56 ARTICLE / MAKALE Geographic distribution of wastewater treatment plants using 16,042 wastewater treatment plants in the US Only 266 already use the 3452 use anaerobic digestion (22% of total) AGRICULTURALAND LIVESTOCK OPERATIONS With only minor modifications, microturbines can be run on waste methane from digesters at dairy, hog (pig) and poultry farm operations as easily as at wastewater treatment plants. The driver torfarm operators is to manage wastes - especially manure. in addition to providing a treatment route tor manure, with fertilizer as an end product, digestion eliminates odour problems !hat arise from storing manure in a lagoon, and prevents groundwater pollution. construction. Mostofthese existing and new projects use reciprocating engines. Over 100 microturbines are currently running on landfill gas in the US The resource is enormous, the application is technically feasible and proven, and the environmental and community benefits are huge. However, the outlook tor !his application is mixed. in the US, !here is currently a lack offinancial assistance to farm operators tor developing projects ('carrots'), and a lack of regulations mandating stricter animal waste management ('sticks'). Both ofthese are slowly starting to shift. Compared with putting microturbines at landfills orwastewater treatment plants, the costs of projects at agricultural and live stock operations are higher, tor two reasons. The waste collection system is more complicated, and farm operators are less likely to already have a collection system ora digester in place. The US currently has 35 farm-scale anaerobic digestion projects in operation, generating about 4 MW. This is a 30% increase from two years ago, and another seven projects are in start-up or under Organizations such as the New York State Energy Research and Development Authority (NYSERDA), the California Energy Commission, and the US Environmental Protection Agency's AGSTAR programme are helping by funding and facilitating new projects, and this will lead to an increase in biogas projects at farms. in general, though, we predict !hat this market will continue to consist mainly of demonstration projects rather than widespread adoption tor the next several years. Alliant Energy down on the farm The Top Deck Holstein Dairy is one of three farms so far to have benefited from Alliant Energy's drive to support distributed generation at farms in lowa and Wisconsin. Manure from 700 cows feeds a digester, which in turn producing gases that power a 100 kW reci procating engine and a 30 kW microturbine. Alliant's activities in this area are driven by two issues: O on-farm generation supports voltage levels on rural parts oftheir distribution network, potentially offsetting grid reintorcement costs O Alliant wants to support a prosperous agricultural economy in its service territories in order to maintain electricity demand, and the utility sees on-farm power generation as a contributor to this." Alliant offers to purchase gas from farmers' digesters and install, own and operate generating equipment at farms. it requires farmers to do a daily 20minute check of their equipment, with ali servicing carried out by Alliant field engineers. The company, currently running gas reciprocating engines anda Capstone microturbine, also plans to try out one of STM Power's 25 kW Stirling engines when a suitable site is identified. Alliant has a targetof20 MW ofgeneration on farms in lowa and Wisconsin. Aftergetting started in this area back in 2000, its efforts have been frustrated by the poor market conditions affecting the dairy industry. Although the company is happy to lake the capital cost of the generator and switchgear off the farmers' hands, it is more reluctant to invest in the digester. The generator and switchgear are relatively recoverable assets, whereas Alliant would prefer not to tie up capital in the immovable digester. So at present, farmers have to invest in the digester which, under present market conditions, is generally a step too far tor most of them. To ease the problem, Alliant is discussing possible financing arrangements with other organizations. ENERJi & KOJENERASYON DÜNYASI
RkJQdWJsaXNoZXIy MTcyMTY=