From exploring how EVs are becoming a veritable power source, the second part of the article tackles about solar curtailment and how one could possibly generate an income from EVs.

Solar curtailment

Worry lives in California where currently 42% of utility generation uses renewables. That has already resulted, for example, on a summer afternoon, in solar curtailment because there is more solar energy available to be fed back onto the grid than the utility can absorb. There are lessons to be learned from this. Solar curtailment just recently occurred in Germany as well.

We are going to start seeing situations where there is a negative rate schedule. This means that the grid, being an old legacy system, has lots of capability to handle extra energy if there is not enough generation, i.e. an excess of load; however, too much renewable energy being fed back to the grid cannot be handled by the utilities. The solution to excess energy from renewables is to roll out vastly increased amounts of energy storage, says Worry.

California went to the federal government and stated that there is a problem when we have too much solar and we can’t use it all; we don’t have enough load in that summer afternoon to use all that excess solar energy. So maybe we should slow down Solar Income Credits. The federal government replied with a definitive No, and that they are going to maintain the credits; it is an important national initiative, so California needed to figure it out.

A government-mandated energy storage effort?

Well, California did figure it out and responded with the comment that they would roll out 1.36 GW-hrs of energy storage in their state. That is is a multi-billion dollar contract to accomplish this, but it will be distributed among many suppliers. This effort is, of course, a utility-driven, well-known market and government mandates are pushing the largest part of this effort.

Nuvation actually just announced the conformance of their utility-scale (up to 1250 VDC, scalable to a 50 battery-stack configuration for ISO container-housed electrochemical energy storage systems) battery management system to the MESA open standard for energy storage (Figure 4).

GBC-installed-in-1MW-Containerx600 Figure 4: GBC-installed-in-1MW-Container: the black box on the right side is the Nuvation Grid Battery Controller – it controls multiple battery stacks to enable megawatt-scale battery management. (Image Source: Nuvation)

Nuvation’s attainment of Draft 3 conformance streamlines the integration of their battery management system with Parker Hannifin’s MESA-conformant inverters and third-party site controllers on the Alevo GridBank project (Figure 5).

MW-at-Parker-Site-Tour-Alevo-Gridbankx600 Figure 5: Michael Worry (facing us third person from the left) at Parker Hannifin Grid Tie Division in North Carolina, showing various people from the energy storage industry the battery management systems in the new 1MW/1Wh Alevo GridBank ESS (Image source: Nuvation)

I commented that when there is a Tesla or two in everyone’s garage; that will help the energy storage effort, as well as greatly benefit Elon Musk.

Generate an income from your EV

Worry said that we can envision that in the future, EVs will no longer be a family cost but a family income source. At night, in a region where there is wind and nuclear generation running and not getting much demand from customers, you would charge up your EV and the next morning drive it from your residential area into a congested town, like an area where you work or have a business. Then discharge it for the energy needs of the local businesses at a higher rate to the EV owner than it cost you to charge it the night before. You actually generate an income from your EV. (EDN also had discussed this issue back in a 2007 blog.)

Worry has a Model S with 85 kW-hr potential, and he only needs to drive 20 miles to work, so he would happily sign an agreement to sell his energy, at a nice margin, out of his car and onto the grid. He feels that there are many others who would also see the benefit of this and do it as well.

Energy shifting of loads

I was curious how energy shifting of loads would benefit by the combined usage of batteries and ultracapacitors.

Mike Worry told us that in time-of-use billing, ultracapacitors would not necessarily a good fit. This is more of an energy play rather than a high power play because it is usually over a few hours. So for example, at Worry’s home in Campbell, CA on a summer afternoon, he can sell electricity at Rs.16.77 ($0.25) per kW-hr and then buy it back at night at Rs.2.68 ($0.04) per kW-hr---an amazing 6x spread. Go to any stock trader and tell them that we are going to give you a guaranteed market to day-trade an asset and get a 6x multiplier every single day. Too good to be true? It’s a reality.

Worry did a load shifting experiment at home by charging his EV battery from a stored energy lead-acid battery during his utility’s peak demand charge periods; the ROI was delivered in only six months. He believes this to be an artificial spread since it probably will not continue.