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> Forest Report 2015 Condition and Use of Swiss Forests FOEN / WSL 2015
6.9 Wood energy
Oliver Thees and Claire-Lise Suter Thalmann
> In Switzerland, wood is currently the second most important renewable energy source after hydropower.
> In 2012 wood met 4 per cent of Switzerland’s total energy requirements and about 8 per cent of its heating requirements. These percentages have risen considerably since 2005.
> Wood’s contribution to Switzerland’s total energy production is low, and obtaining it is relatively expensive.
This means that using this raw material as a source of energy should be especially efficient and value-adding.
Use of energy wood
In 2011, the Federal Council and parliament decided to phase out nuclear energy step-by-step as a first move towards an energy transition. The aim is to implement measures to fill the gap left due to pulling out of atomic power by improving energy efficiency and using sustainable energy sources. This political decision was a result of the environmental and atomic power catastrophe in Japan (Fukushima, March 2011) and has, in the meantime, led to wood energy becoming more impor- tant. Since 2000, the use of energy wood in Switzerland has been steadily increasing. In 2012, it accounted for 4.2 per cent of the total end energy consumption, making wood the second most important renewable energy source after hydropower.
The energy transition will mean that, in the future, there will be a higher demand for wood and other renewable energy sources, and thus a larger proportion of the end energy con- sumption will be in the form of wood.
Wood can be used to produce heat, electricity and fuel.
In 2012, an estimated 4.3 million m3 (section 6.7) of wood was used as a source of energy. With this, about 8,103 giga-watt hours (Gwh, 29.2 petajoules) of useful energy were produced.
Wood was used mostly to produce heat: 7,694 GWh (27.7 peta- joule) of usable heat. A further 410 GWh (1.5 petajoule) of electricity was produced in special furnaces and combined heat and power plants (Fig. 6.9.1). About 95 per cent of energy wood is used for producing heat, covering about 8 per cent of Switzerland’s total heating requirements. Energy wood is in the form of logs, chips and pellets. The demand for logs has remained the same since 2005, but the demand for chips and pellets is constantly increasing. Thanks to these energy wood products, automatic furnaces have increased in number. From the point of view of air pollution control, these are unproblem- atic because they have, among other things, air filters and lose less energy than the numerous, normally smaller and manu- ally operated wood-stoves.
Wood is a climate-friendly source of energy because trees bind as much CO2 as is set free when the wood is burnt. The CO2
balance is improved when fossil energy sources are replaced by wood (section 1.4). Nevertheless, more particulate matter, nitrogen oxides (NOX) and volatile organic compounds (VOC) are released. However, the way wood is used as a source of energy and careful planning when designing the heating can help to minimise the negative effects and environmentally optimise the use of wood as a source of energy.
Potentials of energy wood
The source of wood used for energy varies. Forest wood, the residuals of industrial wood (especially slats, shavings, sawdust and bark), woodland fragments and waste wood are all used. Forest wood accounts for 60 per cent, which is the
Fig. 6.9.1 Total amount of wood used for energy in Switzerland between 1993 and 2012 for different types of furnace and heating (in million m3). Source: FSO and FOEN 2013
1.0 2.0
0 3.0 4.0
1.5 2.5
0.5 3.5 4.5 5.0
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 Special furnaces
Automatic furnaces >50kW
Heating for buildings Heating for individual rooms
Million m3
> 6 Social Economy 6.9 Wood energy 119
largest proportion. It consists of different parts of the trees:
trunks, branches, twigs and needles. Basically, the wood mar- ket decides about which wood is to be used for energy, and also about cascade use. This involves using wood first as a material, for example as wood for the construction or furni- ture industries, and then for energy. Cascade use thus means using the resource several times. Using wood as a material binds CO2, and its ensuing use as a source of energy replaces fossil resources and therefore saves CO2. To optimally use the resource wood, this cascade use should be promoted.
Given the current wood market situation, it is difficult to implement, especially as the demand for beech stemwood for use in the manufacturing industry is low and the price for wood as a source of energy is attractive. This situation has led, since 2009, to higher quality sorts of wood increasingly either been burnt, because there are no alternatives, or not even harvested.
Currently, an estimated 2.0 to 2.5 million m3 of Swiss forest wood are used annually as energy. This is equivalent to about 40 per cent of the trees felled every year. The sustaina- ble usable wood energy potential in the Swiss forest depends significantly on how much wood is felled – energy wood is often a by-product – and how the market for wood as a source of energy develops.
According to the latest estimates from WSL, on average of different scenarios of use, about 4.0 million m3 of forest energy wood (solid wood greater than 7 cm in diameter and brushwood with bark) could be harvested each year (Fig. 6.9.2;
Thees et al. 2013), equivalent to an energy volume of about 12,500 GWh (45 petajoule). An estimate from FOEN is that
about 3.1 million m3 of wood could be produced for energy (FOEN et al. 2014). In Switzerland, the largest additional potential for wood as a source of energy is to be found in the forests in the Alps and on the Southern slopes of the Alps.
This wood is on very steep terrain, and is difficult to harvest and thus expensive (section 5.2). Ultimately, Switzerland’s forest wood is limited. The contributions of wood and other biomass to the total energy production are currently rather low and will remain so in the future. For wood nevertheless to make a maximum contribution to the energy transition, the available potential must be tapped to the full by ensuring the most efficient and value-adding use of the raw materials. One approach is the trend towards increased use of combined heat and power.
Fig. 6.9.2 Energy wood potentials in Switzerland and in individual forest regions up to 2026 where the scenario of use is ‘as until now’. Source: Thees et al. 2013
0 1.0 2.0 3.0
0.5 1.5 2.5 3.5
Million m3/year
Softwood Hardwood Total Jura
Swiss plateau
Pre-Alps
Alps Southern slopes
of the Alps Switzerland
