Electric Cars that Pay

July 29, 2004 3:02 PM

Giving back to the grid... looks like the idea that AC Propulsion has of empowering owners of electric cars to send energy back into the grid (like wind and solar consumers) is getting noticed.
posted by silusGROK (14 comments total)

I'm having a hard time figuring out the benefit of this.

On the plus side you have a more robust grid because of the distributed nature of all these cars plugged into the grid

On the minus side, I'm worried about all the energy losses involved in generating electricity inefficiently from gasoline or natural gas (in the case of hybrids) or in the case of purely electric cars you're drawing off power from the grid at night and putting it back in during the day (I guess this is a plus for peak-load control).

I read about this idea in Chapter 2 (pdf) of Natural Capitalism a couple years ago. Here's an excerpt:

"Once fuel cells become cost-effective and are installed in a Hypercar,the vehicle becomes, in effect, a clean, silent power station on wheels, with a generating capacity of around 20 to 40 kilowatts. The average American car is parked about 96 percent of the time, usually in habitual places. Suppose you pay an annual lease fee of about $4,000 to $5,000 for the privilege of driving your “power plant” the other 4 percent of the time.When you are not using it, rather than plugging your car into the electric grid to recharge it—as battery cars require—you plug it in as a generating asset. While you sit at your desk, your power-plant-onwheels is sending 20-plus kilowatts of electricity back to the grid.You’re automatically credited for this production at the real-time price, which is highest in the daytime. Thus your second-largest, but previously idle, household asset is now repaying a significant fraction of its own lease fee. It wouldn’t require many people’s taking advantage of this deal to put all coal and nuclear power plants out of business, because ultimately the U.S. Hypercar fleet could have five to ten times the generating capacity of the national grid."

So here they're talking about hydrogen fuel cell-powered cars, that are effectively generating electricity from the natural gas that was used to create the hydrogen (or in my wildest fanaties, from the solar energy that was used to turn water into hydrogen via electroysis)...that's still several steps where you lose energy at each step.

But I have no math to back up my doubts, so maybe someone can provide some clarity?
posted by jacobsee at 4:05 PM on July 29, 2004

A couple of other possible advantages, though not as fleshed out as I'd like, are that these distributed "power plants" also lessen the over-all impact of power generation by also distributing environmental costs more evenly --- I liken this to feedlots: cow manure is hardly a pollutant when cows are out grazing the bucolic pastures of middle America... but it's downright lethal when washed into fetid pools on the backsides of America's feedlots.

Moreover (should this actually become the norm), these cars are a much harder target for terrorists and their ilk than centralized power production plants --- assuming we've also upgraded and idiot-proofed our distribution grid.
posted by silusGROK at 4:57 PM on July 29, 2004

Um, if you use your hybrid vehicle's power plant for electrical generation, aren't you going to consume your fuel? What's the advantage of selling the product of the fuel -- electricity, after you eat the overhead of generation -- back to the grid over, say, selling your excess fuel? Or saving it for later?

I can't figure out what the benefit to users of widespread vehicle generation is supposed to be.

This sounds to me like a scam for utility monopolies to get electricity below generation cost that they can then charge customers exhorbitant fees to distribute. Golly, thanks PG&E!
posted by majick at 4:59 PM on July 29, 2004

I guess anything that moves towards decentralizing the power grid would probably be a good thing for various reasons. But these kinds of things aren't going to happen unless there is some kind of short-term incentive to get over the inertia of continuing with our current model. I just don't have a real good feel if these kinds of things are practical (yet).

On preview: I don't see it as a scam...people will hardly be fooled into doing something this complicated unless there's a real incentive to do so. Rather, I feel it's a good idea on paper with some tricky facts to overcome yet...
posted by jacobsee at 5:03 PM on July 29, 2004

One of the main assumptions would have to be that peak power would be worth more than off-peak power. The idea that you could charge up your battery at home during the cheaper night hours, and then sell it back for a profit during the expensive daylight hours...all the cars are acting as a big distributed battery that helps the power company to even out the load on their plants, so they only have to build as much capacity as the average load, rather than the peak load.
posted by jacobsee at 5:06 PM on July 29, 2004

This is a great idea ONCE fuel cells are viable. Until then, its a lose/lose situation as jacobsee mentions above, using a gas engine to produce power is convenient in a rolling mechanism but its not effecient as a real means of generating power.

Wind and solar draw on resources that don't create a negative sum power arrangement and shouldn't really be considered in the same frame of thought as an electric car, until we reach that critical point where fuel cells are viable.
posted by fenriq at 6:27 PM on July 29, 2004

I think the reason a lot of people are having trouble understanding why anyone would want to do this is that in most of the country, energy is cheaper from the wall socket then the gas station. Which makes this idea simply seem insane. On the other hand, places with seriously messed up power grids (such as california) this idea makes perfict sense.
posted by delmoi at 8:31 PM on July 29, 2004

More specifically, a gallon of gasoline has 35.16 kilowatt hours of energy. At $2 a gallon, that works out to 5.6 cents per KWh.


