Methane Waste as Fuel: Methane Capture Technologies for Breweries and Dairies

by Jay Sandler & Brandon Conard

One of the distinguishing characteristics of contemporary industry is the impetus to become more energy efficient while also consuming renewable sources of energy as a greater proportion of the whole. While many technologies address one or the other of these objectives, such as compact florescent light bulbs as an efficiency tool, or solar voltaic power as a renewable option, there are very few technologies which address both that are as effective as methane capture. In order to appreciate the elegance of a methane capture system, it is first necessary to remind our readers what methane is and where it comes from.

What is Methane?

Methane, ordinarily a colorless and non-toxic gas at room temperature, consists of one carbon atom bonded to 4 hydrogen atoms. It is known to be a relatively potent green house gas, and although a molecular of methane emitted into the atmosphere will dissipate in approximately 8 years, its effect on global warming is 100 times that of carbon dioxide over the same period. Methane has contributed to approximately 20% to the Earth's warming since the beginning of the industrial era.

The gas is produced both metabolically and chemically (as the by-product of industrial processes.) Metabolic methane production results from the anaerobic decomposition of organic matter on both land and sea. This metabolic route accounts for the greatest proportion of annual production with decaying matter in landfills at the top (about 24%), emissions from farm animals a close third (about 21%), and manure and waste water treatment also a significant source according to EPA measurements taken in 2003. Chemical sources include natural gas systems, mining, and steel operations.

Breweries and Dairies: Methane Waste as Fuel

The elegance of methane capture is in its capacity to turn an industrial waste product into a new source of energy. Industries primed for this kind of technology are those which use or produce a great deal of organic matter such as spent grains at breweries and manure at dairies.

So, how does it work? The organic matter is collected in an anaerobic lagoon or an enclosed tank called a digester. The material is transferred either continuously or in batches, depending on the industry (breweries tend to be batch, dairies, continuous). By controlling temperature and air flow, anaerobic bacteria will decompose the organic matter, producing methane, or biogas. The methane can be collected and siphoned to storage tanks or a generator for production of on-site energy. Not only is this source of energy renewable but it effectively up-cycles waste to energy, thereby reducing the imported energy requirements of the industrial process.

A second by-product of the conversion of waste into methane is the material drawn from the digester called sludge, or effluent. This material is rich in nutrients (ammonia, phosphorus, potassium, and more than a dozen trace elements) and is an excellent soil conditioner.

What's the pay-back? The economics of a methane capture system depend on several factors: the scale of the operation and quantity of waste products produced, operation and maintenance costs, the cost of importing gas or electricity from the local utility, and any local legal constraints that might exist. In large operations, the pay-back period can be between 4 - 6 years with significant long-term savings.

Who's using it? Methane capture is becoming an increasingly attractive option for larger-scale operations. For example, a Budweiser plant in Fairfield, California recently installed a "Bio-Energy Recovery System" which will generate more than 15 percent of the brewery's fuel needs. And New Belgium Brewing Company based in Fort Collins, Colorado has a similar plant reported to produce savings in energy needs matching those of Budweiser's plant. On the dairy side, Fiscalini Cheese Co. in Modesto, California, is also gaining notoriety for a recently installed methane conversion unit. The final capacity of the unit will be sufficient to power both the dairy barn, the 88,000 square foot cheese plant, and still have enough remaining power to roll into the community grid.

Methane capture is a viable, elegant solution to reduce external energy requirements that uses readily available renewable energy sources and is increasingly ubiquitous. If you would like more information about whether methane capture or other clean tech solutions are a good fit for your facility, contact BlueMap Inc.