Widely available workplace charging is expensive. Every home charger is used every few days by an EV owner. Getting 1 million bidirectional chargers installed among the workplaces of 20 million employees with high usage is impossible. Some won’t have enough chargers and some will have too many (as employees change jobs), some won’t be in convenient parking spots, and it’s only useful during duck-curve seasons. There will be all sorts of grid bottlenecks getting power from high EV ownership areas to high consumption areas. Multiply everything together and you’re looking at very high cost per useful kWh delivered.

Finally, the best use of non-infinite EV cycle life is to displace gasoline combustion (1-1.5 kg/kWh), not natural gas (0.5 kg/kWh). Even if V2G use only degrades battery life by a year, it still reduces total emissions reduction potential per EV.

V2G just isn’t worth the capital expense.

Better to just use batteries made for stationary use, such as those installed at fast charging stations.

California doesn’t have a million EVs. As of 2022, there were just about 300,000.

And the peak excess available was on a Sunday, but even forgetting that, you would expect about a 4 GWh charging draw per average day, assuming about 25,000 km a year x 0.2 KWH per km x 300,000 cars ÷ 365 days.

Spread over the 6 hours of low load during the solar day, it’s just 0.7 GW of additional load assuming *all* charging was done in daytime.

No, V2x isn’t going to be the big game-changer. If California had 5 to 10 times as many EVs that mostly charged during the day, plus stationary storage, they wouldn’t have curtailment, even without V2L or V2H.

Battery storage facilities have both a power rating (MW) and an energy rating (MWh). The power rating defined the inverter capacity in the plant, which defines how much power the unit can supply to the grid or absorb from it when charging. The energy rating defines how much chemical energy the battery can store, expressed in MWh, and when combined with the power rating, the energy rating defined how long the battery can supply electricity. As examples, a unit with a power rating of 20 MW and an energy rating of 200 MWh could supply 20 MW of power for about 10 hours. A unit with a power rating of 10 MW and an energy rating of 200 MWh could supply 10 MW for about 20 hours.

I would like to see more discussion on the issue of capture cost. I think this is capturing higher pay back electricity prices when demand is high and supply of power is low. What I see is that levelized cost of electrical generation does not necessarily leads to profitablity, especially if the highest outputs are discarded because of over production. What I would like to see is some sort of profitablity measure of the electrical power produced.

Thank you for pointing this out. We were able to find the GWh ratings in EIA’s 860M data table and changes are reflected in the article.

Sadly Tesla doesn’t offer this capability now but most other manufacturers do.

Three things must happen. Widely available workplace charging, a mandate that cars have V2G, and hardware available during peak usage hours to feed power back to the grid.

As this solution does not involve big money for utility scale battery storage, the politicians bought and paid for by relevant industries will resist this, probably even in California.

I believe Finland is at the forefront for this technology.

Sincerely,
David Rubin

Energy is measured in megawatt-hours or MWh. Is that what is meant?

Power is measured in megawatts or MW, and that is what the duck curve’s vertical axis represents (though in gigawatts, which is thousands of MW). Do you mean batteries could drive 200 MW of power? If so, for how long? All night, or just part of the night?

Not trying to be pedantic. Those are very different things. I only care because the rest of the article is so well written, and I’m very interested in how effectively and economically batteries can balance intermittency of solar and wind power since the generation cost is otherwise so low.