You can save a lot of energy and CO2 by creating your own solar hot water heater to keep heat up your homes hot water using the free energy from the sun.  Build a wooden box to hold the copper pipe.  Inside the box connect together copper pipes into an S shape.  On top of that are aluminum plates that will be sprayed black to absorb the suns heat.  This heat will go from the aluminum into the pipes which will raise the temperature of the water to probably around 40 degrees.  He also insulates the box to keep the heat in.  Pipe comes out of the box and goes into your hot  water heater in your house. 

Heating water in your home can be one of the biggest chunks of your power bill.  By heating your water using the sun you will reduce the amount of electricity used by your traditional hot water heater.