DOD Tests Electric Cars For Back-Up Power

Might be something there if there were a surplus of unused EVs. Auto dealerships could be handy but new EVs may not be fully charged and then turn new vehicles would be slightly used. Used car lots would be better - maybe the govt would pay to charge them up.

 

Makes sense for emergency use, but my big issue with using car batteries generally for VTG is this: if arbitrage with batteries is such a great idea, why do you need the vehicle? The only rationale I can see is that the batteries will age out without having been fully used, but it still seems to me that it's wasteful in terms of energy use and the focus should be on managed charging,GTV instead.

 

I would be thrilled if I could get paid peak rates for power I am not using. And then charge during off peak.
I would also love to be able to run my house off of my EV in cases of emergency.

 

I'm not impressed ... the thermodynamics don't make sense.

Bob Wilson

 

I guess the big question is, would you want charge sucked off your car back to the grid given the high cost of EVs and the big concern over battery life and replacement costs.

EV owner ought to be compensated for this correct? They paid for the charge and lost another charge cycle doing so.

 

I'd support this in the hope that it might eventually lead to both electric and hybrid vehicles having an 110/220V AC accessory port as standard equipment.

 

Yeah, that's bothering me too.
How much energy is lost on a charge discharge cycle? (Relevant for general let's-sell-our-power-back-during-peak-times)
How much power can a car battery provide compared to, say, a generator using one gallon of gas? (Relevant for using car batteries as the emergency back up power source.)

 

What thermodynamics?

Most base vehicles travel only short distances, and there are other vehicles to go long distances on most military bases. Plug-ins make senses here in terms of fuel costs as electricity is less expensive than gasoline. But the vehicles are more expensive.

To help with the extra cost the DOD is proposing dual use of battery back up for the grid. The question is whether military bases should have battery back up. If so plug-in cars dual use makes a lot of sense.

Then finally when its not an emergency does battery buffering on micro-grids make sense. That depends a great deal on what the grid around the base looks like. I can imagine many place where this does make sense. Fort Hood is on the DoDs list, and ERCOT may be able to pay the army to buffer summer night electricity and release it during peak hours.

DoD to test using electric cars as power source | Federal Times | federaltimes.com

 

Sorry, my mechanical engineering view of the world. Every time we transform power from one to another, there is a loss and entropy increases. Taking from grid to store in battery and the later drawing the remaining fraction from the battery to feed the local grid ... just too many losses to make sense. It may make economic sense but I'm not even sure of that due to the operational scenario.

An EV vehicle is more likely to be used during the business day, when the postulated electrical rates are high. Then the get plugged in at night for cheaper charging rates, a good thing, I just don't see the return of power when the day-rates apply . . . unless the EV vehicle is not being used. Then it just becomes an expensive, mobile battery farm.

I appreciate them 'doing the experiment' even though I'm skeptical the results will be as described.

Bob Wilson

 

Imagine if you have 3 power sources
A is renewable and unpredictable variable cost is near 0
B is efficient ccgt, 50%-60% efficiency, but takes an hour to get to that effieicency
C is 30% efficient and really old. It also takes manpower to turn it on adding to costs. It has low utilization


If you can buffer A, B with a battery and release them on the grid instead of C it not only costs less money but is more efficient round trip. B, C, and D could get replaced with fast cycling ccgt, but that takes money and time.

It all depends on when that peak demand is, which makes this important. For Fort Hood, which is local to me, that is 3pm-7pm in the summer. On the base the army can easily plug in the cars after lunch, top off the charge, then leave enough for an evening trip.

The Naval Air Weapons station China Lake, CA likely won't have good synergies with peak shaving. That area needs more type B power which can take in the grid peaks. It might be helped by the back up batteries in case low rains reduce hydro power and cause black outs.

The real reason is to add solar to the base and use it for transportation instead of gasoline. The added benefit is grid stability if it works. Sceptism is good, but a $20M experiment for the military is fairly cheap if it works. Say it only has 5% chance of working, but the payoff over 20 years is $500M. It seems like a much better use of funds than having 10 instead of 5 carrier groups.

 

I agree with Bob Wilson in this. You can't fool mother nature, and the laws of physics militate against this as any kind of mass solution. It's rather like the inherent limits of wind or solar power providing a lot of our electricity needs. People who believe that need to read further into this subject.
There's also practicality. Yeah, the Prius is perfectly capable of being an emergency generator of modest proportions, but useless to us, because we need standby emergency power. It has to go on if the power fails, even if we're not there (furnace, sump pump).....and the Prius won't work for that. Our solution involved significant expense, but it turned out to be a decdicated automatic standby system (Generac 5871), which we've had for about a year and a half- and so far, so good.

 

As I said to bob, and he seems to understand a little better now, if you understand the physics no laws are being violated. You probably should look at the program, and then tell me which physical laws you think are at risk.

The program talks about dual use of plug in cars to both reduce gasoline use, and to provide battery back up to the grid. Is there a law of physics that says cars need to run on gas? That batteries can not have dual use?

Texas, where fort hood resides has quickly built a substantial amount of wind. Did physics stop these turbines from spinning? Higher percentages are waiting for grid improvements, but the plan is 20% by 2025. Lot's of college professors don't see physics violations. Have you read something that says it won't work?

Did you read that these cars are part of a microgrid that includes batteries and diesel generators.

 

H'm. This is an interesting subject, but I think there are two problems in continuing. First, I think we're talking across each other here, we're really trying to make different points. Second, I think that this subject has moved so far off-topic in a hybrid car forum that it's probably wise that I bow out. Thanks for your views.

 

I thought that you might have been making a point not having to do with these plug-ins and micro grids. It is about plug-in news, not so much about the prius.

 

These kits turn your Prius into an emergency generator