Preventing capacity exceedance on existing local grids when heat pumps replace conventional heating systems

Abstract

In the residential sector there is a high energy saving potential, especially regarding heat demand. A promising energy technology is the heat pump. It operates at a higher efficiency than conventional heating systems and it eliminates the need for natural gas and as a results less primary energy is consumed and less CO2 is emitted. The most common heat pump types use electricity. This means that heat pumps cause an additional load on the electrical grid. This additional load causes demand peaks that might exceed the current grid capacity. In that case not all heat demand is satisfied. In order to satisfy all heat demand grid capacity exceedance should be prevented. A predictable solution would be to reinforce the grid capacity by replacing transformers and cables, however this is relatively expensive. Therefore other measures are assessed regarding their ability to prevent capacity exceedance and their costs. Besides grid capacity expansion also thermal energy storage, heat demand reduction, and heat demand shifting are assessed. Additionally limiting the number of heat pumps is included. Grid capacity expansion, heat demand reduction and thermal energy storage, when implemented individually, can prevent capacity exceedance. Based on their annualized investement costs, capacity expansion and limiting the number of heat pumps are the least expensive measures at 40 resp. 0 €/household/year. Heat demand reduction and thermal energy storage and far more expensive at 1,100 resp. 700 €/household/year. When all the costs are included, which are the annual change in energy costs and the annualized investement cost for the heat pump and measure, then grid capacity expansion and limiting the number of heat pumps are the least expensive at 690 resp. 690 €/household/year. The annual costs with heat demand reduction and TES are 1,090 resp. 1,560 €/household/year. Primary energy saving and CO2 mitigation is achieved with the implementation of heat pumps. The lowest specific costs for primary energy saving and emission mitigation costs are found for heat demand reduction with 120 €/MWhprimary saved and 0.60 €/kg CO2 mitigated. Under the used base assumptions shiftin to heat pumps might not be economically viable, if all costs are included and charged to the end-consumer. The viabitily can be improved by lower investment costs, subsidies, larger price difference between electricity and gas and improving of the coefficient of performance. Also investment costs of measures can be reduced by finding combinations of measures and allocating measures to specific households.