Energy transition in heating: Expansion of wood use counterproductive for climate and health
Burning wood produces greenhouse gases and air pollutants that are hazardous to health.
Source: Marco2811 / Fotolia.com |
The heating of rooms accounts for about 70 percent of the energy consumption of private households in Germany. In order to mitigate the disastrous consequences of climate change for us humans, a reduction in this consumption and a complete switch from natural gas and oil to renewable energies is essential. However, if this were to significantly increase the use of wood, it would have far-reaching negative consequences for health and climate protection.
The burning of wood in small private combustion units, such as fireplaces and tiled stoves or wood-fired boilers, already accounted for 18 percent of German emissions of fine particulate matter (PM2.5) in 2020 – almost as much as road traffic. However, at least a halving of PM2.5 emissions would be necessary to approach the recommendations of the World Health Organisation (WHO) for ambient air. Air pollution – and especially particulate matter – is one of the greatest environmental threats to human health, along with climate change.
Further expansion of wood combustion would also be counterproductive in terms of climate protection. The amount of carbon stored in German and European forests has been declining for years, and it can no longer be reliably assumed that the carbon released when wood is burned will be promptly recaptured. However, for us to meet our climate targets, forests will need to sequester even more CO₂ in the future than they do now. To do this, more wood must grow back than is removed from the forest – and this must be done in the face of increasing risks of droughts and forest fires. If wood is used, it should first be for durable products, such as furniture or lumber, so that the CO₂ stored in the wood is not immediately released back into the atmosphere by burning. Only wood that is not (no longer) usable for such products should be burned, and then for purposes where other renewable energies, such as heat pumps powered by green electricity, are only marginally suitable – such as high-temperature processes in industry – or for applications that can meet high emission standards, such as large combined heat and power plants.
Wood should only be used to heat buildings in exceptional, well-justified cases where there is really no alternative. Buildings should be heated primarily with the help of heating networks or heat pumps, which can now also efficiently supply partially renovated existing buildings, after energy refurbishment has minimised the heat demand. Where a heat pump alone is not sufficient, hybrid heating systems are a solution, in which the heat pump provides most of the heating and a pellet boiler provides support on the coldest days – even this combination saves a lot of fuel.
The UBA (German Environment Agency) therefore recommends the following 4-point plan to protect health and the climate:
Point 1: State subsidies for wood heating systems, whether with logs, wood pellets or briquettes, should be discontinued by the end of 2023 and the money used instead to promote energy-efficient building renovation and heat pumps.
Point 2: In the regulation currently being planned by the legislator to use at least 65 per cent renewable energies in new heating systems, preference should be given to heat pumps and heating networks.
Point 3: The limit values for particulate matter in ambient air should be tightened in the course of the upcoming revision of the EU Air Quality Directive based on the recommendations of the WHO.
Point 4: The emission limits for wood heaters should also be tightened in the EU and Germany.
