Biogas Plant Uses Chicken Manure

WASHINGTON - Aug 27/08 - SNS -- German engineers have opened the first biogas plant in the world which runs on 70% chicken manure in Baasdorf, reports the U.S. agricultural attache for the country.

The plant was officially opened by Wimex/Gut Mennewitz GmbH, a leading German producer of broiler hatching eggs and day old chicks. Corn silage and grass silage from landscaping make up the remaining 20 and 10% of feedstock, respectively. Previously, the amount of chicken manure was believed to be limited to about 30% because of its high nitrogen content, which inhibits the microorganism activity.

The company Rueckert Naturgas has developed a new process NatUrgas (patented for Europe) that allows high percentages of manure in the feedstock mix. The feedstock is mixed and diluted with water before it is fed into a fermenter where microorganisms produce biomethane and CO2 through anaerobic fermentation. The biomethane is forwarded into a combined heat and power plant (CHP) where it is used to produce electricity and heat. Meanwhile, the fermentation residue is separated into solid and liquid fractions in a so-called "decanter". The solid fraction is dried and pressed into pellets for use as compost. The liquid fraction is further separated by means of ultra filtration and reverse osmosis into 25% highly concentrated liquid fertilizer and 75% process water. The latter is reverted into the process at step one.

The company says the economic benefits include:

- Lower volumes of food related agricultural crops needed, hence less discussions about "food versus fuel";

- Lower feedstock costs;

- Lower feedstock transports costs as the biogas plant is located near a big poultry hatchery operation.

Environkmental benefits include:

- Reduction in methane emissions compared to untreated chicken manure;

- Reduction in odor compared to untreated chicken manure;

- Elimination of dust when spreading the chicken manure on the fields;

- The fermentation process destroys germs, pathogens, and weed seeds present in the chicken manure. This potentially reduces the need for herbicide and fungicide use on fields where chicken manure is applied.

- Fermentation improves the fertilizing quality of chicken manure because it not only retains all the nutrients in the chicken manure but makes them better accessible to the plants.

The Gut Mennewitz Biogas Plant has a capacity of 2.1 MW electricity (3 units of 716 kW) and 2.23 MW heat per hour, the plant can supply the electricity needed for about 4,600 households and, in addition, replace 1.8 million liters (475,000 gallons) of heating oil. The produced electricity is fed into the public power grid while the heat is currently used to heat the chicken stables and the office buildings of the hatchery. In the future, it is expected that the heat will also be used to heat an administrative building of the city of Koethen and to dry corn for chicken feed. At full capacity the plant will use about 25,000 MT of chicken manure and 10,000 MT of corn silage and grass silage annually.

In 2007, Germany reported about 4,200 operational biogas plants. These plants predominantly run on corn silage and other plant silage materials and to a limited extent cereals and manure. About 350,000 to 400,000 hectares of farm land were used to produce the required feedstock. The German government supports biogas production through the Renewable Energy Law (EEG), which entitles biogas producers to a fixed price for electricity inserted into the public power system. The per-unit-compensation ranges between 0.124 € and 0.195 € per KWh. Power companies initially pay for the fixed prices, but ultimately the cost is borne by consumers.