Environment

There's a lot more to green technology than renewable energy. From more efficient aircraft to thread made from chicken feathers, the world is awash with ingenious ideas. So we have scoured research labs and start-ups, and made some hard choices. Here you will find our pick of the best ideas to make our planet a more energy-efficient place

Pee-n-grow

Manufacturing artificial fertiliser is a highly energy intensive process that consumes roughly 1 per cent of the world's energy supply. As odd as it sounds, using sterile, nitrogen-rich human urine instead could prevent the emission of more than 180 million tonnes of C0₂ each year. Urine collection systems with basement storage tanks have been built by the Stockholm Environmental Institute in more than 800 apartments in rural China, saving an estimated 20 tonnes of C0₂ emissions annually.

China: available now

Magnetic fridge

The two biggest consumers of electricity in the home - air conditioners and refrigerators - may soon become much more energy efficient thanks to a new method of cooling. Magnetic refrigeration subjects metal alloys to a magnetic field, causing them to cool down. Camfridge, based in Cambridge, UK, says its fridges and air conditioners will cut energy usage by around 40 per cent in comparison with conventional models.

Cambridge, UK: under development

Green machine

The world's first "virtually waterless" washing machine could soon slash the water and energy demands of dirty laundry. Prototypes developed by UK start-up Xeros rely on thousands of polarised nylon beads. These stick to dirt and gobble up stains, leaving clothes dry, and using 90 per cent less water and 40 per cent less energy than conventional washers and driers combined. If the estimated 300 million households worldwide with existing washers switched to these machines, annual C0₂ emissions would drop by 28 million tonnes.

Leeds, UK: available 2010

Better windows

Increase the number of layers of glass or plastic in a window and you'll save big on heating and cooling. Visionwall of Edmonton in Alberta, Canada, makes a quadruple-glazed window consisting of two layers of rigid polyethylene sandwiched between two glass layers which cuts heat loss by a factor of 4 compared with conventional double-glazed windows.

Edmonton, Canada: available now

The power of pond scum

Green algae grow like mad when fed CO₂, and if turned into biofuel can yield up to 100 times the biofuel per hectare as corn, soy or sugar cane crops. Petroalgae of Melbourne, Florida, plans to license their first 2000-hectare commercial alga biodiesel plant in China next year and says the green stuff can ingest C0₂ straight from the smokestacks of power plants. If emissions from all the world's power plants were harnessed for alga growing and recycled as biodiesel, C0₂ emissions would drop by roughly 9 billion tonnes per year.

Melbourne, Florida, US: available 2010

Methane harvesting

Methane extracted from animal waste can be used as a fuel. The world's largest biogas plant in Penkun, Germany, was completed in 2008 and converts 84,000 tonnes of manure a year into usable fuel. The liquid manure, along with maize and grain, is fed into fermenters where the biomethane generates 20 megawatts of electricity and 22 megawatts of heat for the town's 50,000 inhabitants.

Penkun, Germany: available now

Superconducting grid

Up to 10 per cent of all electricity produced is lost before it even reaches the intended user due to inefficiencies in the grid. American Superconductor based in Devens, Massachusetts, has developed a superconducting wire that cuts transmission line losses threefold when chilled to -196 ° C. In 2008, the company supplied the wire for the world's first superconducting transmission line, a 600-metre, 574-megawatt cable in New York state.

US: available now

Giant microwave ovens

Known for their ability to warm food using little energy, microwaves could soon save the chemicals industry massive amounts of electricity by heating chemical reagents in much the same way. Each year, chemical manufacturers in the UK alone consume the equivalent of the electricity produced by 20 coal-fired power plants. Recent tests suggest that microwaves can cut energy requirements for heating in chemical production by as much as 90 per cent.

UK: under development

Pleasant light

Light-emitting diodes can produce the same light as incandescent or even compact fluorescent lighting for only a tiny fraction of the energy. However, the light they produce is pale and cool, which means people are reluctant to use them. UK-based company Oxford Advanced Surfaces has the answer. It is developing phosphorescent screens that convert blue-tinged LED light into the warm white light we are used to from conventional bulbs. Worldwide adoption of LEDs could cut global energy consumption for lighting in half, the company says.

UK: under development

Waggling wings

Modern passenger planes are masterfully streamlined but the aircraft are still burdened by turbulence that forms as a result of friction between the plane's skin and the air that passes over it. Wind tunnel tests now show that if only a small part of an aircraft's wings were made to oscillate from side to side, the resulting decrease in drag would reduce fuel consumption by 20 per cent.

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