CDM News - August 2007 - (Page 11)

A Better Means to Efficiency When faced with the need to decrease energy costs, a plant manager has two options: demandand supply-side management. Demand-side management refers to energy conservation and process improvements that reduce the demand for energy. Upgrades to pumping, primary sedimentation, and secondary aeration systems can signiﬁcantly reduce energy demand. However, once all avenues have been explored, the positive effects of demand-side management are limited. On the other hand, supply-side management, which refers to the handling of energy resources, such as biogas, can become a sound avenue for cost efficiency. Increasing the production of biogas and converting it into electricity, heat, or biomethane are all part of resource or supply-side management. Biogas is a resource with vast uses. For example: Heat: Biogas can be converted to heat using boilers and used for process (e.g., digester heating) and space heating. Combined Heat and Power: Especially in areas with high electricity rates, plant managers are converting biogas into electricity and heat using cogeneration equipment, such as internal combustion engines, gas turbines (conventional and mini), several types of fuel cells, and closed-cycle engines. Vehicle Fuel: Additionally, biogas can be converted into biomethane by removing the contaminants and carbon dioxide. Biomethane can be fed to natural gas pipelines or used in compressed natural gas vehicles. This is especially appealing with increases in natural gas rates and global gasoline prices. With the apparent value of biogas not just economically, but also environmentally, anaerobic digesters can be viewed as an energy source, rather than solely as a stabilization process for wastewater solids. This untapped resource can be cost-effectively enhanced to produce more biogas and achieve other performance improvements for reducing pathogens, reducing heating demand, enhancing mixing, and controlling foam, among others. Getting the most out of existing digesters is a form of asset management, one that has become a means to gain additional operational and conservation capacity. There is also an opportunity to supplement the wastewater solids fed to digesters with organic waste from food processing or other sources, such as restaurant waste. This approach—known as codigestion—has several advantages. It increases biogas production, decreases solid waste at landﬁlls, and decreases greenhouse gases by capturing and beneﬁcially using methane that otherwise could be emitted to the atmosphere at the landﬁll. And methane is 21 times more potent as a greenhouse gas than carbon dioxide. Harnessing bioenergy at wastewater treatment plants has the potential to produce enough electricity for more than 4 million people, while also reducing greenhouse gases. Diverting the organic fraction of municipal solid waste to anaerobic digesters would further reduce greenhouse gas emissions and generate enough electricity to serve more than 10 million additional people. This potential is based on wastewater treatment plants and the organic fraction of municipal solid waste in the United States alone. With worldwide application and the use of agricultural organic wastes, the potential is immense. Managing a New Resource As we look for smart, sustainable solutions to our resource challenges, we must consider economic, environmental, social, and operational objectives. David L. Parry, CDM vice president, is actively involved in several anaerobic digestion and energy projects at wastewater treatment plants and industrial facilities in the United States and Canada.

Table of Contents Feed for the Digital Edition of CDM News - August 2007

Contents Envisioning Tomorrow’s Dublin Initiative & Innovation Stabilize Mercury Mines Preserving Old Town Alexandria Taking a Hard Look at Concrete Corrosion Perspective: Harnessing Bioenergy Engineering Better Lives CDM Announces Award-Winning Projects People Highlights

CDM News - August 2007

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