Evaluating the techno-economic impact of decarbonizing buildings by using borehole heat exchangers in comparison to fuel-based systems

The climate change, volatile geopolitical conditions, energy insecurity, and supply disruptions experienced lately have highlighted the need for a solid strategy to speed up the transition to green energy and reduce dependence on fossil fuels. Developing tools and methods for fast assessment of techno-economic, environmental and socioeconomic aspects of sustainable energy solutions will contribute to this goal. This paper presents results of a case study using an inhouse techno-economic analysis tool developed to provide access to detailed data settings, reflecting the most important technical as well as economic parameters of studied energy technologies. Five different energy solutions for heating and cooling of a specified building in a given geographical position and thereby economic environment have been assessed and compared using the inhouse analysis tool. Based on the proposed techno-economic framework, the energy efficiencies, costs, subsidies and negative CO2 emissions are estimated and used to identify the critical economic parameters on profitability and policy making recommendations. Using the coal-based heating system as reference case, the comparative study carried out shows the advantages and disadvantages of biomass and natural gas based boilers as well as the geothermal installation. Considering the environmental benefits of the renewable based energy resources, which will become a stronger market driver for every year. The results show that both air-source and ground source heat pumps are currently profitable under current subsidy schemes. The net present value is highly influenced by capital costs and subsidies. In the same way, natural gas prices significantly affect the net present value of gas boilers. As gas prices increase over 43 % of the current level in Poland, heat pumps become more attractive. Replacing a coal-fired boiler with gas will take up to years to pay-off. However, the air source heat pump and ground source heat pump will take longer to pay off, up to 10 years for the air source heat pump and 15 years for the ground source heat pump. The carbon intensity of the ground source heat pump (186 kg CO2 eq) is lower than the levels of the gas boilers (203 kg CO2 eq) and the air source heat pump (263 kg CO2 eq). Ground source heat pump system installation expects to provide a substantial saving of 58 % on CO2 emissions versus coal-fired systems. Air source heat pump P emits 267 kg CO2/kWh/year more than gas boilers, but emissions decrease drastically as the Polish power grid becomes greener in 2030 and 2040.