Trying to make fuel from domestic waste

The common wisdom holds that where there's muck there's brass. A scientist originally from Athlone and now working for the EU's Joint Research Centre (JRC) in the Netherlands is busy trying to prove this is true.

A member of the JRC's clean energy unit and based at Petten, about 60km north of Amsterdam, Dr Chris Hunter is studying ways to get useable, cheap energy from waste of all kinds. It doesn't matter whether it is domestic refuse, waste coming from food processing or animal or vegetative waste from farms, or even biomass. All of it contains hydrogen and if you have hydrogen you have a useable fuel, says Hunter.

The EU today announces the opening of a new multi-million euro research centre built over the last four years at Petten dedicated to the study of hydrogen fuels. Petten is one of seven institutes within the JRC, the European Energy Institute.

The new purpose-built hydrogen facility has the equipment to study the hydrogen fuel storage tanks used in cars, buses and factories and the centre will also test fuel cell designs. These can be tested in conditions that simulate all types of weather from the Arctic to the Mediterranean.

Hunter's work at Petten is further back down the research line, where the hydrogen fuel is first produced. "We are part of the chain at the very beginning. You have to generate the hydrogen or take it from somewhere."

The scientist is originally from Athlone. He did a mechanical engineering degree at Trinity College Dublin and then did his PhD there, specialising in the performance of metal tubing under extreme conditions of temperature and pressure. In 1990 he moved abroad and has remained there in research since.

He is studying a range of hydrogen sources, derived from solid and liquid wastes and from biomass. "The goal is not to exclude any source of hydrogen. There are different ways to get the hydrogen but some are just not a runner," he says.

The two most promising methods involve either gasification of the waste through heating, or bioprocessing, the use of bacterial breakdown to produce fuel.

It doesn't matter whether it is purpose-grown biomass or domestic waste. "You can just burn it but there are other processes to create fuels," says Hunter.

Waste can be heated to drive off gases and provide fuel. "These will contain methane, dust and other materials. You can clean up the gases and get the dust out to end up with methane that can be burned directly or used to extract hydrogen."

Biological digestion also works but is also highly suited to liquid wastes including animal slurries and liquids from food and dairy processing. "This process can be used for biomass or slurry. You ferment the material and trap the gases that are coming off the process." The methane is retained and again either burned directly or used as a feedstock for hydrogen.

The bio route is far less demanding technically, he says. The thermal process runs at between 500 and 800 degrees while the biological breakdown happens at between 60 and 100 degrees.

"In principle both systems are viable," he says. "With the biological systems, you have waste anyway and you have to do something with it. The technology involved with biological is less complex. With the thermal processes hydrogen recovery is not widely used and not proven."

Ironically the idea of using solar cells to produce electricity that could then be used to split water into oxygen and hydrogen doesn't seem economically viable and may cause more harm to the environment than good , he says.

"The idea sounds fantastic but isn't economic. Theoretically this looks good and seems green." Production of the solar cells demands power and creates its own waste. Taking all this into account, it doesn't help the environment. "You use more energy creating the fuel than you will derive from burning the resultant fuel," he says.