11. December 2023

Grid-friendly use of heat pumps leads to a reduction in grid expansion costs

RLI analyses the effects of increased flexibility of heat pumps through higher output and heat storage capacity

Illustration: flexibility of heat pumps © RLI

Delayed expansion of the electricity grids jeopardizes the rapid implementation of the energy system transformation. More flexibility through heat pumps and heat storage in the electricity grid could counteract this and compensate for delays. This is the result of a short study by the Reiner Lemoine Institute (RLI). The scientists’ calculations show that the grid-friendly use of heat pumps leads to a reduction in grid expansion costs.

The transformation of the energy supply system is taking place at a decentralized level in particular and requires a major expansion of the electricity distribution grids. However, obstacles such as acceptance, a shortage of skilled workers and long planning processes are leading to delays in grid expansion. How can the energy system transition be accelerated despite these hurdles? The RLI’s short study investigated the effects of heat pump flexibility in combination with heat storage systems on the energy system transition. The result: In two modeled scenarios in which heat pumps are used flexibly and in a grid-friendly manner, grid expansion costs are reduced. This effect is particularly evident in low-voltage urban grids. This is where the greatest savings potential lies.

Investments are also required so that heat pumps and heat storage systems can be used flexibly. And these could be worthwhile, as another result of the study shows. The total costs of grid expansion and investment could even be reduced overall.

The researchers calculated three scenarios for the study. They differ in terms of the flexibility that heat pumps can provide. In the “No-Flex”-scenario, heat pumps cannot be operated flexibly. The “Flex”-scenario offers a medium degree of flexibility and the “Flex+”-scenario offers a high degree of flexibility. According to the calculations, the most favorable scenario is the “Flex”-scenario with medium flexibility. In this scenario, grid expansion costs could be reduced by 3.7 percent (equivalent to 1.33 billion Euros).

At the same time, the modeling shows that the heat pumps in the “Flex”-scenario can be dimensioned smaller due to the heat storage tanks. This would reduce the costs for heat pumps and storage tanks by 0.46 percent (0.51 billion Euros) compared to the “No-Flex”-scenario, despite additional investments in heat storage tanks. As a result, the use of flexible heat pumps with storage could save a total of 1.84 billion Euros – and partially compensate for the delay in grid expansion.

The calculated scenarios are embedded in the framework of a medium-term scenario on the way to a fully renewable energy system. The data was created using an open source tool and contains information for the electricity, heating, mobility and gas sectors.

The short study was commissioned by the Reiner Lemoine Foundation.

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