A recent study by Finland’s VTT Technical Research Centre has concluded that nuclear energy can become a viable option for replacing fossil fuels in heat production. The study, Evaluation of Life Cycle CO2 Emissions for the LDR-50 Nuclear District Heating Reactor looked at the LDR-50 low-temperature nuclear reactor, which is designed for the Finnish and European district heating markets, as an environmentally sustainable heating option for the 2030s.
The LDR-50 reactor is being developed by Steady Energy, which was spun out in May 2023 from VTT. The LDR-50 reactor module comprises two nested pressure vessels, with their intermediate space partially filled with water. When heat removal through the primary heat exchangers is compromised, water in the intermediate space begins to boil, forming an efficient passive heat transfer route into the reactor pool. The system does not rely on electricity or any mechanical moving parts, which could fail and prevent the cooling function. The innovation was awarded a patent in 2021.
The study evaluated the carbon footprint of the LDR-50 heating plant and compared it with conventional heating fuels, direct electric heating, and heat pumps. The results of the analysis showed that the life cycle CO2 emissions are low, although there are still significant uncertainties related to the construction phase, due to missing data. The analysis, which also extended to other adverse environmental impacts, concluded that significant reductions in CO2 emissions can be achieved by replacing fossil heating fuels with nuclear energy. The technology is considered a viable option alongside biofuels and heat pumps. The overall environmental impacts are low, and the production does not compete for low-carbon electricity or scarce natural resources.
VTT noted that the reliability of the analysis could be improved with the better input data that would become available as the development proceeds. According to the study, the largest emission reduction potential lies in countries where energy production still relies heavily on coal and natural gas, and district heating holds a large market share. “Such countries include, for example, Estonia, Poland, Czechia, Slovakia, and Ukraine. This description also applies to Denmark and certain parts of Germany, but because of the local political climate, it is not likely that nuclear reactors will be built in these countries within the foreseeable future.”
The study said other advantages and drawbacks needed to be considered. “Nuclear reactors are subject to complicated licensing procedures, and require commitment to high safety standards and management of radioactive wastes. The initial investment costs for constructing the heating plant are high, even though the operation is relatively cheap. On the positive side, the security of supply for nuclear energy is high, as fuel for several years of operation can be stored on site.”
Increased demand is likely to lead to competition between different applications, in which case using low-carbon electricity and wood-based fuels to produce low-temperature heat for residential and office buildings may no longer be seen as the most efficient use of limited natural resources. “This is where the advantages of the nuclear option also stand out. The environmental impacts are low in all categories, not only for CO2 emissions, and the production is decoupled from electricity and the upcoming hydrogen markets,” the study noted.
The first LDR-50 units are planned to be built in Finland, where the CO2 emissions from the heating sector are already declining as fossil-fired plants are switching to biofuels. “The long-term sustainability of this option, however, has been questioned, due to adverse effects on biodiversity and carbon sinks. For this reason, the large-scale utilisation of wood-based fuels is no longer considered a viable long-term, but rather a transitional solution. It is possible that tightening environmental regulations will put an end to all combustible fuels being used for district heating within the following decades.”
Heating of residential buildings and other premises consumes a lot of energy in countries with a cold winter climate. In Europe, the homes of 60m people depend on 3,500 local district heating networks.
