快猫短视频

What鈥檚 your approach to energy generation?
I am using anaerobic digestion 鈥� the breakdown of organic material in the absence of oxygen 鈥� to turn plant biomass into gas for generating electricity.

Aren鈥檛 biofuels discredited, partly because their production displaces food crops?
That鈥檚 why we need plants that grow fast in areas where food crops don鈥檛 grow. The solution is a largely overlooked category of plants that includes cacti such as prickly pear and other succulents (). They grow in semi-arid places too dry for rain-fed food crops.

What鈥檚 the succulents鈥� secret?
They produce a lot of biomass for very little water. Conventional plants lose loads of water to evaporation when they open their leaf stomata during the day to capture carbon dioxide for photosynthesis. These plants 鈥� known as CAM plants 鈥� get round that by capturing CO₂ in the cool of night and storing it for photosynthesis when the sun comes up. Some use only a tenth of the water to produce the same amount of biomass. My team at the University of Oxford is trialling plantations of prickly pear and Euphorbia tirucalli in Kenya. So far the yields look promising.

How much land is suited to these plants?
Worldwide, we think there are perhaps 300 million hectares of semi-arid land available in places where there is little other use for it. That鈥檚 an area the size of India. After being fermented to produce biogas, CAM plants could in theory generate as much electricity as is currently produced globally from burning natural gas.

How long until this technology is available?
CAM plants are already viable for biogas production, but they are at the same stage of plant-breeding development as food crops were 8000 years ago. I am sure yields can be improved a lot. But the biggest problem is that anaerobic digestion is slow and relatively expensive. The rumens of cows do the same thing up to 30 times as fast. If we could copy that, we could slash costs.

Surely the land you are targeting isn鈥檛 empty.
There鈥檚 little completely unused land, but lots of relatively unproductive land. East Africa, the Sahel and nations around the Mediterranean contain some of these areas. CAM plants could transform these places. They collect energy, water and nutrients. Anaerobic digestion releases this nutrient-rich water as a by-product 鈥� hugely valuable in semi-arid places. We鈥檙e looking at using this water to grow Lemna, tiny floating plants that produce lots of protein, which can be fed to fish or livestock. We ought to be able to produce energy, protein and water all from the same land.

What does this mean for the climate?
I鈥檓 ambitious. My aim is billion-tonne emission-reduction projects, to keep serious amounts of carbon out of the atmosphere. The emissions from creating all this energy will be low. It could have a real effect on curbing climate change.

This article appeared in print under the headline 鈥淧rickly pears to the rescue鈥