Returning Power From Electric Cars To the Grid

First time accepted submitter icensnow writes "NRG is patenting a means of returning electric power from charged but inactive electric cars to the grid, essentially turning parked electric cars into an energy storage system for the grid. I'm having a hard time deciding if this is genius or silly."

Comments

Has potential, but...

[Smidge204]

This idea is kicked around a lot, and there are some pros and cons.

The intention is obvious: use stored energy in parked vehicles to help smooth spikes in demand and evenly distribute the load on the grid. But the difficulty is that people will want their cars to be charged when they leave work or the train station to head home, and peak demand is usually during those hours. Not only will a lot of cars be getting unplugged right when you need them, but few people will be willing to part with charge they might need to get home.
=Smidge=

Both

[hackertourist]

It's genius in that it allows load levelling without much investment by the power company, it's silly because the investment will just be moved to the user: Adding one charge cycle per day means that battery life is halved.

The only way this will take off is for users to have a financial incentive to allow the power company to do this, ie the power price during peak demand must be so high that it's cheaper to deplete your EV battery rather than draw from the grid.

Re:Both

[Spoke]

It's genius in that it allows load levelling without much investment by the power company, it's silly because the investment will just be moved to the user

Users will only allow this if they are compensated appropriately.

Adding one charge cycle per day means that battery life is halved.

Typical use case won't involve anywhere close to a full cycle. Today, typical use of an EV involves a partial cycle - probably 1/3rd to 1/2 cycle. 2 half cycles is easier on a pack than one full cycle - you can probably get 2-3x more "full" cycles by only half-cycling a modern battery pack. Limit depth of charge/discharge even more and you'll get even more use out of the pack.

That said - the real value won't come from performance large charge/discharges. It will come from many small charge/discharge events to provide grid regulation services. If a big load pops on, draw a bit of juice from batteries while conventional generators spin up. When it turns off use the excess juice to charge batteries.

Conventional generators are not good at spinning up and down quickly to match changes in load - by buffering this load and allowing the big generator to run closer to constant load you can significantly improve it's operating efficiency. Very frequently this inability to quickly match changes in load is what causes black outs (the recent San Diego blackout is a good example).

Worst case you're looking at a really hot or really cold day and you want to be able to draw 5 kW from storage during peak. This can go a long ways. I know that some utilities will pay ~$50/year just to have the option of being able to remotely control your air conditioner to keep it on a 50% duty cycle for one hour - they'll pay up to $200/year to have the option of being able to keep it off for a whole hour - and they may never need to use it!

So imagine being paid to simply leave your car plugged in to the grid just so the utility has the option of drawing power from it - and then being paid more if they actually use it. Having these resources available at little cost can be worth their weight in gold when they are needed.

As a prius driver

[Gideon Wells]

Silly as hell for now.

I can't count how many times I parked my car with my battery being "full". I mean, if surplus energy were such a huge issue then why is Toyota releasing models now you can plug in for extra "fuel efficiency". For hybrids there can't be that much of a demand. I mean, this means I would need to use more gas to charge my car more to get my good fuel efficiency, partially defeating the purpose of the car.

This seems even sillier for pure electric cars. You might as well argue that each home should have a pipeline to gas stations to siphon off their gas, in exchange for money, which you can buy back at the gas stations.

That hybrid and electric car batteries may need tapped enough to use in this system is a more worrying scenario for me. What the bleep is wrong with the local grid that we are that pinched for energy? There are fluke events that make this impractical, or it happens enough which means to me there is something wrong with the regional system that needs fixed. Not my car drained of "fuel".

Now, solar cars (maybe even cars with mini wind turbines?) I can see being part of this if you leave your vehicles outside. Once, if, your battery fills up you can sell surplus energy back as your car could be generating power during non-use unlike current electrics or hybrids.

This is not about you

[Anonymous Coward]

As a Prius driver, obviously this is not relevant to you, because you do not drive an electric car. You drive a gasoline car.

(Unless you've got one of the very latest Priuses, or you've modded your car.)

Capital Costs

[alexander_686]

So we have a expensive capital good laying around doing nothing most of the time – car batteries.

We have a variable energy source (wind or solar, take your pick) which do not necessary correlate to peak energy usage. If one were to run solely off of these 2, energy companies would have to invest in a lot of batteries, unless

Also, one could delay additional investments into the power grid by levering out the usage, where the energy Is coming from, etc. This assumes you don’t lose too much energy by taking electricity out of the battery again.