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.

4.3 Other energy crops

Starchy and sugary crops

The major biomass energy component of these crops, examples of which are shown in Figure 7, is their sugar or starch, which can be fermented to produce ethanol. Their supporting cellulosic tissues may also be used in the same way as the mainly cellulose crops. Globally, the most important crops for bioenergy purposes are sugar cane and maize.

Starch/sugar crops: (a) sugar cane, (b) maize harvesting, (c) sugar beet
Figure 7 Starch/sugar crops: (a) sugar cane, (b) maize harvesting, (c) sugar beet

Another sugar-rich crop of interest in Europe is sugar beet, where the roots contain 15–20% sugar. Sugar-cane bagasse (the sugar cane’s fibrous residue) and the straw from maize and other cereals can also be used for energy, in the same way as for cellulosic crops.

Oilseed crops

Sunflowers, oilseed rape and soya beans are grown widely for the oil in their seeds, while in tropical areas, oil palm (Elaeis guineensis) is a major crop.

The oils from these crops can be converted to a diesel substitute known as biodiesel. As with the starchy/sugar crops considered above, there is a residue left from these processes that is currently often used as animal feed, but which could be a bioenergy feedstock.

The oil from all these crops has a vast number of uses, for example in foods and cosmetics/ However, there are widespread misgivings about the conversion of mature forests to palm oil plantations in South-East Asia and elsewhere. The use of palm oil for bioenergy could lead to an increase in such problems.

Some types of algae can also be used to produce energy, as they too photosynthesise. You’ll look at this in the next section.

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