Biogas is 97% methane, the rest is made up by carbon dioxide and air. Methane is mainly produced by the purification of natural gas, but also biologically, by the bacterial degradation of waste. The gas is then called “biogas”.
Typical waste materials used for the production of biofuel are:
- Sludge from biological waste water plants
- Municipal waste material from households
- Agricultural waste material from piggeries, chicken yards, etc.
Uncleaned biogas has long been used for heating purposes locally. As traffic fuels need to be dry, clean and odorless, raw biogas is cleaned and also liquefied for storage.
The amount of biogas in a standard biogas-fueled car will give you around 200-400 km of mileage; most cars are designed to use both biogas and normal gasoline. Gas cars have proven to be as safe as standard cars; the gas tank is installed in the safest possible way and standard tests have shown that biogas installation cause no extra risks.
Biogas is 45% lighter than air and will rapidly rise and mix with ambient air. Its energy content is close to that of gasoline:
- 1 m³ biogas = 9.8 kWh
- 1 liter of gasoline = 8.8 kWh
Ignition temperatures in air
- Biogas 540 oC
- Gasoline 228 oC
- Diesel 260 oC
Biogas, traffic-fuel grade
- 97% methane, rest made up by carbon dioxide and air
- Relative density (air = 1) 0.555
- Flammability limits in air at 20 oC: 5-15%
