Wednesday, February 13, 2013

Hybrid Energy Production via Compressed Air

Using compressed air as a means of storing surplus grid energy is one of the many proposed means of increasing our energy grid's overall sustainability.  By reducing the variability of energy produced from renewable sources and allowing output to match demand we would be able to offset a good deal of our current coal based energy production.  One of the many challenges of using compressed air as a means of energy storage is reheating the air back to a viable temperature when you want to produce power. What I would propose is the development of a class of power plant that is intended to be reasonably environmentally friendly, but acknowledges that use of additional technologies would provide the necessary short term risk reductions that current utilities embrace.
None of the technology components I will suggest are untested or high in maintenance costs (as I understand things, not saying much but I thought full disclosure and all that)
Solar thermal plants are an established platform for producing cost effective renewable energy to the grid.
Natural gas has been suggested as a means of augmenting solar thermal plants to allow them to operate at night.
Firms like LightSail Energy (actually they may be the only company exclusively doing this tech) have made tremendous strides towards making the compression phase of compressed air energy storage more energy efficient.

By combining these various technologies into a singular facility you could produce an extremely efficient hybrid facility capable of producing grid levels of power 24/7 in tandem with storing surplus energy from the grid until demand arrives.

In the image above you can see how the system configuration might be roughly laid out.  As the grid produces more energy than customers demand through out the day, large compressors would operate to store air in tanks place throughout the facility (as solar thermal plants already have to disrupt their region of operation you might as well take full advantage of that and keep the tanks close to home)  During day time operations the solar thermal power plant would operate almost exactly as traditional solar thermal facilities excluding one key feature, the cooling system, the waste heat of the plant would first be piped through a heat ex-changer connected with the compressed air generator.  Providing a wonderful operational synergy between the two operations, the compressed air gaining the necessary thermal energy to output as much power as possible, while the solar thermal plants operating fluid receives more robust cooling than ambient air temperatures would allow for (also providing an efficiency boost).
Earlier I alluded to the use of natural gas in this configuration which might seem confusing if this system is so "cool" on paper.  This is a feature that hopefully might not be necessary, but being realistic is rarely a terrible idea.  There are proposals on the books (there may also be facilities in operation) to have solar thermal  power plants that have natural gas burners near the heat collectors to allow for night time operations.  This theoretical power plant could most assuredly take advantage of this design characteristic as well to help ensure utilities found the design as useful as possible.
All in all what I'm putting down is a relatively straight forward design suggestion, as it turns out most of the elements were already suggested by others before I wrote this entry (I just didn't find out until I started putting words to webpage)

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