While researching alternative energy investment ideas, I came across an article about a family (the Tidwell's) who, for $7500, reduced their household carbon output by 90%. They went solar and installed a corn-fed heating system.

Mike Tidwell's article from Coop America

Wow. They took advantage of state tax breaks and different programs that helped with the cost of installing the solar panels, and managed to find a gently used solar water heating system for just $1000.

Now, you might wonder about the heating system. The Tidwells are burning fuel, which releases carbon into the air, right? Yes, but the big difference is that they are burning a fuel (dry corn) that just a few months earlier was soaking up carbon from the atmosphere. So, there is no net increase in atmospheric carbon.

This is the big benefit to the planet from using renewable resources like switchgrass, corn, or soybeans as fuel. Plants store carbon while they are growing. They release it when burned. It's a fair exchange. One pound stored, one pound released.

Burning fossil fuels like oil and coal on the other hand increases the amount of carbon in the atmosphere. Before we found it and dug it up, the carbon in these fuels was stored underground where it made no contribution to atmospheric carbon -- it had been there for millions of years. The trouble came when we found it and set it free -- like Alladin and his genie or Pandora and her box.

Those fossil fuels may have provided lots of energy for humankind for a long time, but in the process, their burning changed the carbon balance by releasing billions of pounds of carbon into the atmosphere that were not there before the industrial revolution.

That is the heart of global warming - not that native people in Africa are burning their forests for fuel (although that doesn't help), but the fact that we have - and continue to - pull carbon-based fuels out of the ground, thus changing the balance.

So, the Tidwell Family, by leaving the fossil fuel world behind, are making a huge contribution. And it cost them $7500 - which breaks down to $33 a month for the life of the loan (once they factor in the energy savings).