Wood As An Energy Resource
A brief historical outline
Wood has been used by people since the dawn of time, since they were able to start fires themselves. Burnt wood heated rooms where people stayed, and was also used to prepare meals.
At the beginning of the industrial era (19th century), wood was also a basic energy resource – blast furnaces used charcoal to smelt iron from ore (as, for example, in Kuźnice in Zakopane), and steam engines (e.g. in locomotives) also used wood as fuel. People have therefore accumulated centuries of experience in using wood as an energy resource.
This knowledge is contained in old and modern scientific publications. The widespread use of natural gas, crude oil, brown and hard coal has reduced the demand for wood as an energy resource. In 2023 only about 10% of wood extracted from forests in Poland is intended for energy purposes – while 90% of wood is used in the production of about 30,000 different market and industrial products (mainly construction and furniture).
The return to the wider use of wood for heating purposes is caused by specific, unusual qualities as a fuel.
Specific values of wood as an energy resource
Wood is a renewable fuel, unlike non-renewable conventional fuels, i.e. gas, oil and coal. Carbon dioxide (CO2) and water (H2O) produced in the chemical combustion process are reincorporated into the wood biomass in the processes of photosynthesis. In this way, wood is regenerated in a natural process.
COMBUSTION (C6H10O5)n+6O2→ 6CO2 + nH2O (C6H10O5)n – cellulose
Photosynthesis is – as is commonly known – a chemical reaction that uses the “free” energy of solar radiation. The electromagnetic radiation of the sun is transformed into chemical bonds of the elements that make up biomass (mainly: C, H, O).
PHOTOSYNTHESIS 6CO2 + 6H2O→ C6H12O6 + 6O2
There is therefore no alternative fuel to biomass (including wood) that maintains the CO2 cycle in a closed cycle. Natural gas, coal and crude oil, burned in boilers and engines of cars, planes, ships, etc., emit carbon dioxide into the atmosphere, which is considered a so-called greenhouse gas. Carbon dioxide from the combustion of these fuels cannot be converted back into the chemical bonds of conventional fuels.
It is quite commonly believed – although opinions on this matter are divided – that the increase in the content of carbon dioxide emitted into the atmosphere is the cause of climate changes on Earth referred to as global warming. This ecological view, i.e. that the increase in the amount of carbon dioxide in the atmosphere causes climate changes that are undesirable for humans, should encourage the increasingly widespread use of wood for heating purposes. Unfortunately, this is not the case in Poland. There are no incentives to use wood for heating purposes (just as wood is supported as a heating fuel in many European countries), and even a ban on the use of wood is being introduced (as in Krakow, for example).
It is a kind of hypocrisy to simultaneously proclaim slogans about protecting the natural human environment – recommending the widespread use of renewable fuels (such as wood) – and at the same time prohibiting their use.
Wood can be stored for a long time, preserving it for burning at any time of the year. Forests, and currently also so-called energy plantations (willow, poplar, black locust) are a source of fuel that can cover the entire local demand for fuel for heating purposes. There are numerous examples of this in Austria, Switzerland, Italy, Germany and other countries in Europe.
Wood can be processed into a form of fuel that is adapted to the design of the stove, boiler or fireplace. This can be:
- Pieced wood
- Chips (pieces of wood chopped up to 2-3 cm long)
- Briquettes
- Pellets
- Charcoal
A form of wood biomass that is properly prepared for combustion enables the automation of feeding this fuel into the combustion chamber. Similarly to the operation of a gas, oil or coal boiler for so-called eco-pea coal, the operation of a wood biomass boiler by the user basically consists only of refilling the fuel in the tank (even every few days).
To sum up, the basic (though not the only) specific advantages of wood as an energy raw material are:
- closed CO2 circulation in the atmosphere, i.e. it is an ecological fuel
- possibility of long-term storage (warehousing)
- widespread availability of technology for processing wood (chipping, briquetting, pelleting) into a form that meets the construction and operational requirements of boilers.