Biogas made from byproducts is the vehicle fuel that offers the most environmental benefit. That’s the conclusion of research done by the Faculty of Engineering at Lund University, Sweden.
“In the worst case the climate effect is reduced by 60 percent compared with diesel and petrol fuels,” says researcher Pål Börjesson.
The results of the study were presented at a conference at the Elmia Recycling trade fair in Jönköping, Sweden. The faculty’s Division of Environmental and Energy Systems did the theoretical calculations and also studied an existing biogas production facility in Sweden: Wrams Gunnarstorp.
“We calculate that as it is run today, this production facility reduces the total emissions of climate-impacting gases by 95 percent compared with vehicles that run on diesel or petrol,” Börjesson says.
The benefits of biogas are not entirely uncontroversial. The storage and anaerobic digestion processes release methane into the atmosphere, which is a far more potent greenhouse gas compared with carbon dioxide. The production facility also uses up energy and the byproducts are transported by fossil-fuel-driven trucks.
“The leakage of methane gas is currently 1 to 1.5 percent and it would have to be 14 percent before the environmental impact would be as great as if the same vehicles that run on biogas today were to run on fossil fuels,” he says.
Chips instead of gas
Börjesson says there is a lot of room for improvement. One way would be to stop operating a biogas production facility on its own biogas. It is better to use wood chips and sell all the biogas produced as a vehicle fuel. This is because the environmental benefits of running vehicles on biogas are many times greater than those achieved by using biogas to power a production facility.
Another debated issue is how great the potential is for biogas. According to E.ON Gas, which is Sweden’s biggest producer and distributor of vehicle gas, there are enough waste and byproducts so that in ten years from now, ten percent of all cars, trucks and buses could run on biogas.
“But we still have a lot to do before we get that far,” says Mattias Hennius of E.ON Gas.
Ten percent of Swedish vehicle fuel equates to the fuel used by 250,000 cars, 6,000 buses and 14,000 trucks. To convert all those vehicles to biogas doesn’t just require resources – even more important is the availability issue.
“In Sweden today there are only 105 stations selling vehicle gas and many of them are located alongside sewage works and similar facilities,” Hennius says. “That’s why we’ve begun cooperating with the OKQ8 petrol company to set up vehicle gas pumps along the major arterial roads, together with all the service that car drivers expect.”
But are there really enough raw materials to produce all this biogas? Both the researchers and E.ON say yes. The raw materials are available and are, in decreasing percentages: manure, industrial waste, food waste, sewage sludge and harvest byproducts.