Actually that's pretty cheap. In comparison, during the height of the California energy crisis, power cost around $3.90 for a KWh. If anyone had been able to hook their cars to the grid and sell at market prices, they would have made a fortune. They would have made $136 a gallon, two thousand dollars a tank!. Buth prices were so high because of Enron's illegal manipulation.


Currently, the price in cali is about 10c a KWh, meaning you'd make about $1.75 profit per gallon, or about $20 a tank (this is profit). And that's not counting the inefficiencies of car engines.
posted by delmoi at 8:46 PM on July 29, 2004

Unfortunately, the efficiency of a gasoline engine is pretty low—typically 25–30%—which would make converting gasoline at $2/gallon to electricity a losing proposition unless electricity costs exceed $0.20/kWh, discounting wear on your car's engine. Fuel cells won't really help the matter, either. Their efficiencies are no better, they rely on more expensive fuels, and they have severe lifespan issues. Large power plants can be up to 60% efficient and utilize cheaper fuels. It takes some pretty whacky circumstances to make hooking your car up to the grid profitable.
posted by yarmond at 11:35 PM on July 29, 2004

yarmond: I think autombile engines are about 60% efficent, but more energy is lost between the driveshaft and the pavement.
posted by delmoi at 11:45 PM on July 29, 2004

also gas engines are most efficent at a certan speed, which they are not always at when driving.
posted by delmoi at 11:46 PM on July 29, 2004

This sounds to me like a scam for utility monopolies to get electricity below generation cost that they can then charge customers exhorbitant fees to distribute. Golly, thanks PG&E!

No, because they can only charge you if you actually use their network. Distributed generation avoids the transmission network so there are no Transmission Use of System charges. There will be distribution charges for any electricity but the potential for profit for utility companies will be reduced and this should reflect in the price paid for electricity plus for the competitiveness of those generating and selling at the distributed level. In fact besides getting the technology working the main problem with a move to this form of distributed generation is that the current regulation makes it difficult for network owners to properly manage and develop their networks and maintain security and quality of supply whilst also making a profit under the new paradigm that would be required. Whilst the micro level of generation as discussed in the FPP links is a more extreme variant of the problem, as greater levels of renewables and CHP are attached to the gird, or wish to attach to the grid, then different approaches to network management are likely to be required.
Currently, most electricity networks are passive, that is, generators are connected to the grid and then produce electricity which moves 'downstream' to the consumer. Increasing levels of distributed generation is likely to require a switch to 'active management' of networks, wherein greater control of the network can react more responsively to shifts in supply and demand of electricity, and where electricity is flowing in both directions within the network. This will require the increased application of information and communication technology as discussed here (pdf, 1.5M). However, the development of active networks is militated against by most existing regulatory systems as these systems tend to favour the old model of centralised generation and tend not to encourage any innovation on the part of network operators by failing to reward the increased risk it entails with any opportunity for increased returns.
Denmark, with its high percentage of wind generation has been leading the way in applying active network management techniques, though the Bonneville Power Administration in California has apparently also been doing some work in the area.

With regard to California, IIRC, it was calculated that there were sufficient generators of one kind or another already installed within the state at the time of the electricity crisis to provide up to 6% additional power, but that there was no way to provide this to the grid and meter it effectively so that it didn't happen.

delmoi: are the figures you use for electricity prices in California the current prices for wholesale electricity or what the customer pays? Distributed generators are unlikely to get the same price for the sale of their electricity as they pay to take electricity from the grid as the electricity from the grid is not just the cost of electricity generation but also transmission, distribution and supply costs plus a profit margin related to each of these.
posted by biffa at 2:58 AM on July 30, 2004

delmoi, I want your car. Mine, and most everyone else's get somewhere between 20% to 25% ignition efficiency, with only 2/3 of that actually driving the tires. Only about 15% of the gasoline's energy content gets turned into useful mechanical work. Burining gas to make electric power (as in a hybrid like the Prius) is exceptionally wasteful.

Fuels cells aren't much better. Fuel cell vehicles with hydrocarbon reformers running on natural gas (which is what the first generation fuel cell buses are) are not hugely more efficent than internal combustion vehicles.

Cars also produce about 50% of all the air polution. Running cars longer would make smog much worse. Most current fuel-cell designs, those running on natural gas or alcohols, mitigate but don't eliminate polution generation. Electric generation at a power plant, if it must be done from organic fuels, produces far less smog (less than 1% as much per unit of energy, compared with a car engine), and what smog does get produced isn't in the highest population densities.

Further, never mind that low voltage AC is enormously inefficient to transmit over anything but short distances and that step-up transformers are not cheap. DC is even worse. A car would be great to use to power your house, if parked in the drive, but not to power a house even a few hundred feet away.
posted by bonehead at 6:44 AM on July 30, 2004

Lots of good alternative/emerging tech posts on Metafilter this week.

I LIKE it!
posted by troutfishing at 9:44 AM on July 30, 2004