Energy, Vol.77, 220-225, 2014
Exploitation of the waste-heat from hydro power plants
This paper presents the possibility of exploiting low-temperature heat from the generators' cooling system within a hydro power plant, using a HTHP (high temperature heat-pump) that enables heating at up to 85 degrees C. The results based on theoretical calculations are presented for heat-flows, the powers of the compressors, and COP (coefficient of performance) values for the cases when using the refrigerant R717 and a single stage high pressure compressor (up to 50 bar) under varying operational conditions. Real possibilities are presented for heat production based on measurements of a closed cooling system of generators, thus showing that the total efficiencies of generators can be enhanced by up to 1% whilst reducing the electricity consumption during the electric heating of buildings. In addition, the simulations of cost and revenue, and cumulatively discounted cash-flows of the investment in HTHP are presented using the MS Excel computer program. The payback period for the investment in a 500 kW high-temperature heat-pump for exploiting low-temperature heat of the generators' cooling system would be approximately 2 years for the case of heating the commercial buildings of the hydro power plant, and 7 years for the case when heating the fluid within the nearby district heating systems of urban settlements. (C) 2014 Elsevier Ltd. All rights reserved.