Compost Energy IndexDiscussions about the value of sequestered carbon from compost in relation to global climate change tend to overlook the sometimes enormous fossil-energy inputs that go into composting. These inputs offset some apparent benefits. An essay – What’s Your Compost Energy Index? published by Will Brinton in Biocycle, examines how much equivalent fossil carbon goes into making compost carbon. Using a USDA-funded compost comparison, the article calculates energy inputs in windrow vs static compost by fuel and time records in trucking, loading, grinding, mixing, turning and aerating. The study concludes that some methods are so energy intensive that they represent a net negative carbon gain. Large turning machines are a principle concern. Fuel consumption was measured in the range of 0.05 to 0.1/GpHP (gal per horsepower hour) and depended on the make and the load. The essay is based on the extensive compost data collected by Woods End’s 1995 USDA-PA compost study examining compost maturity and N-losses in relation intensiveness of composting. Data was updated to show in 2007 terms what the energy cost per ton was based on the equipment used.  In brief: machine turning twice a week meant investing 8.4 mBTU of energy to stabilize 4.9 mBTU of carbon (an energy index -EI- of 1.72). Bucket loader turning every two-weeks gave an EI of 0.88 and a self-powered turner once every 2-weeks an EI of 0.51 — in other words, all the way from negative to positive. View the paper on Energy Index or visit the Woods End website for similar reports.