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

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Can renewable energy sources power the world?

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 bio-fuelled 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 Bioenergy systems

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. Among more experimental technologies, microalgæ don’t take up agricultural land and may be useful in cleaning up both nutrient residues and carbon dioxide, while secondary biofuels, using agricultural residues that would otherwise be burned or ploughed back in, offer another low impact option. More research is needed into these technologies.

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.

RENBOC_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 50 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, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 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 prospectus371