Capstone Micro-Turbines burn waste gas to make power and heat a greenhouse.

Following commissioning of these 8 Capstone Turbine Corp., biogas-fueled microturbines at a landfill in France, Capstone distributor Soffimat placed a follow-on order for more. The renewable power created feeds into the power grid of EdF, the nation's electric utility. EdF will buy the renewable energy for approximately $150,000 per year. Heat and carbon dioxide from the microturbines will be used in a nearby greenhouse. This CHP application is similar in concept to a 12-C30 landfill gas fueled CHP array near Chicago that was designated "Project of the Year" by the landfill methane division of the US EPA.The Chicago area (Antioch IL) micro-turbine project became operational in October 2003, making the high school the first in the country to use landfill gas to produce both heat and electricity. The system supplies most of the school's power. The school can buy extra electricity when it needs or sell electricity to the grid when school is closed. Savings have increased to $120,000 per year.

According to USEPA they have inventoried "more than 340 Landfill Gas Generator to Energy (LFGE) projects operating in the United States. Of those, more than 200 use LFG to generate electricity for sale to the nation's power grid. More than 100 LFGE installations generate power used directly for manufacturing and other industrial purposes. About a dozen projects, such as the BMW installation, use LFG to generate both electricity and heat, the agency says".

Small commercial enterprises, such as farms or grocery stores, can fuel micro-turbines with natural gas, on-site sourced bio-gas, or propane, set up to work as a combined heat and power (CHP) unit, where "waste" heat is used to run heating, ventilating, and air conditioning units as well as make electricity. This distributed set-up bypasses transmission loss over power lines and achieves total fuel efficiency levels far higher than that obtained by buying power commercially; plus, there is the added security of having a constant and clean backup generator, plus not having to separately fuel heating and air conditioning units. Although it's seldom mentioned, micro-turbines can be paired with solar panels, providing needed backup when the sun is less than optimal and at night.

by: John Laumer