive faster than the legal limit ?"
Emergencies, fun, whatever. What people need is different from what people want and are willing to buy.
"If it takes all night to recharge it's batteries"
li-ion battery packs can be almost fully recharged in about an hour. After driving 300 miles straight, taking a hour long break is good safety practice anyways.
Agreed. But you're not always going to be refueling after a 300 mile drive. You might be on the way to work and look down and say, "Oh crap, I'm almost out of juice."
In any event an hour-long refuel compares negatively with the two minute refuel down at the local pump.
Also, the infrastructure to recharge away from home is not currently available. This is a chicken or egg problem that we've overcome before, but it typically is a long time coming.
"Quick-swap standardized battery packs for those in hurry should not be a insurmountable infrastructure problem either."
Now that is a good idea. Just pull up to the station and trade out battery packs. Of course those things weigh a ton, so I guess the trade would have to be accomplished robotically. But it could be done.
"Strange that people feel okay to recharge their cellphones overnight, but its unthinkable for cars."
Not unthinkable, just inconvenient by comparison to liquid fuel. Hybrids and fuel cell vehicles would use liquid fuel. Hybrids require no new infrastructure (except maybe smarter mechanics). Fuel cell vehicles could simply be given their own pump at existing gas stations.
Posted by: Stephen Gordon at June 9, 2004 03:33 PM"Lightweight is the key―every pound removed from the car costs money, since lighter materials are more expensive"
That is true for any vehicle, so i dont see the argument against EVs here. I'd say its actually smart not to haul around two tons, wasting energy just for getting one person to workplace. So lightweight cars are a good thing.
"(since the electric car gets most of its energy from fossil fuel power generation)"
So you think we are going to stay on fossil power generation forever ? Even now, nothing prevents me from recharing my EV from solar panels on my home roof or wind turbine in the back yard. Beat those emissions.
"In any event an hour-long refuel compares negatively with the two minute refuel down at the local pump."
Thats true. But you could always rent a generator trailer from your local gas station, if in a hurry.
"Also, the infrastructure to recharge away from home is not currently available."
Thats not the case everywhere. For example in scandinavia, parking lots in many places have power outlets to keep cars warm in cold winter. They'd have to have integrated wattmeters of course.
In sunny places, part of the infrastructure you'd need is solar cells on your cars roof so you basically get a free recharge in 8 hours while you are at work, if your parking lot is in favorable spot.
Also, note that nothing prevents EVs from using an optional low emissions diesel generator trailer for range extensions and emergencies. Its just that during like 95% of the driving you do it would not be needed.
Simply put, IMO EVs hold much more potential than all the hydrogen hype would lead you believe.
Read this recent story at sciscoop too:
http://www.sciscoop.com/story/2004/6/8/111055/3924
"Producing the hydrogen equivalent in energy to the oil now used in U.S. transport would require 10 trillion kilowatt hours of electric energy; we would have to triple our electric generation capacity."
oh, btw, theres no fundamental reason why EVs would have to drive slow.
http://www.megawattmotorworks.com/display.asp?dismode=article&artid=53
"Ohio State University’s Buckeye Bullet electric car today broke the record for the fastest speed by an electric vehicle, with a speed of 257 miles per hour at the Bonneville Salt Flats in Utah."
Ultracapacitors combined with polymer batteries show a lot of promise ...
Even electric motors have still room to grow in performance and efficiency
http://www.wavecrestlabs.com/technology/overview.html
Kert:
"Read this recent story at sciscoop too:
http://www.sciscoop.com/story/2004/6/8/111055/3924
"Producing the hydrogen equivalent in energy to the oil now used in U.S. transport would require 10 trillion kilowatt hours of electric energy; we would have to triple our electric generation capacity.""
Thanks. Did you catch my "Hydrogen, Hydrogen Everwhere" post from last February?
http://www.speculist.com/archives/000651.html
Bottom line - there is a better way to get to the hydrogen in H2O than we currently use.