Like many of its European neighbours, Germany wants to reduce its dependency on natural gas from Russia. An interesting new study from the Technical University of Hamburg (TUHH) proposes that biomethane synthesised from organic kitchen waste could supply a chunk of the country’s gas demands.

"A large part of the kitchen waste mistakenly ends up in the residual waste, is thus incinerated and lost for high-quality energy and material recycling," says Ina Körner, from the Institute for Wastewater Management and Water Protection at TUHH in an article in SolarServer.

An average person generates around 85 kg of organic kitchen waste a but only c. 21 kg of it is collected in waste caddies for turning into compost or biogas. However, if the full kitchen waste potential of Germany’s 83 million inhabitants was tapped, the team estimates that the average gas consumption of 2.8 million people could be covered for a whole year.

The science behind it is not complicated: "Biogas mainly contains methane and CO2," Professor Körner explains. "By removing the CO2, you can produce biomethane, which has a similar calorific value to fossil natural gas. Only about 15 percent of Germany's 115 municipal biogas plants operate according to this principle and feed biomethane into the natural gas grid. So there is still room for improvement."

In addition, other municipal bio-residues could be used including green waste from foliage, sewage sludge and agricultural manure. The first step is for local governments to recognise the value of this waste. "The more waste is collected, the greater the incentive to build new composting and biogas plants and to upgrade existing ones for biomethane production." In Hamburg, for example, only 60 percent of households have access to the organic waste bin but Körner recommends a target of at least 65 percent of kitchen waste collection per city.