The Return of Coal-Fired Combined Heat and Power Plants: Feasibility and Environmental Assessment in the Case of Conversion to Another Fuel or Modernizing an Exhaust System

Abstract

Large city-scale coal-fired combined heat and power (CHP) plants are one of the main contributors to greenhouse gas emissions. The motivation is to find a way to decrease the contributions in the most feasible way possible. The importance of this study is that it presents a methodology for comparing scenarios from both environmental and economic points of view. The scenarios aim to enhance the environmental performance of combustion flue gas-treatment units. The scenarios include installing an advanced electrostatic precipitator (ESP), a hybrid system comprising ESP and a bag filter, a combined cyclone and baghouse filter, a hybrid baghouse filter with novel electrostatic tissue, a wet flue gas desulfurization (WFGD) scrubber, a WFGD with (NH4)2SO4 technology, and fuel conversion (incl. biomass). Each of the scenarios is evaluated according to (a) primary energy consumption, (b) capital (CapEx) and operational (OpEx) costs, and (c) the obtained environmental effect (decreasing emissions of particulate matter (PM), CO2, SO2, and NOx). Adopting biomass waste decreases CO2 emissions by 50%. PM from the coal-fired boiler with particle filtration is lower compared to biomass but is two times higher than that from natural gas. Using advanced filters for a CHP plant decreases total emissions and PM by 2100–2800%. The largest effect on air quality is achieved by filtration and WFGD, with emissions decreasing by 43%. Primary energy consumption is maximal in fuel conversion and ESP scenarios. The conversion to limestone-based WFGD or the installation of a hybrid filter separately are the most viable options, totaling EUR 14.2 billion of CapEx. However, combining several technologies is essential to increase the quality of flue gas treatment.