Biogas can be used in cars primarily by upgrading it to Renewable Natural Gas (RNG), which is chemically equivalent to fossil-fuel-sourced compressed natural gas (CNG). This biomethane can then be used to fuel vehicles equipped with CNG engines. The process involves purifying raw biogas—which is produced from the anaerobic digestion of organic waste like landfills, agricultural manure, and food scraps—by removing impurities like carbon dioxide and hydrogen sulfide. The resulting RNG is a drop-in fuel for the existing natural gas vehicle infrastructure, offering a significant reduction in lifecycle greenhouse gas emissions compared to gasoline or diesel.
The technology is proven and in use today. Many municipal bus fleets, commercial trucks, and even personal vehicles are already running on RNG. The primary advantage is its status as a carbon-neutral or even carbon-negative fuel. Because the carbon in RNG comes from organic matter that recently absorbed CO2 from the atmosphere, burning it simply returns that carbon, creating a closed loop. This is in stark contrast to fossil fuels, which release ancient carbon stored underground.
| Aspect | Data Point | Source / Context |
|---|
| Methane Content (Upgraded RNG) | > 95% | Must meet pipeline-quality standards ( > = 97% methane in the U.S.) |
| Reduction in GHG Emissions | Up to 300% lower than diesel | Argonne National Laboratory's GREET model (accounts for avoided methane emissions from waste) |
| Number of CNG Stations in U.S. | ~1,300 public & private stations | U.S. Department of Energy, Alternative Fuels Data Center (2023 data) |
| Cost Comparison to Diesel | Typically 20-40% lower per gallon equivalent | Highly dependent on regional RNG incentives and production |
| Vehicle Availability | ~175,000 NG vehicles in U.S. | Includes buses, trash trucks, and commercial vehicles (2022 data) |
| Energy Content (GGE) | 1 GGE = 126.67 cubic feet of CNG | Gasoline Gallon Equivalent (GGE) standard for comparison |
The main hurdles are infrastructure and vehicle cost. While the refueling network is growing, it's not as ubiquitous as gasoline stations. Purchasing a new CNG vehicle often comes with a higher upfront cost than a comparable gasoline model, though fuel savings can offset this over time. For most individual consumers, adopting biogas as a vehicle fuel currently means choosing a CNG model like the Honda Civic Natural Gas (discontinued but available used) or models from manufacturers like Ford that offer CNG-prep packages for fleet vehicles. The real growth is in the commercial and public transport sectors, where the environmental and economic benefits are most pronounced.
