FEATURE-Britain starts digesting as biogas catches on
LONDON, July 30 (Reuters) - Medieval alchemists tried in vain to find a way to turn lead into gold, but modern technology is rediscovering a more ancient transmutation -- turning trash and sewage into energy.
Biogas -- created from waste, sewage, manure, grass and even pig remains has become an increasingly popular source of environmentally friendly energy in Europe and Asia.
Another name for methane, biogas as a source of electricity cuts mankind's contribution to global warming by burning this potent greenhouse gas, otherwise released into the atmosphere.
"It makes us self-sufficient in power and it is low carbon and makes use of waste resources... It's purely driven by the green agenda," said farmer Owen Yeatman, a public promoter of biogas systems at his Dorset, southwest England farm.
Fed maize from his farm, the 750,000 pounds ($1.51 million) system will produce enough gas both to maintain it and heat around 450 houses.
Germany leads the world with around 70 percent of the global market and produced 1,100 megawatts of electricity from biogas last year, enough to supply over a million homes, said German biogas plant developers Biogas Nord.
Britain, which wants to raise its share of renewable energy, only produced around one-25th of this, according to Germany's Agency of Renewable Resources.
Like liquid biofuels -- used to power cars -- biogas involves generating energy from organic matter. It has the same structure as natural gas and is transported the same way.
MARCO POLO
Biogas is not new. There is anecdotal evidence it was used for heating bath water in Assyria during the 10th century BC and in Persia during the 16th century AD, according to the University of Adelaide's Web site 'A Brief History of Biogas'.
It captured the attention of 13th-century adventurer Marco Polo in China, where he noted covered pots of sewage stored to generate energy -- and earned a mention by 17th-century writer Daniel Defoe.
Now environmentalists hail biogas on two counts: it prevents methane created by decaying organic matter from entering the atmosphere in its pure form, and is renewable.
It is generated in two main ways: by putting organic waste in sealed containers, or by capturing gas emitted by landfill waste dumps.
Million-dollar complexes that have canisters acting as mammoth compost bins produce most of Europe's biogas, through the process known as anaerobic digestion.
But almost all Britain's biogas comes from landfills, and is often converted into electricity.
"We are now capturing the majority of gas that landfills produce," said Michael Walker, Policy Director of the Environmental Services Association (ESA), which represents the British waste management industry.
Landfill gas makes up a quarter of British renewable energy, the ESA said, giving electricity to some 900,000 households. The rest comes from wind, solar, water, geothermal and a tiny share from anaerobic digestion.
BIOGAS BUSES
Britain's low position on the biogas ladder is not surprising -- the crowded island only recycles around 15 percent of its household waste. That's far less than most European countries like top recycler the Netherlands at around 60 percent.
But Britain is being forced to go the renewable route. The European Union set a target of increasing renewable energies to 20 percent by 2020 in last year's Energy Review.
It now stands at 2 percent in Britain, the country's Renewable Energy Association (REA) says. The EU as a whole sources 6.5 percent of its energy from renewables, with Latvia the highest at 47 percent, the EU says.
Germany builds around 1,000 digesters a year, Yeatman said, and Scandinavian countries and Austria, Canada and Australia are also devotees of the system.
Though biogas makes up a tiny proportion of renewables, some countries are surging ahead with it -- many public buses in the Stockholm region run on biogas, the EU says.
"If we go further down the carbon-saving route -- which is the government's avowed intention -- there is no doubt that the carbon saving is very impressive," said REA's Head of Biofuels Clare Wenner.