by: Posted on: April 03, 2011

By Matthew Moroney

Editor’s note: This piece, like our other article Turning Pollution into Energy, focuses on the benefits of anaerobic digesters.  Of these benefits include the production of energy and the prevention of water pollution.

Matthew, the author of this piece, is currently exploring at Western Washington University, studying environmental science and chemistry.  He is dedicated to serving as a middle-man between science and the public, for the best possible societal decision-making. Ensuring everyone has the opportunity and the privilege to explore both knowledge and wilderness is a priority for him, as is ensuring the expedited adoption of renewable energy to mitigate 300 years of industrial growth. He strongly encourages dialogue, collaboration, and education and feels that environmental degradation is blocking these aspirations in many parts of our planet. Please email your comments, criticisms, and questions to greenisagoodcolor(at)gmail.com.

Struggling farms can produce electricity. Eric Leonhardt, Director of Western Washington University’s Vehicle Research Institute, advocates anaerobic digestion to assist moving past petroleum. This is a process that produces natural gas from organic matter, such as cow manure. Whatcom County’s cow manure, currently being wasted, could annually produce the equivalent amount of energy as 11 million gallons of gasoline.

Whatcom County has approximately 60,000 cows, more than any other county in Washington. These cows produce not only a large amount of milk, but also an extraordinary amount of waste. Although manure can be seen as a nuisance because of odor concerns and water quality issues, Vanderhaak Dairy sees an unavoidable opportunity and profitable resource.

Anaerobic digestion uses bacteria to convert organic matter into biogas (a mixture of approximately 40% methane and 60% carbon dioxide) that can be cleaned to burn in engines or generators for heat and power. This energy can be sold to the natural gas pipeline, or compressed and used in vehicles. Anaerobic digestion provides something unpredictable wind and solar cannot: a renewable contribution to base load electricity – the consistent power demanded by modern society.

From its anaerobic digester, Vanderhaak Dairy sells 600 kilowatts of power along with renewable energy certificates (RECs).  These RECs are sold to consumers who want to support the growth of the renewable energy industry, making otherwise economically unfeasible projects move forward profitably.  While there is a high consumer demand for RECs that accompany this source of renewable power, there is a limit in the amount of biogas that can be accepted by the grid. Excess gas must be flared; energy is wasted because of technical inefficiencies in an aging electrical grid.

The Andgar Corporation constructed and maintains Vanderhaak’s digester.  Originally a sheet metal company, Andgar then expanded into HVAC (heating, ventilating, and air conditioning) and finally entered the alternative energy market.  They have now built nine anaerobic digesters in Washington State and Oregon. Malleable markets and economic incentives encourage traditional industrial companies to incorporate alternative energy into their business plan.  This concept is fundamental to revitalizing America’s economy with green technology.

Vanderhaak Dairy’s digester is constantly pushing screened waste through a concrete chamber, digesting one million gallons every 22 days. For optimal growth of the digestive bacteria, temperature is maintained inside the digester between 37 – 39 degrees Celsius. As the slurry of digested manure is emitted from the digester, it plops into a pile where it is still warm to the touch.

The dry cellulosic material emerging from the digester is used as cow bedding and for soil conditioning, but the long fiber length of the digested material invoke possibilities of wide ranging applications such as poster board and plywood. Besides selling the electricity, Vanderhaak gains revenue in tipping fees from industries and businesses that have leftover materials from industrial food production such as chicken fats, fish waste, and breading, which are accepted and digested.  This type of waste has high energy content because it has not already been digested by an animal, making industrial preconsumer food waste especially valuable for anaerobic digesters.

Skeptics may raise concerns about  sanitation when harnessing  dairy manure for power. However, after flowing through a tank without oxygen, waste emerges more than 99% pathogen-free.  This digestate has a drastically lower chance of causing disease than raw manure, which pollutes streams and causes water quality issues. Using digested manure avoids the chance of pathogens in water and soil that is created by the use of raw manure. Power is generated while avoiding pollution.

Another detail that must be addressed is the presence of hydrogen sulfide, a naturally-occurring molecule chemically similiar to water, but with a sulfur replacing the oxygen atom.  This gas has the potential to dissolve and form an acidic solution, causing corrosion and enhanced mechanical maintenance costs. Concentrations of hydrogen sulfide in the parts per million requires catalytic removal to avoid corrosion.

Catalyst Power Incorporated in Abbotsford, B.C., operates a $5.5 M dairy digester that will soon produce 3-megawatt equivalents of natural gas directly to the utility pipeline. A cargo container with imported German technology by Planet Biogas handles the production. Multi-million dollar European equipment is landing in cargo containers across farmland, providing new business ventures for struggling dairies and farmers.

Scale is an inescapable issue for power supply. Anaerobic digesters cannot meet the entirety of America’s electricity demand. In 2010, the EPA estimated more than 8,200 farms could generate approximately 1,600 megawatts. However if all these potential watts were harvested, they would only constitute 0.00035% of America’s 2009 electrical generation capacity.

The smaller-scale base load power created by these digesters provokes the potential for distributed generation – electricity producers scattered across the countryside, with farms powering their neighbors.  This comes in sharp contrast to the centralized power plants on which our aging power grid and society currently depends. Potential electricity from animal waste is arising as a crucial component of renewable energy, the protection of water quality and connecting agriculture to innovative energy technology.

2 Responses to “WASTED POWER”

  • Nice job, Matthew! Loved the bio :)
    by: Stephanieon: Monday 4th of April 2011
  • Not only is this article discussing an interesting form of alternative energy; the writing and punctuation is strong.
    by: Anna Beeon: Sunday 24th of April 2011

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