GREEN LOCAL HEATING WITH GEOTHERMAL HEATING
TECHNICAL SOLUTION
Scope I – the direct emission volume
The Scope I emissions arising from near-surface geothermal energy, which are caused directly by the local heating network operator as a result of the operating activities and are therefore also responsible for and controlled, essentially relate to drilling and pumping processes. Compared to conventional fossil fuels, however, the direct emission volume is comparatively low.
In near-surface geothermal energy, heat pumps and the refrigerants used in them play a central role. In principle, they have a high global warming potential, which can lead to significant greenhouse gas emissions, especially in the event of leaks or improper disposal.
Scope II – the indirect and “bought” emission volume
Scope II emissions, which account for the largest share of global greenhouse gas emissions, result as indirect greenhouse gas emissions primarily from "purchased" energy, such as electricity, district heating or cooling. The main difference to Scope I emissions is that although they are generated outside the system limits that can be directly determined by the company, they are consumed by the company itself.
In the case of near-surface geothermal energy, the Scope II emissions include the electricity "purchased" to operate the heat pumps. In the event that the brine-water heat pump is operated with electricity that comes entirely from renewable energy sources such as solar energy, wind energy or hydroelectric power, the CO2 emissions of the operation of the heat pump are almost zero.
Near-surface geothermal energy - technical principle and implementation
In contrast to deep geothermal energy, shallow geothermal energy is generally only drilled to a depth of around 100 metres. Depending on the geographical composition of the ground, there is also the option of laying the geothermal probes horizontally in trenches.
The plastic pipes filled with a heat transfer medium are inserted into the borehole and laid in a loop. The thermal energy (geothermal heat) is absorbed by the carrier medium and sent to the evaporator. Here is a refrigerant that absorbs the energy and evaporates at very low temperatures. The steam obtained is then compressed in the compressor in order to generate a higher temperature level. The superheated refrigerant vapor is transferred to the existing heating system at the condenser, where it cools down further and is liquefied again through this condensation process.
The cooled heat transfer medium is then pumped back into the ground via the plastic pipes, where it can absorb thermal energy again. The heat pump is usually installed between the heating system and the heat emission system. The heating system used can be a conventional system with a boiler and/or a hot water tank. It is efficient, environmentally friendly and opens up significant savings potential in terms of energy costs.
Location and sizing of the heat pump
In addition to the size of the building, the size of the heat pump depends primarily on the required heating requirement. Even a 50kW brine-water heat pump with a volume of approx. 3 square meters can easily be set up in a conventionally dimensioned house connection room.
In addition, there is also the possibility, especially in apartment buildings, to set up the heat pumps installed in a separate container outside of the building.
When selecting the electricity for the heat pump, which depends on various parameters, DGC strives to choose a tariff that has the highest possible share of renewable energy in order to maximize the sustainability of the system.
permits
DGC obtains the permits required for the installation and operation of near-surface geothermal energy from the responsible local authorities.
Since near-surface geothermal energy can also have an impact on soil changes, we work closely with the responsible authorities right from the planning phase in order to be able to rule out negative effects on the environment, as well as on flora and fauna.
Increasing resilience through the use of geothermal energy
In the context of the upcoming energy transition, decentralization of the energy supply and digitization are determining factors. In this environment, the resilience of the technical systems on site, i.e. the ability not to fail completely in the event of a partial failure, is becoming increasingly important.
Housing companies that opt for "local heating through geothermal energy" for the heat supply of their properties also gain greater resilience. Since the power supply of the heat pumps can be regulated individually with the regional electricity supplier, there is the possibility of obtaining a more favorable electricity tariff over a defined time window in which no supply is required.
In addition, in the event of a partial failure of the power grid, power buffer storage can bridge the lack of supply to the heat pumps and thus further increase the resilience of the technical system.
Since the power supply for the heat pumps is primarily provided by local electricity providers, network losses, which mainly result from the ohmic resistance of the transmission media, would be significantly reduced.
Statutory price development of the CO2 tax
In 2019, the climate cabinet of the federal government presented the so-called climate package, which also includes a national emissions trading system for the fuels used in the building sector. The system, which was introduced in January 2021 and is based on the Fuel Emissions Trading Act, started with a CO2 tax of 25 euros per tonne of carbon dioxide (CO2) emitted, which was set by law for 2021. In the introductory phase of 2021-2025 defined in the law, emission certificates can be purchased at a fixed price. A certificate thus entitles the holder to emit one tonne of greenhouse gases per calendar year. From 2026, a price corridor will be specified for the first time.
The aim of this trading in emissions rights is to levy a fee per tonne of greenhouse gases on the emission of greenhouse gases from the burning of fossil fuels (eg oil and gas) in order to promote the switch to regenerative energies. The gradual increase in the CO2 tax on fossil fuels is likely to lead to a significant price increase in the future, which is likely to make the use of these fuels increasingly unattractive and thus also create an incentive to reduce emissions.
By the end of 2022, property owners could pass on the full cost of the CO2 tax to their tenants. From January 2023, the CO2 costs for residential buildings resulting from the Fuel Emissions Trading Act (BEHG) will no longer be borne solely by the tenant, but also by the landlord. The breakdown is based on the CO2 emissions per square meter of living space per year. In the case of residential buildings with a particularly poor energy balance (limit of 52 kg CO2 emissions per square meter and year), the tenant only pays 5% of the fee. The landlord has to bear the remaining 95% of the fee. If, on the other hand, the building meets the current new building standard EH 55, the tenant continues to bear the CO2 tax alone. The CO2 consumption of a property is stated in the annual bill from the energy supply company.
In order to reduce the building's CO2 emissions per square meter of living space and year, owners can, for example, carry out cost-intensive insulation measures on the building's outer shell. Exorbitant costs can arise, especially for older properties with insufficient thermal insulation. However, if the supply is via a DGC local heating network, there are no costs for either tenants or landlords.