Compressed natural gas garbage trucks and its uses

Compressed natural gas garbage trucks

Compressed natural gas (CNG) is a fuel gas consisting primarily of methane (CH4) compressed to less than 1% of its volume at standard atmospheric pressure.It is stored and dispensed in rigid containers at a pressure of 20-25 MPa (2,900-3,600 psi),usually in cylindrical or spherical shapes.CNG is used in conventional gasoline/internal combustion engine vehicles that have been modified,or vehicles built specifically for CNG use:alone (dedicated),using an isolated liquid fuel system for extended range (dual fuel),or in combination with other fuels (dual fuel ).It can be used instead of gasoline (petrol),diesel and liquefied petroleum gas (LPG).CNG combustion produces fewer harmful gases than the aforementioned fuels.Natural gas poses less of a threat in the event of a spill than other fuels because it is lighter than air and dissipates quickly when released.Biomethane-refined biogas from anaerobic digestion or landfills - can be used.In response to high oil prices and environmental concerns,CNG has been used in motorized rickshaws,pickup trucks,buses and school buses, and trains.The cost and placement of fuel storage vessels is a major barrier to wider/faster adoption of CNG as a fuel.This is also why municipalities,public transport,are the most obvious early adopters,as they can more quickly amortize the money invested in new (often cheaper) fuels.Despite these circumstances,the number of vehicles in the world using CNG is growing steadily (30% per year).Now,due to the steady growth of the industry,the cost of such fuel storage cylinders has come down to a more acceptable level.In particular,for CNG Type 1 and Type 2 cylinders,many countries are able to manufacture reliable and cost-effective cylinders to meet conversion needs.

Uses 

Motor vehicle

By 2011, there were 14.8 million natural gas vehicles (NGVs) globally,with Iran (4.07 million),Pakistan (2.85 million),Argentina (2.07 million),Brazil (1.7 million) and India (1.1 million vehicles),the Asia-Pacific region leads with 5.7 million NGVs,followed by Latin America with nearly 4 million vehicles.Dual fuel vehicles are sold by various car and vehicle manufacturers like Fiat,Opel/GM,Peugeot,Volkswagen,Toyota,Honda,Maruti Suzuki,Hyundai,Tata Motors,etc.In 2006,the Fiat Siena Tetrafuel was introduced to the Brazilian market with a 1.4 liter FIRE engine running on E100, E25 (Brazilian standard gasoline),ethanol and compressed natural gas.Any existing gasoline vehicle can be converted to a dual-fuel gasoline/CNG vehicle.Authorized shops can perform modifications, including installation of CNG cylinders, piping,CNG injection systems and electronics.The cost of installing a CNG conversion kit on passenger cars and light trucks can typically run up to $8,000 and is usually reserved for vehicles that drive a few miles per year.CNG costs approximately 50% less than gasoline and emits 90% less than gasoline.

Locomotives

CNG locomotives are operated by several railways.The Napa Valley Wine Train successfully converted its diesel locomotives to run on compressed natural gas until 2002.This modified locomotive was upgraded to use a computer-controlled fuel injection system in May 2008 and is now the main locomotive for the Napa Valley Wine Train.Ferrocarril Central Andino in Peru has been operating CNG locomotives on freight lines since 2005.CNG locomotives are typically diesel-electric locomotives that have been converted to use compressed natural gas generators instead of diesel generators to generate the electricity that drives the traction motors.Some CNG locomotives are able to selectively fire cylinders only when power is needed,which in theory makes them more fuel efficient than traditional diesel engines.CNG is also cheaper than gasoline or diesel fuel.

Advantages

• Natural gas vehicles are less expensive to maintain than other hydrocarbon fueled vehicles.

• The CNG fuel system is sealed to prevent fuel loss through spillage or evaporation.

• Extends oil life because compressed natural gas does not contaminate and dilute crankcase oil.

• As a gaseous fuel,CNG mixes easily and uniformly in the air.

• CNG is unlikely to ignite on hot surfaces due to its high auto-ignition temperature (540 °C) and narrow range (5–15%) flammability.

• CNG powered vehicles are considered safer than gasoline powered vehicles.

•  Reduce pollution and increase efficiency:

• CNG directly emits significantly fewer pollutants when combusted than gasoline or petroleum (e.g.,unburned hydrocarbons (UHC),carbon monoxide (CO),nitrogen oxides (NOX),sulfur oxides (SOx),and PM ( particulates)). For example,an engine running 100 km on petrol produces 22 kg of CO2, while driving the same distance on CNG emits only 16.3 kg of CO2.

• CARB (California Air Resources Board) gives lifecycle greenhouse gas emissions of CNG compressed from California pipeline natural gas at 67.70 grams of carbon dioxide equivalent per megajoule (gCO2e/MJ), about 28% lower than regular gasoline fuels in this market (95.86 gCO2e/MJ).

• CARB found that CNG produced from landfill biogas had the lowest GHG emissions of any fuel analyzed,with a value of 11.26 gCO2e/MJ in the Low Carbon Fuel Standard entering 2018 (more than 88% lower than conventional gasoline ) entered into force on January 12, 2010.

• Switching to compressed natural gas helps reduce greenhouse gas emissions due to lower CO2 emissions.However, natural gas leaks (both for direct use and for the production and distribution of the fuel) imply increased greenhouse gas emissions.The ability of CNG to reduce greenhouse gas emissions throughout the fuel lifecycle will depend on the source of the natural gas and the fuel it replaces.