Tag Archive: Renewable energy

The first anaerobic dry fermentation biodigester in the western hemisphere is up and running at the University of Wisconsin Oshkosh. The alternative power system has been producing clean, renewable electricity from plant and food waste to supply electricity and heat for the university campus since Oct. 3.

University staff and students involved with the development of the power system had been stockpiling agricultural plant and food waste as feedstock in airless chambers and feeding it into the dry anaerobic biodigester since last summer in anticipation of bringing it online.

Anaerobic digestion is a process in which microorganisms break down biodegradable material in the absence of oxygen. As part of an integrated waste management system, anaerobic digestion reduces the emission of methane gas, CO2, and “non-methane organic compounds” or NMOCs into the atmosphere.  Anaerobic digestion is also used as a renewable energy source since the process produces a methane and carbon dioxide rich biogas suitable for energy production.

As the name indicates, ‘dry,’ as opposed to ‘wet,’ anaerobic digesters break down dry organic materials with moisture content of less than 75%, such as agricultural waste and plant material traditionally left over after harvesting a crop.

On Oct. 3, the University of Wisconsin Oshkosh team decided they had enough biogas to start-up energy production, so they turned on the plant’s gas turbine engines. The biogas from the biodigester drives the turbines, which are expected to generate enough electricity in the start-up phase to meet 5% of the university’s electricity and heating needs.

Besides producing clean, renewable energy from agricultural and food waste – corn stalks, husks, leaves, and discarded food – the bio-energy plant is serving as an ideal site for experiential learning, particularly for biology and environmental students.

Proposed plans call for revenue from the plant to flow into student scholarships, campus laboratory upgrades and expansion, and the creation of a rural community development innovation center.


The Delta company

Delta opened the world’s largest biomass power plant in the Netherlands that runs on chicken manure, in September 2008 . The plant recycles one-third of the country’s total 1.2 million tons of poultry waste produced each year, or 440,000 tons, into useable energy. Roughly 270 million kilowatt-hours of sustainable electricity can be generated to provide power for 90,000 households each year. For Dutch poultry producers sending their waste to the power plant provides an environmentally safer and less expensive way to get manure off their farms.

Environmental issues

The Netherlands are a highly productive group of countries about twice the size of New Jersey. Agriculture is one of their most important industries but in a country of 15 million people, there are 110 million livestock animals in the Netherlands at a given time, including 85 million chickens, 14 million pigs and 3 million cows. And since chickens and pigs reproduce several times a year, the total livestock turnover in the Netherlands is about 450 million per year. Not surprisingly, it’s too much manure for such a small country to process.

The animals produce about 80 to 100 million metric tons of manure per year, about two times the amount of fertilizer the soil needs to produce a good harvest of crops. Some of it gets shipped to other countries to be processed, but a lot of the manure gets ploughed into the soil anyway. Cow and pig manure are safer for the environment, but chicken manure releases CO2 and  methane, a very strong greenhouse gas. When chicken manure is used as an alternative energy source, the methane isn’t released into the environment.

Biomass as a renewable energy source

Most fuels used for electricity production,  coal, oil and natural gas, are non-renewable resources. Once they are used to produce electricity, they are gone forever. Renewable energy – wind, solar, hydropower, and biomass energy – comes directly or indirectly from solar energy. When these power sources are managed correctly, they can provide energy indefinitely.

Biomass is material from living, or recently living organisms, both plants and animals. There are five basic categories of material: wood from wood products and/or processing; high yield crops grown for energy applications; agricultural residues from harvesting or processing like manure or silage; food waste from food and drink preparation and post-consumer waste; and industrial waste from manufacturing processes.