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I'd like to take a moment to point out another really great "renewable" technology that is a clever arbitrage hack using power prices: Compressed Air Energy St

I'd like to take a moment to point out another really great "renewable" technology that is a clever arbitrage hack using power prices: Compressed Air Energy Storage. (http://en.wikipedia.org/wiki/CAES http://en.wikipedia.org/wiki/CAES) To me, this is "Grid 2.0" technology. You are moving energy from times where you have cheap excess and placing it on the grid in times of expensive need. If we are going to move to a grid with a lot of renewables, technologies like CAES and pumped hydro (https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...) are two necessary ingredients. The primary difference between CAES and pumped hydro is that CAES is cost effective for both medium (50+MW) and large (500+MW) installations, while pumped hydro is cost effective only at large scale (500MW+) installations.

virmundi 12y ago
I wish I could find the PDF from a research group on the topic of CAES. Their thesis is that we could generate most of the USA's power by installing solar in the south west. The power would get pushed to the rest of the US and stored in CAES repositories using natural caves. Each cave system should provide 3 days of sustained use for its region. This would allow for power disruptions. I can't recall if they also included natural gas as a fallback incase of protracted outage. It does open us up to a single point of attack, but I thought it was an interesting idea.
dredmorbius 12y ago
CAES works, but has some challenges, most notably the Ideal Gas law: PV = nRT That means that as you increase (or decrease) pressure, you increase (or decrease) heat. This affects CAES two ways. On storing high-pressure gas (usually air), you're creating significant heat of compression. In thin-walled structures (e.g., compressed air tanks), this is generally wasted to the environment. In subterranean storage, often in largely spent (but not fully exhausted) natural gas reservoirs (proven high-pressure gas capacity), you risk explosions within the storage reservoir as hot gas enters. On energy recovery, you've got the reverse problem: the expanding air cools rapidly. In most CAES systems, apparently, the solution is to create a combined-form recovery, in which both expanding gas _and_ natural gas combustion (to raise the gas temperature) are used, so recovery isn't fully from the compressed air storage itself. That said: it is among the more promising options, others being pumped hydro (including sea-based pumped hydro), thermal storage, and seawater-based Fischer-Tropsch fuel synthesis (low round-trip efficiency, but excellent scalability and very long-term storage). See: http://www.reddit.com/r/dredmorbius/comments/28nqoz/electrical_fuel_synthesis_from_seawater_older/ http://www.reddit.com/r/dredmorbius/comments/28nqoz/electric... http://www.reddit.com/r/RenewableTech/comments/29t6t7/seawater_pumped_hydro_storage/ http://www.reddit.com/r/RenewableTech/comments/29t6t7/seawat... (Disclaimer: I'm mod of those subs).

virmundi 12y ago

I wish I could find the PDF from a research group on the topic of CAES. Their thesis is that we could generate most of the USA's power by installing solar in the south west. The power would get pushed to the rest of the US and stored in CAES repositories using natural caves. Each cave system should provide 3 days of sustained use for its region. This would allow for power disruptions. I can't recall if they also included natural gas as a fallback incase of protracted outage. It does open us up to a single point of attack, but I thought it was an interesting idea.

dredmorbius 12y ago

CAES works, but has some challenges, most notably the Ideal Gas law: PV = nRT That means that as you increase (or decrease) pressure, you increase (or decrease) heat. This affects CAES two ways. On storing high-pressure gas (usually air), you're creating significant heat of compression. In thin-walled structures (e.g., compressed air tanks), this is generally wasted to the environment. In subterranean storage, often in largely spent (but not fully exhausted) natural gas reservoirs (proven high-pressure gas capacity), you risk explosions within the storage reservoir as hot gas enters. On energy recovery, you've got the reverse problem: the expanding air cools rapidly. In most CAES systems, apparently, the solution is to create a combined-form recovery, in which both expanding gas _and_ natural gas combustion (to raise the gas temperature) are used, so recovery isn't fully from the compressed air storage itself. That said: it is among the more promising options, others being pumped hydro (including sea-based pumped hydro), thermal storage, and seawater-based Fischer-Tropsch fuel synthesis (low round-trip efficiency, but excellent scalability and very long-term storage). See: http://www.reddit.com/r/dredmorbius/comments/28nqoz/electrical_fuel_synthesis_from_seawater_older/ http://www.reddit.com/r/dredmorbius/comments/28nqoz/electric... http://www.reddit.com/r/RenewableTech/comments/29t6t7/seawater_pumped_hydro_storage/ http://www.reddit.com/r/RenewableTech/comments/29t6t7/seawat... (Disclaimer: I'm mod of those subs).