Climate change and the imperative to reduce greenhouse gas emissions are central themes on the global stage. The European Union (EU) has embarked on an ambitious journey with its Green Deal, which includes the commitment to achieve climate neutrality by 2050. A critical component of this endeavor is the transition in the heating sector, particularly at the communal and district levels, where heat pumps emerge as pivotal tools in achieving this transition.
The EU Green Deal 2050
The EU’s Green Deal, introduced by the European Commission in 2019, presents a comprehensive policy framework addressing climate change and the pursuit of a sustainable future. It encompasses a wide array of measures aimed at combatting climate change, advancing renewable energy, enhancing energy efficiency, promoting circular economy practices, preserving biodiversity, and fostering sustainable agriculture.
One of the Green Deal’s central pillars is the transformation of the heating sector. Given that nearly half of Germany and the EU’s primary energy consumption is attributed to heating and cooling, this transformation assumes paramount importance in achieving both national and global climate targets. The shift towards sustainable and environmentally friendly heating and cooling systems is vital to curb greenhouse gas emissions and attain climate neutrality.
Beyond its technical aspects, the Green Deal considers the social dimensions of this transition. Moving from a fossil fuel-dependent society to a sustainable economy must ensure social security. The Green Deal incorporates the social dimension by safeguarding societal needs, promoting equitable measures, and addressing the challenges associated with this transition.
The EU Green Deal represents an ambitious and holistic strategy to address climate change while building a sustainable future. The interconnectedness of climate neutrality, heat transition, and social protection is a key strategy for successfully addressing the climate crisis and shaping a sustainable European society.
The Communal and District Heat Transition
The transition of communal and district heating systems is a formidable challenge in the pursuit of national and international climate objectives for decarbonizing heat supply. Despite a notable increase in the share of renewable energy in total energy consumption, particularly in Germany, the heating sector significantly lags behind the electricity sector, which already sources approximately half of its energy from renewables. Moreover, less than half of the heating systems installed in 2021 utilized renewable energy sources, whereas 76% of new buildings relied on renewable primary energy sources.
Given the typical lifespan of heating systems of approximately 20 years, achieving full decarbonization of the heating market by 2045 in Germany and by 2050 in Europe appears challenging. This is where the Communal Heat Transition comes into play, aiming to initiate essential decision-making processes through targeted heat planning. The challenge lies in strategic heat planning and the integration of implementation processes within municipal administrations and the real estate sector.
Several German federal states have already promoted the introduction of local heat planning, with future regulations expected at the federal level. The objective is to plan energy supply for buildings, trade, and industry based on renewable energies while simultaneously considering complete decarbonization.
Guidelines for municipal heat planning in Baden-Württemberg offer insights into the technical and economic aspects that must be addressed. These encompass analyzing opportunities for renewable energy utilization, determining required areas, identifying suitable heating center locations, and exploring available waste heat sources. Extending heating networks to rural areas not currently served is also part of the planning process.
These challenges underscore the complexity of urban heat transition. The development of networks and renewable energy sources necessitates a holistic approach to realize sustainable, eco-friendly, and climateneutral heat supply in municipalities and existing buildings.
The Heat Pump as a Central Element
The heat pump stands out as a pivotal component in advancing urban heat transition. Both ground-source and air-source heat pumps offer highly efficient and eco-friendly options for heating and cooling buildings, with the choice dependent on local conditions. It’s worth noting that, in addition to environmental heat, there’s often untapped waste heat potential from cooling processes or wastewater that can be integrated into heating networks.
A comparison between air-source and ground-source heat pump systems reveals that air-source systems typically require lower initial investments but may produce higher noise levels, potentially leading to conflicts in residential areas. In contrast, geothermal systems have a smaller physical footprint, longer lifespans, and, crucially, significantly higher efficiency. Geothermal systems’ higher efficiency, combined with borehole heat exchangers with lifespans exceeding 50 years, often results in superior economic efficiency. All heat pump systems share the common trait of producing substantially more heat energy from 1 kWh of primary energy (usually electricity), regardless of the chosen heat pump technology. This is reflected in the Annual Performance Factor (APF), representing the ratio of heat produced to primary energy consumed. Geothermal systems exhibit a seasonal performance factor of 4.9 in new buildings, compared to 3.5 for air-supported systems, indicating that a geothermal heat pump generates 4.9 kWh of thermal heating energy from 1 kWh of electricity. In some cases, the coefficient of performance (COP) for cooling can exceed 30, with the COP for geothermal heat pumps projected to reach 7.9 by 2050.
In addition to traditional heating networks with medium and low operating temperatures, cold networks, or energy networks, are gaining importance. These networks distribute source energy through the network within a temperature range of approximately 8°C to 16°C and enable decentralized heat and cold production in individual buildings. This technology integrates high-temperature waste heat from industries as well as low-temperature energy sources, such as waste heat from data centers and offices. These networks offer minimal heat losses, even over long distances, due to the proximity of network temperature to ground temperature, eliminating the need for costly insulation.
The versatility of heat pump technology, combined with various heat network options, plays a vital role in efficiently and ecologically implementing the heat transition and contributing to the decarbonization of the heating sector.
Is it profitable to store heat?
Traditionally and to this day, fossil fuels, particularly natural gas, have been stored and used for heating energy during the winter. However, the low energy density and economic value of natural gas make it challenging to distribute thermal energy, such as heating, over extensive heating networks at a national or European scale. Thus, addressing heat transfer and thermal energy storage at a local or decentralized level becomes imperative.
Considering the mismatch between the times when renewable energy is typically generated and when thermal energy is consumed, energy storage becomes crucial. This is particularly relevant when factoring in that electricity is the primary energy source for building air conditioning and is generated during the warm season, often through photovoltaic systems. This prompts the question of whether it is technically and economically viable to store this energy as electricity or thermal energy for the winter season.
In this context, soil and groundwater emerge as highly cost-effective and efficient options for seasonal thermal energy storage. According to the German Geothermal Association, the cost of storing air-conditioning heat can be significantly lower than conventional battery storage. Charging the geothermal storage in the summer using heat pumps can further enhance overall efficiency.
To fully optimize seasonal geothermal storage, higher storage temperatures would be desirable. However, current German water protection regulations impose temperature limitations, presenting a conflict of interest. It’s important to emphasize that using soil and groundwater as thermal reservoirs does not involve groundwater extraction but instead utilizes thermal storage capacity, making it environmentally benign.
Groundwater consumption would be unacceptable, especially considering the impending groundwater scarcity due to climate change.
Executive Summary
The EU’s commitment to achieving climate neutrality by 2050 places a substantial responsibility on energy providers, industry, and society as a whole. In this context, heat supply plays a pivotal role. Local and District Heating Planning serves as a tool to transform critical segments of the energy market toward climate-neutral solutions. Simultaneously, technical solutions like heat pumps offer a means to reduce CO2 emissions from both new and existing buildings. In light of these circumstances, resolute and consistent action is imperative to realize the ambitious goals we’ve set for ourselves.
References
1. DeStatis – Online Database of the Federal Statistical Office
2. Guideline for Action: Municipal Heat Planning – KEA-BW – Stuttgart 12/2021
3. Outlook on Potential Developments of Heat Pump Systems until 2050 – Inter-State University of Applied Sciences of Technology Buchs – Bern 11/2019