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CHEAP AND EFFICIENT APPLICATION OF RELIABLE GROUND SOURCE HEAT EXCHANGERS AND PUMPS

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Warming up to promising sustainable heating and cooling technology

European buildings are sitting on a gold mine – geothermal energy. Now, major cost reductions in technology together with decision support for experts and novices alike should encourage uptake with important benefits for the environment.

Energy

Heating and cooling accounts for about half of the EU’s overall energy consumption. About 75 % of that is still supplied by fossil fuels. Clearly, enhancing the sustainability of heating and cooling could significantly reduce greenhouse gas emissions and mitigate climate change.The ground underneath buildings can provide heat in the winter and cooling in the summers. However, widespread adoption of geothermal heating and cooling has faced economic and technical challenges. The EU-funded Cheap-GSHPs project has overcome these barriers and simultaneously delivered a freely available decision support tool to help prospective users evaluate options.

Technological advances lower cost and enhance utility

According to project coordinator Adriana Bernardi: “Cheap-GSHPs targeted a 20-30 % reduction in total cost through improved design and installation of more efficient and safe shallow geothermal systems.” The team developed helicoidal ground source heat exchangers (GSHEs) with a smaller external diameter of the heat basket to facilitate drilling at greater depths. They complemented the design with a modified dry drilling methodology. Cheap-GSHPs also designed coaxial steel GSHEs and improved existing vertical borehole installation technology, the latter of which resulted in a patent application. Multiple pilots of both technologies across Europe demonstrated increases in thermal energy exchange of 20-40 % when compared to the state of the art.A novel heat pump using CO2 as a refrigerant for high-temperature terminals and piping was developed and a patent application submitted. It eliminates the need to replace conventional radiators and piping to accommodate the lower temperatures of typical GSHE heat pumps. Installed under the supervision of UNESCO in the Nikola Tesla Technical Museum, Zagreb, the heat pump will significantly reduce the costs for retrofitting buildings, particularly historical and cultural ones.

Equally accessible to novices and experts

Software and modelling tools developed to aid in design optimisation were also critical components of Cheap-GSHPs’ decision support system (DSS). The DSS represents a first of its kind, end-to-end feasibility assessment for shallow geothermal installations that includes drillability assessment, climatic data, building loads, heat pump/exchanger sizing, and regulatory structures. According to Bernardi: “The databases and tools enable creation of EUR/kW maps comparing the Cheap-GSHPs borehole heat exchangers with traditional ones to assess the feasibility of shallow geothermal energy.”

Shallow geothermal for a sustainable future

An important way to enhance the impact of the technology was raising public awareness. The project developed a technical brochure and a technical training manual in eight languages, as well as a technical handbook in three languages focused on historical buildings. Together with the DSS, all are freely available on the project website. In an innovative and highly unusual action, the project also offered free workshops and training courses in countries throughout Europe in the language of the country.Bernardi summarises: “Cheap-GSHPs has now made shallow geothermal energy solutions more affordable in soil regions with high drilling costs thanks to an investment cost reduction of 20 to 30 %.” The project also delivered the new heat pump for the retrofitting of existing and historical buildings and the DSS. Together, Cheap-GSHPs’ innovative, cost-effective and energy-efficient technologies and tools could significantly enhance uptake and reduce CO2 emissions associated with heating and cooling Europe’s buildings, old and new.

Keywords

Cheap-GSHPs, heat, energy, geothermal, cost, cooling, heating, shallow, buildings, decision support system, DSS, installation, heat pump, tools, historical, drilling, borehole, ground source heat exchangers, GSHE, coaxial steel, helicoidal ground source heat exchangers, emissions, patent

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