The Sea Cylinder Storage System

2009-05-17

I got this great idea a few months back, but never got around to writing it up; in the course of doing so, I realised that it's not entirely novel. Still, as this is going up on my all new blog, I'm going to post it anyway. It serves two functions now: firstly, it's got an image it it, which I've not done before and need to see whether it works; and, second, the image has been created with Inkscape, which I haven't used before. Okay, onto the idea.

One of the problems with many forms of renewable energy is that it comes when it comes. Wind Power is available when it's windy, solar power when it is sunny and so on. Of course, the requirement for power does not fall into the same pattern; we mostly need it during the day and the evening, when it's very cold or very hot and so on.

So, here is one of my solutions, which is the sea cylinder storage system. It looks some what like this:

Sea Cyclinder

First, you did a big hole in the ground (the cylinder), relatively close to the sea. From somewhere near the bottom you did a tunnel outward, underneath the sea to the same depth as the as the cylinder. This lets the water in. Now, you cap the top, and pump air in; this will push the water out, so that the cylinder will contain compressed air. Even with a shallow sea like the Channel, this would result in compressed air at 100m+ of pressure. When you want to store energy, you pump air in, when you want to get energy back, you let the air out again. The bigger the cylinder, the more energy you can store.

Think it's a great idea, but it's turns out not to be novel; in fact, the normal way of doing this is just to pump air into the hole in the ground. You can mine a cavern in salty areas by virtue of pumping hot water down, dissolving away a cavern. If I understand the physics correctly, you would get something like 100kJ of storage capacity per litre of compressed space, for a 10 atmosphere system; the efficiency of storage is dependent on what you do with the heat produced on compression and cold produced on expansion; I guess, in some cases you could pipe the air to where you wanted it, and use the cooling and electricity for an aircon system.

If you are interested, read all about it on wikipedia