Compressed Air Storage

This line says it all.

"CAES is relatively low efficiency but prices out at about $1000 per kilowatt of storage - compared to about $3000 per kilowatt for lead acid battery storage (price estimates according to EPRI)."

With (high-end) energy prices at $0.20/kWh, and commercial demand costs (high-end) at $25/kW, it looks like these lads have a long way to go if they ever want to get this very silly idea anywhere.
It would be infinitely more efficient & effective to pump water to a hill-top resevoir (during low demand periods).

Here is a reality check.
Under the conditions of power transfer agreements between BC and Alberta, BC must buy night-time surplus electricity from Alberta coal generation plants. large coal electricity plants cannot easilly adjust their output. they are most efficient when running at maximum capacity.
In return Alberta buys daytime hydro-electric generated power from BC. Hydro-electricity generation is easilly adjusted for demand... just let more or less water through the alternators.
But, because BC must keep the Columbia river full for downstream generation plants in Washington state, they cannot let less water through. So the Revelstoke dam generators simply run in no-generate mode (actually as synchronous inductors). That's 1980MW of generation plant, 100% idle all night, 365 days of the year, with the water simply spilling over the dam.

Idea :
BC has no shortage of both water & mountains. So take 100% of that electricity BC must buy from Alberta, and use it to pump water to a high mountain resevoir, storing as much potential energy as possible. Then the Revy dam could stay on-line generating it's 1980MW 24 Hrs/day. this dam is already built. And 1980MW ain't peanuts. A few PV solar panels for sure.

M

At $250/kW, that's still 10 years payback at $25/kW demand value, which is still very much high-end. Average market demand costs are half that.
The $1000/kW would need to be cut to probably $100/kW, and operating efficiency has to improve to the same level as storing potential energy via water/gravity (proven reliable technology). Big air compresors are not efficient. + When you compress air, it heats up (energy loss) and most of the H2O condenses out, so the underground cavern will fill up with water pretty quickly. I'll bet the required pumping energy would eclipse any possible energy stored.

Pumping & storing water in a few of the high-mountain hanging valleys above the Columbia River doesn't remove the water from the watershed, it remains available for release to met the commitments for US downstream generation. Transmission lines are a bottleneck, but regardless of transmission capacity, the North America grid demand simply dips at night.

I am the electrical superintendant at Panorama, a ski-area located in the upper Columbia watershed. We have a snowmaking plant with present pumping capacity of 2900 gpm (us gallons) to a head of +1600 ft, (1400gpm to +3400 Ft) with a current project to increase to 3600 gpm, and ultimate build-out of 5400. Our on-mountain pipe plant comes within 1 km of a small hanging valley suitable for a small reservoir (within our tenure). So I'm thinkin' that during the 9 months of the year when this plant sits idle, I could easily generate 1-2 MW daytime without much additional infrastructure..
We'd get the deal required from BC Hydro no problem. Likewise from the BC government. First nations would need to be stake-holders

perhaps a separate thread for additional ongoing brainstorming.

M

Air is crazy stuff

Insofar as extracting water from compressed air at the compressor, this is in practice very difficult to do, We have 3x800 = 2400 HP of air compressors, and you can't get water out of the compressed discharge air without an effective cooling tower. So far the best technology for this requires large quantities of cold water as a thermal sink, and a physically enormous air/water heat exchanger. Anything else requires significant energy input.

The condensate-traps following each compressor stage only extract a dribble of water. The water that condenses in the mountain pipes is far greater (perhaps x1000).

When the humidity is low, these 3 compressors can push 10,000 cfm at 130psig. But only if the inter-cooler flow is set perfect. Too cold and the surge-line crosses into the operating zone, requiring intake valve modulation & blow-off, ... too warm and the compressor efficiency drops radically. We want to keep the discharge air as cold as possible, since it is so much more dense than warmer air... so if it is cold then we are simply pushing more air mass... which is what we are after. When the compressors get too close to surging, blow-of valves must open, and this is a big waste of energy.

When the humidity is high, the compressor inter-coolers cannot operate efficiently, and we spend $$ pushing too much water-vapour. which is of no use to us since it simply condensees in the mountain pipes. Air-powered snowmaking is pretty pointless during high-humidity, largely because the air-compressors are so much less efficient. The produced snow quality at high RH% also sucks.

The snowmaking industry is moving away from large air-compressor based systems, because modern electric fan-gun systems bypass the compressor operation problems, and are considerably more energy efficient.

Ever wonder why a skiing lift-ticket cost $72/day?

shameless plug www.panoramaresort.com

2400 HP is pretty tiny compared to the scale that CAES would require. te operational problems would be enormous. Profitability several centuries away... if ever. By then we'll have fusion & wireless transmission. Too bad Tesla didn't have any kids.

You have my curiosity aroused

Q) At your steel-mill, did these H2O strippers rely on some form of a condenser (an after-cooler), or was it all done in the compressor's intercoolers?

I would be very interested in learning how water-stripping is done on a truly large scale air-plant.
For us this would mean significant energy efficiency gains.

We do have plans on modifying our water separator (cooling-tower) to improve it's effectiveness & overall air system efficiency. We plan on changing from an air/air cooling tower to a water/air cooling tower. (the plant sits beside a fair-sized creek). The less water vapour we push, the better. Snowmaking is only a 3-month gig (mid Oct - mid Jan), so project payback has to be quick and obvious.

The resort's overall peak demand is presently 7.8 MW, which includes 3.5 MW of snowmaking. Total annual SM consumption is about 3,100,00 kWh out of an annual total of 19,600,000 kWh
Build-out is 13 MW.

My job focus is on the resort's overall energy efficiency as I run the electric utility & keep the lifts electrics humming. We buy power from BC Hydro, resell internally, making money in the process. We presently have minimal on-site generation. A green uHydro co-generation job (1-2 MW) is on the 5-year "to-do" list.

At home my wife and I celebrate each & every kWh we harvest from our home-brew solar-thermal panels, like we are truly saving the planet . This isn't ironic... is it?

M