Natural gas tens of millions of structures that use the fuel, the individual risk of using natural gas is very low. Natural gas heating systems may cause carbon monoxide poisoning if unvented or poorly vented. In 2011, natural gas furnaces, space heaters, water heaters and stoves were blamed for 11 carbon monoxide deaths in the US. Another 22 deaths were attributed to appliances running on liquified petroleum gas, and 17 deaths on gas of unspecified type. Improvements in natural gas furnace designs have greatly reduced CO poisoning concerns. Detectors are also available that warn of carbon monoxide and/or explosive gas (methane, propane,
Substitute natural gas condition for large scale introduction of renewable biomethane produced through anaerobic digestion (biogas) or gasification and methanation bio-SNG. Substitute natural gas Substitute natural gas (SNG), or synthetic natural gas, is a fuel gas that can be produced from fossil fuels such as lignite coal, oil shale, or from biofuels (when it is named bio-SNG) or from renewable electrical energy. The Great Plains Synfuels Plant injects approximately 4.1 million m/day of SNG from lignite coal into the United States national gas grid. The production process of SNG at the Great Plains plant involves gasification, gas cleaning, shift, and methanation. China is