Cars that run on a by-product of human sewage could replace petrol vehicles within a span of three years, according to a report.
A car manufacturer in Japan is backing a consortium which is investigating a process that turns sewage sludge into hydrogen for use in fuel-cell vehicles.
Fuel-cell vehicles are seen by many as a better zero-emissions alternative to plug-in electric vehicles because they offer greater range and don't rely on electricity grids that are often powered by coal, according to Japan's 'Nikkei business daily'.
Instead they use an on-board chemical reaction between hydrogen and oxygen to produce electricity. The by-product that comes out of the exhaust pipe is water.
However, one of the main obstacles to commercialise the fuel-cell vehicles is the process of producing hydrogen.
The traditional method, which is expensive and complicated, involves extracting it from liquefied natural gas or fossil fuels.
The consortium has said that extracting hydrogen from sewage is cheaper and more environmentally friendly than traditional methods. It claims the process cuts carbon emissions by 75 per cent, 'Stuff.co.nz' reported.
The process involves drying out the sludge to generate methane gas. The methane gas is then reheated to extract a high concentration of hydrogen gas.
The consortium is aiming to commercialise the process by 2015.
A number of car makers, including Toyota, Honda, Hyundai, Nissan and Mercedes-Benz, are working on fuel-cell vehicles, although significant hurdles, including refuelling infrastructure, remain.