fenixnuke · HackerTrans

3 years agodiscuss

Happens frequently in CAISO midday during shoulder months (https://www.caiso.com/PriceMap/Pages/default.aspx). Renewable generation produces a lot (sunny, decent wind) and electricity usage is so low, that supply exceeds demand. Electricity has to go somewhere to keep the grid balanced, so the utilities will wholesale electricity at negative rates.

fenixnuke

5 years agodiscuss

The other thing that they can be doing is selling standby frequency response services to utilities:

https://smartgrid.ieee.org/bulletins/january-2016/energy-sto....

Sometimes utilities only need a few minutes of power to cover small gaps while ramping up/down powerplants, or if a cloud passes over a solar generation facility. Since these volumes are very small but critical, the effective price per MWH is extremely high.

When Tesla did their grid scale battery installation in Australia, this is how they made their money. Not via energy arbitrage, but with selling frequency response services. I have no idea if this is the same thing, but there are other ways to make money with energy storage as well.

fenixnuke

5 years agodiscuss

There are times where the rooftop solar and base load generation for a utility is greater than the total electricity demand. Demand and supply for the grid have to be balanced, or else you will end up tripping plants and/or damaging equipment. Since they can't "turn off" rooftop and most grid scale solar generation, and they can't really turn off and on their base load plants throughout the day, their best option is to try to sell the excess electricity on the wholesale market. The problem is that the other utilities are in the same situation, and they need to offload electricity. Since no one wants the electricity, wholesale prices will actually go negative. Basically a utility will pay another utility to turn off a base load plant and take the excess electricity from them.

This is why grid scale energy storage is such a hyped technology - if you can store that energy when supply is way too high and dispatch it when renewable generation is low (no wind/solar), you can maintain high renewable percentage in the generation mix. Without it, you can only really go up to a certain percentage of renewables.

fenixnuke

5 years agodiscuss

They are likely operating on the wholesale markets, which are market priced. For the western grid there is a significantly wider price range of prices. On peak days in the summer, prices can go up above $1,000/mwh in the late afternoon for several days. During the late fall/early spring, there are negative prices in the late morning (like $20-$50/mwh) due to extremely high solar production and low demand, so utilities are literally paying you to use electricity. It's not inconceivable to get to $1 million a year on 1 mwh of storage.

Take a look at the price maps and historical pricing data if you are curious https://www.caiso.com/todaysoutlook/Pages/prices.html

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