Energy crops grown for biomass

Overview

Short rotation willow and poplar coppice, Miscanthus, maize and sugar cane, Brazil's bioethanol, bioethanol and biodiesel, the food versus fuel debate, and a Miscanthus energy yield calculation.

What you need to know

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Questions from this subtopic

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1. 1

   Name five crops grown commercially to produce biomass.

   Model answer

   Sugar cane, maize, willow, poplar and elephant grass are all grown commercially for biomass.

2. 2

   What is short rotation coppice?

   Model answer

   Short rotation coppice is a woody crop, such as willow or poplar, cut back to ground level every two to four years. New shoots regrow from the stumps, so the plantation lasts twenty years or more.

3. 3

   Why is willow well suited to growing as a biomass crop in Northern Ireland?

   Model answer

   Willow grows quickly in cool, wet conditions and tolerates heavy, waterlogged soils. Land unsuitable for other crops can therefore produce fuel.

4. 4

   How is a willow coppice crop harvested and used?

   Model answer

   Specialist harvesters cut the stems in winter and chop them into chips in one pass. The chips are dried and burned in boilers or power stations.

5. 5

   How does poplar compare with willow as a biomass crop?

   Model answer

   Poplar is also fast-growing and can be coppiced, but it is often grown as short rotation forestry with single stems. Poplar is less tolerant of waterlogged ground than willow.

6. 6

   What is elephant grass?

   Model answer

   Elephant grass, or Miscanthus, is a tall perennial grass from Asia grown for biomass. The crop grows over 3 m tall each year from underground rhizomes.

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