Renewable Energy

In the UK and Germany there is a lot of buzz around producing biomass ie. renewable energy. The whole purpose of producing biomass is of course to create a sustainable source of energy. With short term crop rotations, that is certainly viable for some tree species.

Things to consider are:

1. Which tree species to grow
2. How many trees to plant per hectare
3. What yield each species will produce in dry tonnage per hectare per year
4. Yields and other costs that come with such an activity, like transport and harvesting

Which trees to grow?

There are basicaly 3 species that are used to produce biomass: Robinia, Willow and Poplar. Of these, Poplar seems to be the best suited, as it grows the fastest. It does however, need a lot of water, which is not always at hand in eastern Germany. Robinia doesn't need a lot of water, but on the other hand, produces the least amount of biomass per hectare of these 3 species.

Example: Willow: 10 tons per hectare/ year. Poplar: 12-15 tons per hectare/ year. Robinia: 7-8 tons per hectare/ year.

How many trees to plant?

Opinions vary, but on average at least 10,000 trees should be planted per hectare. Which make the start up costs quite considerable.

Yield and other costs:

Current price (in Germany) is about 90 Euro per ton. But from that, costs for harvesting and transport are deducted, leaving only a net price of about 60 Euro per ton. Especially the transport costs are fundemental, the plantations have to be in proximity of an electricity plant in order to keep those costs down. You can only transport 25 tons of biomass (or any other timber) per truck. 100 kilometres is the maximum range for this. Beyond that and the transportation costs eat up all the profits.

Land prices have also to be considered. They have to be low, or otherwise it takes decades to turn a profit with biomass.

Wouter Bakker