One renewable energy source is easily available as waste from from construction, agriculture, landscaping, logging and sawmills. And it's already used in domestic and district-level heating systems.

It is the main solid biomass fuel source used for combined heat and power production, known as co-generation, a definite advantage as an energy source.

It's wood chips, but you don't hear much about them.

“Woodchips have an important value, first of all, to stimulate the care of a resource like the forest that has often been abandoned”, Stefano Dal Savio, an environmental engineer and manager of the energy and environment area of TIS Innovation Park in Bolzano, Italy told  “[They also] enable the production of a local and renewable fuel.”  

Used as a power source, woodchips could help nations ensure that a part of their energy production comes from within the country, promoting the use of a forestry technique based on two to four year wood cutting cycles, called short rotation coppice (SRC), to produce woodchips for district heating systems in Eastern Europe.

 “If you produce only heat from woodchips you have an energy efficiency of more than 80%, in cogeneration plants the efficiency is 65 % whereas in power-only production plants [it is down to] 30-40%,” Edita Vagonyte, European Affairs Manager from the Brussels, Belgium-based European Biomass Association, said. “Since many power plants in Europe produce electricity only, the aim at EU level is to build only new cogeneration plants so that the efficiency is increased and we use the biomass more efficiently.”

In particular, trigeneration systems, which generate a combination of cooling, heating and power, are the best possible option. When it comes to energy production, woodchips offer an alternative to other energy sources. “From one hectare of land planted with poplar between 15 and 30 tons per hectare per year of biomass can be obtained. The shorter the duration of the cycle, the greater the amount of biomass [obtained], even though of lower quality since it will have a higher quantity of bark.” 

He estimates that at an average value of 22 tons per hectare per year the amount of energy produced by woodchips would be of 77000 kiloWatt hours per year. This is equivalent to 45 oil barrels or to 23 photovoltaic roof systems each producing 1.8kw from solar power.

Woodchips are not as attractive in terms of carbon emissions as renewable energies like photovoltaic solar energy, though its combustion is CO2 neutral as long as no more trees are cut than those that are replanted and planting, farming, harvesting, chipping and transportation do cause net emissions. Transport would be where most of the CO2 is emitted.

For woodchips to be a sustainable energy source, the transportation distance from the plantation to the power and heating plant would need to be limited to between 40 to 70 kilometers. Vagonyte remarks: “Woodchips contain around 50% of water; therefore, it is not even economically viable to transport them over long distances.”