Can renewable energy power the world?
Can renewable energy power the world?

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Can renewable energy power the world?

4.7.2 Land use

At some stage, all forms of biomass require a surface area of land or water for plant growth. Using this land for non-biological forms of renewable energy rather than for biomass might do more to mitigate the impacts of CO2 (Smith et al., 2000). How do the various land areas compare?

Assuming a biofuelled power plant with an annual electrical output of 10 GWh (the equivalent of a small 1.5 MW thermal power station running with a 75% capacity factor), with reasonable yields and conversion efficiencies the area of energy crops required to fuel this power plant would be in the range 600–900 ha (6–9 km2).

A small wind farm might need approximately 100 ha, (including necessary separation distances)

However, PV and wind systems are more likely to be complementary than to be competing for the same land, and as you saw in Week 3, PV arrays could be deployed to considerable advantage in semi-arid and desert areas with high solar input, or on rooftops in urban areas.

Nevertheless, there have been widespread concerns about the use of land for biofuels rather than for food, and about possible reductions in biological diversity through conversion of existing vegetation to fuel crops.

Activity 3

Are there any bioenergy systems you can think of that could allay the above concerns?

Answer

Some bioenergy systems, such as short rotation forestry or coppice, can increase biodiversity compared to conventional agriculture.

Bioenergy’s effects on soil also need to be considered. Soils can contain large amounts of organic matter or humus formed from the remains of crops that are hard to break down, and act as a store of large amounts of carbon over long periods. However, cultivating the soil exposes this organic material to the air, and it then begins to break down more rapidly, releasing carbon dioxide.

We’ll now move on to discuss bioenergy’s energy balance.

RENC_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has over 40 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus