i want to give you a big picture. let me take you back to 1973 and give you a sense of what our energy consumption looked like back in 1973. basically a pie of where we got our energy from. back then, more than half of our energy came from oil. almost a quarter came from coal. about 19% from gas and then if you look over there, nuclear, hyd hydro, electric from water and other were altogether less than 5% of our energy. let s take it to 2009, the latest year for which we have complete statistics. we ve gone from 52.5% dependence on oil to 37.2%. natural gas has increased to 24.2%. coal done from 22.6% to 19%. nuclear was 1.3%.
now it s 11% of what we do. hydro, exactly the same as where it was back in 1973. but we re getting 4.4% of our energy from combustible renewals and waste, which is fantastic. that other category has gone to 1.1%. within other falls geothermal. bottom line, not too many people are using geothermal. what s the issue with geothermal? you go into the ground and the temperature even ten feet under the ground is much more consistent than it is above ground. so think about it like your fridge. basically you run water through pipes that go into the ground. in winter you re taking your cooler water from your house, running it through the ground. it warms up and then comes back up and warms your house. in summer, the temperature of the water in your house is going to be hotter than it is in the ground. so you run that same water through the earth and it cools it down. it s the same way a refrigerator