Heating with wood waste: is it worth switching to pellets?

Homeowners who opt for a pellet heating system kill several birds with one stone.

Heating with wood waste: is it worth switching to pellets?

Homeowners who opt for a pellet heating system kill several birds with one stone. Especially when they want to replace oil as an energy source, which has become so expensive.

Wouldn't it be wonderful if you could actually recycle useless industrial waste for heating? And thereby replace the fossil fuels oil and gas that have become so expensive? That works with wood pellets. They are made from wood waste such as sawdust and wood shavings.

On the one hand, this recycling is good for the environment, say some. They consider the pellets to be sustainable and CO2-neutral. On the other hand, pellet heating systems and stoves are criticized by environmentalists because of their emissions.

How does a pellet heating system work?

There are different ways of heating with pellets. First of all, a pellet heating system should not be confused with a single pellet stove. It is right in the living room and has a small storage container for one or more daily rations of wood pellets. Its heat is released directly into the room air - just like with a normal wood-burning stove.

An alternative are water-bearing pellet stoves that use part of the energy to heat water. Excess heat is routed via a pipe system to a buffer storage tank, from where radiators are supplied and hot water is provided for the bathroom and kitchen. Both variants are therefore additions to an existing heating system.

The pellet central heating, on the other hand, supplies the whole house. She needs a storage room for the much larger amounts of heating material. Oil heaters are therefore often replaced by pellet stoves, because the oil store can be converted into a pellet room. For comparison: When burned, one kilogram of pellets produces approximately the same heating content as half a liter of heating oil, according to the German Energy Wood and Pellet Association (DEPV).

For which houses is a pellet heating system an option?

"Pellet heaters are suitable for generating space heating in almost all types of buildings, as they can also cope in older buildings with high flow temperatures, where the heat pump would consume a lot of electricity," says Martin Bentele, Managing Director of DEPV. Pellets are therefore used in detached houses as well as in large residential complexes.

How much does pellet central heating cost?

They cost two to three times as much as new oil and gas heating systems: According to DEPV, central heating costs at least 25,000 euros. However, there is funding for this via the Federal Funding for Efficient Buildings (BEG).

The standard grant is 10 percent of the cost. In the case of particularly low-emission biomass plants, the subsidy increases by five percent. If an oil heating system, a night storage or coal heating system, a gas heating system or a 20-year-old gas central heating system is replaced, the subsidy rate increases to 20 percent.

Anyone who combines pellet heating - for example with solar thermal energy or a heat pump - receives a subsidy of up to 35 percent. And if you rely on low-dust wood firing, there is a so-called innovation bonus of five percent for the time being until the end of 2022.

There may also be regional funding pots. The non-profit consulting company Co2online offers a free subsidy check online.

How are the prices for the pellets developing?

The pellet prices are largely dependent on the level of the price for waste wood. "In the last decade, the pellet price has been characterized by low dynamics. The average annual price increase from 2012 to 2021 was only 0.24 percent," says Martin Bentele. "Adjusted for inflation, prices even fell by 1.44 percent."

However, the unrest on the energy markets is also affecting the pellet market to an unforeseeable extent. Uncertainty among consumers has led to many hoarding pellets, leading to a sharp increase in demand. Together with rising raw material and production costs, the German Pellet Institute therefore recorded a price increase for wood pellets to 13.66 cents per kilowatt hour in August.

What are the advantages of pellet heating?

Pellet heating systems are often an obvious replacement for oil and gas heating systems. The existing lines and radiators can continue to be used, and the pellets can be combined with other regenerative energy sources such as solar thermal energy. When replacing oil heaters, the room in the oil store can be used for the pellet tank.

The supporters also see the eco-balance of the pellet heating systems as a major advantage. "Wood is a renewable and domestic raw material, the supply of which is higher in German forests than in any other EU country," says Martin Bentele. "Pellets are made from the waste wood that accumulates in the sawmill. They burn CO2-neutrally because the trees have previously converted carbon dioxide into oxygen."

But heating with wood is not without controversy because of its fine dust pollution. How sustainable and future-proof are pellet heating systems?

For Martin Bentele, the case is clear: Pellet heating systems usually meet the legal requirements for keeping the air clean in the first regulation for the implementation of the Federal Immission Control Act (1st BImSchV). In practice, a chimney sweep measures this twice a year.

However, the question of sustainability is also a question of the origin of the pellets: "If the pellets are made from waste products in the sawmills, that's fine. But not if whole tree trunks are made into pellets," says Stefan Materne from the energy team at the consumer center. He also considers the excessive demand for pellet stoves and the fuel from industry, combined heat and power plants and private consumers to be problematic.

"When the pellets are no longer just made from the sawdust in wood processing, come to Germany from overseas or valuable wood is turned into pellets, then the limit of the expansion of pellet boilers has been reached," says Materne. At the moment, however, pellet heating systems have a comparatively small share of the heating market - and therefore continue to receive funding with the aim of spreading this type of heating more widely.

How do you recognize a low-emission pellet heating system?

The Federal Environment Agency recommends heating systems with condensing technology. In addition to the normal energy yield, they also use the heat contained in the exhaust gas. Pellet condensing boilers can therefore achieve efficiency class A. Simple pellet boilers are in efficiency class A. It makes sense here to ensure that the energy efficiency index is as high as possible, at around 120 percent. And a so-called dust separator can reduce the pollutant emissions from pellet boilers.

How can I find eco-friendly manufactured pellets?

It is best to buy pellets from the region - their transport routes are short. The Federal Environment Agency advises homeowners to ensure that the pellets come from sustainable forestry. This can be recognized by the FSC or PEFC seals. Wood pellets should have quality class DIN Plus, ENplus or DIN EN 17225-2 A1. The quality requirements are the highest for ENplus pellets.

(This article was first published on Monday, September 19, 2022.)