The two purposes of this study are to identify factors for the failure of 31% of community anaerobic digesters (CADs) in the United States through a case study of the development, operation, and shutdown of a $4.5 million CAD in Vermont, and to derive policy recommendations for sustainable development of CADs. While many studies have used aggregated data to assess the potentials, obstacles, and policy implications of on-farm biogas production, this paper contributes to the literature with a case study of a large CAD's investment and funding sources, feedstock utilization, energy output, and operating costs and revenues over multiple years. Empirical findings suggest that it is technically feasible to use cow manure and organic wastes from multiple sources to generate electricity, but the economic feasibility and returns depend highly on grants and subsidies for initial investments and on such factors as electricity price, feedstock availability and quality, and market price of renewable energy credits (RECs). Major reasons for the shutdown of this CAD, and likely a large proportion of other CADs in the country, include underestimation of technical problems and operating costs, overestimation of financial returns, and low REC price in the past several years. Future CADs should be invested in and operated by commercial enterprises and government subsidies, and public supports should be based on CADs' outputs such as electricity and utilization of their byproducts like waste heat and recycled nutrients. Also, the educational and research needs of nonprofit organizations could be met via collaboration with privately operated CADs.

这项研究的两个目的是通过对佛蒙特州450万美元CAD的开发，运营和关闭进行案例研究，找出导致美国31％的社区厌氧消化器（CAD）失效的因素，并推导CAD可持续发展的政策建议。尽管许多研究使用汇总数据来评估农场沼气生产的潜力，障碍和政策影响，但本文还是以大量CAD的投资和资金来源，原料利用，能源输出以及多年的运营成本和收入。经验发现表明，利用牛粪和多种来源的有机废物来发电在技术上是可行的，但是经济可行性和回报在很大程度上取决于对初始投资的赠款和补贴，以及诸如电价，原料供应和质量以及可再生能源信用（REC）的市场价格等因素。关闭该CAD的主要原因可能是该国其他CAD的很大一部分，其中包括对技术问题和运营成本的低估，对财务收益的高估以及在过去几年中REC价格较低。未来的CAD应该由商业企业和政府补贴来投资和运营，而公共支持应基于CAD的输出，例如电力以及其副产品的利用，例如废热和可循环利用的营养。也，