Cost-optimal dimensioning of hybrid heat pump systems utilizing waste heat from hydrogen production for a kindergarten in cold climate

• Waste heat from hydrogen production was utilized in hybrid energy systems. • Cost-optimal dimensioning of hybrid energy systems for heating was examined. • Two district heating tariffs effects on dimensioning were analyzed. The growing need for environmentally-friendly energy solutions encourages the integration of various renewable energy sources in buildings. District heating (DH) systems, widely applied in northern and central European countries, are efficient in transforming and integrating renewable energy sources in large-scale energy systems. With the growth of hydrogen (H 2 ) production, there is great potential for utilizing H 2 production excess heat. However, the cost-optimal dimensioning of hybrid heat pump systems considering H 2 production excess heat is still in its infancy. This study examined the cost-optimal dimensioning of energy systems based on the 25-year life cycle cost (LCC). Two types of heat pumps, ground source heat pump (GSHP) and air-to-water heat pump (A2WHP) equipped with photovoltaic (PV) panels have been used in tandem with a DH system to provide heat to a kindergarten in the Nordic region. The comparison included two DH tariffs: the commercial DH prices from a DH company and the zero-emission DH price derived from waste heat generated during H 2 production. The results found that the GSHP with PV and waste heat from H 2 production has the lowest LCC. The utilization of H 2 production waste heat can decrease up to 10 % of HP dimensioning because of a lower DH price in the heating season.