Solar Cows

A friend of ours stops in from time to time unannounced, often with a technical question on his mind. Before the weather turned so cold, he asked if we had any ideas for keeping his pond open for the winter. We had nothing intriguing to offer; just a cheap way to run an electric line for heating.

Open water is a concern for farmers in winter because when ponds freeze over, cattle have one less place to get water. The practical outcomes are: more work for the farmer (finding a way to get water to the cattle), the cattle are weaker because they lack water or the cattle are concentrated in a smaller area, potentially damaging the quality of the pasture.

I’ve heard about farmers manually breaking the ice for the cattle and I’ve seen articles on windmills, which keep the water flowing, reducing the risk of freezing. Others use an electric heater, but often getting electricity to the pond is tricky and costly. After reading about solar concentrators all week, I wonder if anyone is using one to keep their pond open in the winter. It seems like the perfect tool for the job.

Although our primary goal is to produce electricity, concentrators are diverse tools. Among the uses I’ve seen so far: solar cookers, food dehydrator, water distiller, wood gasification, lighting dark rooms, hot water, in-floor heating, and heating swimming pools.

What I’ve found so far, is that not many people are building linear concentrators. I found just two examples that are similar to our plans. Ausra is an Australian company who is planning megawatt linear concentrator electrical plants. Complete with thermal storage, they expect to supply energy during low-sun, high demand (ie. nighttime) periods without difficulty. They can compete with fossil fuel generation because of the low cost of the concentrators. Close to the ground, the concentrators are easily cleaned and do not require as much structural supports against high winds as other designs.

A small scale design was built called the “aquaflector.”

This is probably the best representation of what we plan to do. The inventor is hoping to eventually use the concentrator to power PV cells. Although he has not worked out the details of electrical generation, the aquaflector does produce steam.

Although none of their designs match our plan, the philosophy of www.solarfire.org matches ours intimately. They have published open source designs for two solar concentrators. They are open to improvements and encourage others to make and sell them. Moreover, they are working on a site for collaboration on all types of solar projects. They see a larger vision than simply supplying people with solar. However, that’s their entry point. We hope to collaborate with them more closely in the future.