CA Solar Power Curtialment

Huge amounts of renewable energy in California is being curtailed, that is to say, wasted because a mismatch between supply and demand. The usual solutions are mentioned: Battery storage, upgraded transmission, etc. But I wonder if a partial solution would be to pair energy inventive industries that could scale up during times of excess supply?


I suppose one can picture an automated factory that operates when there is extra energy being produced. However, that would make it hard to schedule deliveries to customers. Service industries would certainly find it difficult.

There was a report put out this summer on intermittent industry.


1 Like

This is one reason why I prefer local (home and business) solar over distant wind farms, the electrons are consumed or stored locally and excess is sent to the grid. Wind farms are one way setups.

The Captain


The simplest business might be to produce Hydrogen.

Using excess energy to split water could help make hydrogen a key player in the clean energy future - Idaho National Laboratory.

1 Like

Is that cheaper than batteries? Or reverse hydro? Those are really the only two technologies that are being widely deployed right now.

1 Like

Canada exports its excess hydropower by converting it into aluminum ingots. No reason you couldn’t do something similar with wind or solar.

BC Works (


1 Like

Some sort of storage is an obvious solution. I was thinking something more along the lines of some type of industrial productions, like say steel recycling. I’m just throwing spaghetti here, but maybe you could ramp up the energy intensive portion of the business in the afternoons in the summer and then moderate production the rest of the time. I dunno if that makes sense from a capital investment standpoint though.

1 Like

Hydro is what made me think of steel production. Nuccor has in a facility in Seattle that gets power from their own turbine on a dam on the Columbia river.


It depends. If the goal is to store the energy to supplement the grid then it is not cheaper than batteries or reverse hydro. But if the intent is to export the energy, then green hydrogen can be competitive, particular if produced from energy that would otherwise be wasted.

1 Like

Another easy way to help with this problem is to use EVs. They are essentially large batteries on wheels, and CA has the most (numerically and per capita) in the USA. All you have to do is install chargers where people spend their time during the day (work, shopping, gym, etc) and charge a substantially lower amount than people pay to charge at night in their garage. If it costs 35 cents/kWh at night in the garage, and it costs 5 or 10 cents/kWh in the parking lot at work, many people will choose to NOT charge their car at night, and instead charge it during the day at their work parking lot, or at Ralphs, or at their gym, etc.

You could try steel or aluminum factories, but that would only happen in many years, if ever, due to over the top permitting and environmental regulations that have to be overcome. This podcast that I listened to today while on the elliptical had an example of a factory (a copper smelter in Idaho) that hasn’t started up due to excessive permitting and environmental regulations. Instead a copper mine in Arizona sends their copper to China to be smelted and then ships it back to the USA for use … albeit at a higher price than it would be if smelted in the USA.


Round trip energy efficiency of reverse hydro is far better than hydrogen…about 70% vs 32%

But the problem is that for reverse hydro you have to have an ideal location that is unused already and available…and probably already has hydro installed



You are talking about using surplus power to pump water up a hill, then run the water down, through a turbine, when the power is needed? I am surprised it is that high, very surprised.

CMS Energy has had a pumped storage plant on the Lake Michigan shore for years. A few years ago, they added some windmills on the bluff. When an Alberta Clipper blows in off that lake in the winter, it will about break your ears off.


It isn’t that surprising. A motor and pump send the water uphill. And in the reverse the pump spins the motor (now a generator). ~90% efficient motors(generators) are very common. If you lose another 6% in friction in the pipes and pump you are at ~84% efficiency. 0.84 uphill and 0.84 downhill multiplies out to ~70%.
The huge amount of energy required to move the water uphill is irrelevant since it is ~mostly recaptured on the downhill side.



Which is probably why, as linked above, reverse hydro accounted for nearly 90% of utility scale electricity storage in the U.S. in 2022 - about an order of magnitude more than batteries.


I’d have to disagree. (Note that I was comparing reverse hydro to hydrogen)

Battery storage technology is typically around 80% to more than 90% efficient for newer lithium-ion devices.

Grid energy storage - Wikipedia.

Reverse hydro is probably much cheaper to build, but you have to have a location that makes it ideal.

Grid batteries can be put almost anywhere, but do have a higher cost (I assume), very little maintenance but do wear out. Reverse hydro has little maintenance, does wear out and higher capacity doesn’t factor in very much to the cost.



On the subject of round trip storage efficiencies…

From the EIA in 2021…

According to data from the U.S. Energy Information Administration (EIA), in 2019, the U.S. utility-scale battery fleet operated with an average monthly round-trip efficiency of 82%, and pumped-storage facilities operated with an average monthly round-trip efficiency of 79%.

^ ^ ^ ^ ^ ^ ^ ^

I’m not sure what you mean about hydro storage wearing out? Yes, the pumps/turbines require periodic maintenance, just like any hydro facility. But I don’t see the penstocks wearing out, for instance. Is there an upper limit to the life of a dam? With proper inspections and maintenance, I don’t know if there is an established number.

  • Pete
1 Like

A typo. I meant doesn’t wear out


1 Like

Western Energy Imbalance Market hits $4.66 billion in total benefits
Real-time energy market is poised to reach the $5 billion milestone in 2023

FOLSOM, Calif. – The Western Energy Imbalance Market (WEIM) achieved $462.05 million in cost-saving benefits in the third quarter this year, bringing total leveraged savings across California and the West to $4.66 billion since the launch of the real-time electricity market in 2014.

The increase in third-quarter economic benefits is due to a growing number of market participants and expanded resource diversity across a broader geographic footprint, allowing cleaner, less expensive energy to serve demand in place of more expensive

By the end of 2023, total WEIM economic benefits will likely reach $5 billion, hitting the real-time electricity market’s second billion-dollar milestone this year. In July, the WEIM topped $4 billion in gross cumulative benefits.

The WEIM enables participating entities to buy and sell power close to the time electricity is generated and consumed, something that was critical for helping to maintain interconnection reliability during the summer of 2023. Using state-of-the art technology, the market finds and delivers lowest-cost resources to meet immediate power needs and manages congestion on transmission lines to maintain grid reliability.

The WEIM also provides system operators real-time visibility across neighboring grids, resulting in more efficient balancing of supply and demand, particularly important on summer evenings when electricity use remains high but solar generation is rolling off
the system.

With three new entities joining in 2023, the market now includes 22 participants from 11 western states.

Because of greater regional coordination in the WEIM, the market also reduces greenhouse gas emissions by finding excess clean power at risk of curtailment and moving it across the West. Since 2014, the WEIM has reduced greenhouse gas emissions by more than 904,219 metric tons, or the equivalent of taking more than
190,000 passenger cars off the road for one year.

One of the biggest problems with pumped hydro is finding a location for the storage, since water spreads out and takes a lot of horizontal space. I’ve linked this before, but find the concept interesting (if maybe not practical, dunno.)

Pumped hydro in vertical shåft. Based on their little illustrations it’s still huge, just not huge like a lake.

They claim it can be done in any area where the geology supports it; think anyplace where mining has already been done, farmlands about to be given over to Amazon distribution centers :wink: etc. Easier to locate near population centers, and presumably pretty safe.

I wonder if it will get off the ground.

1 Like

Actually, it does, of a sort. CMS Energy recently replaced the water turbines in their Ludington pumped storage facility. On the upside, the new equipment is more efficient.


1 Like