Monday, March 8, 2010

Cow Power

When the Blue Spruce Farm in Bridport, Vermont, turns on its lights, it's using electricity that comes from cows -- more specifically, from cow manure. And there's no foreseeable shortage -- one cow can produce 30 gallons of manure each day. So, the more than 1000 cows at Blue Spruce Farm generate a pile of power.

The farm spreads some of the manure on its fields for fertilizer. The rest they push into a 600-gallon concrete tank kept at 101 degrees Fahrenheit -- the temperature of a cow's stomach. Bacteria in the tank pick up where the cows' stomachs left off, continuing to digest the manure, producing methane that powers the farm's generators, turning out enough electricity to power 400 homes. The farm sells the extra electricity it can't use, making a tidy sum.

The total system costs were estimated at nearly $1 million and included construction of a reception pit, digester with heating and gas mixing systems, and a solids separating and drying building. Several different sources of funds contributed to the total system costs. Rural Development contributed to the electrical generator portion of the system with estimated costs of $389,275. These costs included the electrical generator, with plumbing and service hookups, and a utility building for the generator.

The process of using manure and other biodegradable substances to generate methane for fuel has gotten a lot of press.

At the University of Michigan College of Engineering, Project BLUElab is developing a prototype biodigester that uses bacterial digestions to turn animal waste, human waste, and food scraps into useful biogas (60-70 percent methane) for cooking or heating water and odorless fertilizer. Eventually, BLUElab will implement the system in the developing world.

Cleaner Cooking in Nicaragua

Cow power could also become cow production because it’s not only a major fuel worldwide but also a basic "building block" for literally dozens, or possibly hundreds, of compounds that we use to make literally thousands of products we use every day – plastics, for example.

Of course, methane has its problems, particularly in climate change. It’s as much as 60 times more potent than carbon dioxide a a greenhouse gas. In New Zealand, half of the country's greenhouse gases are methane from belching sheep and cows. (The country's government scientists want to breed livestock that don't do that.)  Another problem: As an increasing number of vehicles designed to burn hydrogen take to the road, companies will use "steam cracking" to process billions of tons of methane to make hydrogen. But no one has adequately described plans for handling the billions of tons of pure carbon that the cracking process will leave behind. Methane is also extremely dangerous to the human body -- high enough concentrations in the air can suffocate breathing creatures. And in the proper concentration (5 percent to 15 percent) in the air, methane is highly explosive.

Engineers are, or course, working on these problems, and I'm confident that they'll solve them. The questions are, how long will it take to find some answers and what alternatives should we be working on while we're waiting for solutions? (I have another question of my own: We've been talking about these problems for 40 years… why do we only get serious about solving problems when we're in crisis mode?)

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