Douglas Hvistendahl

Long Live the Cleantech Revolution

A note on Active Power: One of the reasons they are concentrating on back-ups is their cool-source design. They store compressed air over a long period of time; the quick changes are handled by flywheels, but a long outage draws on the compressed air, producing as a byproduct, cooling to take the place of the energy-using air conditioners. I'd like to see what could happen by combining their low-speed flywheels with a more efficient air storage, such as MDI's triple-expansion & heat transfer design!

Smart Grid's Enabler - Alternative Energy Storage

On Feb 09 02:35 PM Redwood_1 wrote:

>compressed
> air is in any way an efficient storage mechanism. From a mechanical
> standpoint, it's an incredibly lossy process, and one subject to

Depends on your mechanism. Isentropic compression wastes energy heating the air. Isentropic compression wastes energy cooling it. 95% isothermal is available for stationary applications. A 95% isothermal compression&expans... would be 90% efficient! The equipment is more expensive and complex, which is why almost all uses are isentropic. Maintenance needs depend on the mechanism also - the standard designs are cheap, but wear poorly. Isothermal C&E scales up very well.