Material-flow analysis, energy analysis, and partial environmental-LCA of a district-heating combined heat and power plant in Sweden

Combined heat and power (CHP) plants are a great improvement over waste-to-energy incineration plants supplying only heat, and power plants supplying only electricity. The primary purpose of a functioning CHP plant however, may be to provide district heating services, and thereby its main output will be heat energy. This paper is a case study commissioned by Karlskoga Energi och Miljö AB (KEMAB in short; Karlskoga Energy and Environment) in the Värmland State of south-central Sweden, and focuses on the functioning of the CHP plant owned and operated by the company. The life-cycles of the fuels used by the CHP - household/industrial waste, bio-oil, light fuel oil, wood waste, wood chips, a slaughterhouse-waste-derived product and peat to generate 202,222 MWh of heat, 119,234 MWh of steam and 28,220 MWh of electricity have been studied, and the carbon footprint calculated for year-2016. Using two sets of emissions factors for the combustion stage of the life-cycle, as part of a data uncertainty analysis, the total emissions were 44,000 tonnes carbon dioxide equivalents (CO2-eq) and 58,000 tonnes CO2-eq respectively. A quasi-realistic scenario analysis in which plastics are not available for incineration and have to be substituted with alternatives has also been carried out, and while wood waste has been suggested as the best alternative with regard to greenhouse gas (GHG) emissions, availability permitting, a combination of alternatives has been mooted as the practical option.