District Heating/Cooling Feasibility, City of Devils Lake, North Dakota

摘要

The City of Devils Lake took over the operation of a district heating system originally built and operated by the Otter Tail Power Company. This was a steam system with heat supplied with cogeneration from the production of electricity. The system was small, but the engineering was good, it used a two pipe, return condensate system. It was originally designed to burn coal as fuel, it was later converted to oil, and then to natural gas. Most of the business district, a number of institutions, and public housing buildings were carried by the district heating system. The search for less expensive fuel included solid waste, but the amount was insufficient to carry through the cold winters. Agricultural waste in the form of durum wheat straw is available in abundance. Tests have shown that pound for pound the straw had a higher BTU content than local coal. Contracts have been made with local farmers to deliver straw bales or rolls at prices attractive to both parties. The system is now operating.