Sustainable energy that hits back

Technologies are being developed which promise to combat climate change and generate energy from unexpected sources. Jim McClelland looks at five of the most promising


01 BIOFUELS FROM ALGAE

A near-perfect poster child for sustainable energy, algae is both a biodegradable living organism and literally green. It can be grown on land unsuited to traditional agriculture and it uses hardly any freshwater resources.

Research and development funding for farming (algaculture) has flowed into institutions around the world, including the US National Renewable Energy Laboratory (NREL) and the EnAlgae project, a strategic initiative supported by the INTERREG IVB North-West Europe programme.

The world’s first algae-powered demonstration building has also been built in Germany, featuring bio-reactive louvers. Yet, while promise and expectation run high, commercialisation is still work in progress. ExxonMobil has already invested $600 million in developing motor fuels from algae with human-genome scientist J. Craig Venter, but chief executive Rex Tillerson acknowledges that development success was probably further than 25 years away.

Laura Stowe, of EnAlgae, concurs, saying: “Algae has great potential, not only as a source of bioenergy, but also for products including pharmaceuticals, food and cosmetics. However, more research and development is needed to create a viable marketplace.”

02 PETROL FROM AIR

Generating energy from nothing more than air would seem to be another utopian vision. However, several successful, related initiatives have already been brought to market. These include air-source heat pumps for domestic installation and compression technologies, such as that deployed in a forthcoming car from PSA Peugeot Citroën, the Hybrid Air, which will be in production in 2016.

At an industrial scale, there are opportunities for “closed-loop” generation where industrial facilities, such as distilleries which produce “waste” CO2, use the gas as a feedstock to produce other products. Darlington-based Air Fuel Synthesis (AFS) produces liquid fuels from the greenhouse gas.

The AFS system uses renewable energy to capture CO2 and water from the air, electrolyses the water to make hydrogen, and reacts the carbon dioxide and hydrogen together to make hydrocarbon fuels.

While very different in origin from traditional fossil-fuel products, the resultant “petrol from air” is perfectly compatible in use, performing like standard 95-octane fuel. It is a renewable hydrocarbon and, therefore, can be blended in any proportion with normal petrol, easily stored, transported and used in existing vehicles.

03 ENERGY FROM CHANGE

Phase Change Materials (PCMs) are capable of transforming from solid to liquid and vice versa, which allows them to absorb or release large amounts of latent heat at relatively constant temperatures. While PCMs have been around for more than 50 years, only in the last decade have they been micro-encapsulated and incorporated into building products, such as commercial ceiling tiles and wall panels.

On installation, total energy demand for mechanical heating and cooling from existing heating, ventilation and air-conditioning (HVAC) systems can be reduced by up to 60 per cent. PCMs are compatible with renewable generation and can help to flatten both high and low-temperature energy-usage peaks.

Mike Berry, managing director of UK producer, Datum Phase Change, explains: “We are working on solar-thermal systems which require zero energy and provide dual benefits. They utilise hot water through a radiant ceiling system for free heating during winter months and also deliver radiant cooling during summer periods.”

Growing mainstream interest in PCMs is evidenced by the recent investment in Datum Phase Change made by Sir Terry Leahy, former chief executive of Tesco.

04 POWER FROM PEOPLE

Kinetic energy, produced by acts of motion, has seen numerous applications in road and rail transport, powering street lights and monitoring systems via energy from cars passing over ramps and from track vibrations or regenerative braking systems on trains.

Through human footfall, it has also recently been generating excitement of Olympic proportions. For the London 2012 Games, energy-harvesting floor tiles were installed along the temporary walkway from West Ham Station to the Olympic Park, providing people-powered illumination around the clock, thanks to millions of spectator footsteps.

The tiles, manufactured by Pavegen Systems, have also been used by Japanese retailer Uniqlo in a campaign to raise awareness of an innovative clothing range. For Uniqlo, “Heat Spot” games in UK shopping areas generated thousands of joules of renewable energy and Facebook “likes”.

The importance of human engagement is emphasised by Mark Randall, founder and chief executive of Renaissance Capital Partners, who installed Pavegen at his company’s headquarters: “Our experience is that this footfall-harvesting technology really engages staff and clients with issues of sustainability.”

05 FUTURES FROM WASTE

Public engagement of another kind is driving the market for advances in waste-to-energy solutions, as local opposition to incineration projects and their emissions opens the door to alternatives.

Key solutions are pyrolysis and plasma gasification, both thermal processes employing high temperatures to break down waste, without the need to burn it. They produce synthesis gas, or “syngas”, which is mostly hydrogen and can be used to generate electricity either via a turbine or by using hydrogen fuel-cell technology.

John Hall, managing director of Waste2Tricity, is working with Alkali Power & Energy on the significant next phase in development. He says: “The latest concept is to link alkaline fuel cells to the process, using hydrogen from syngas to increase electrical output by over 40 per cent compared to traditional internal combustion.”

The world’s largest energy-from-waste plant, capable of powering 50,000 homes, is currently being built on Teesside. Rather than being seen only as part of the problem of our resource-consuming past, waste is now fast being recast as part of the solution for our energy-generating future.