Keywords: compressed natural gas vehicle; Gas filling station; Development prospect; Countermeasures
At present, automobile exhaust emission in some big cities in China is the main source of urban air pollution. Therefore, the development of clean energy vehicles has become an urgent choice. Compressed natural gas (CNG) vehicles are welcomed by all countries because of their low energy consumption and low pollutant emissions, and are internationally recognized as the most ideal alternative energy sources for vehicles. Developing natural gas vehicles is of great significance for solving environmental and energy problems.
First, the development of natural gas vehicles
L, the development of foreign natural gas vehicles
In order to protect the environment and reduce pollution, many governments have promulgated a series of laws and regulations and introduced some encouraging policies to promote the development of gas vehicles, such as formulating stricter emission standards for automobile exhaust and giving preferential policies for funds and taxes in natural gas supply, automobile purchase tax, equipment supply and gas station construction.
In 1992, the American federal government promulgated the Energy Policy Act, which made detailed provisions on tax reduction and exemption for purchasing or refitting alternative fuel vehicles and building filling stations, and also promulgated the tax reduction policy for using natural gas, exempting natural gas companies from automobile fuel sales tax. According to the policies and laws of the federal government, more than 40 states have formulated their own policies and measures to force and encourage the use of clean fuel vehicles such as CNG, which has promoted the development of CNG vehicles and the construction of filling stations. At present, there are more than 40 countries with gas vehicles in the world, mainly in Italy, New Zealand, Argentina, Brazil and other countries with rich natural gas resources and countries with strict environmental protection laws and regulations, such as the United States and Japan.
2. Development of natural gas vehicles in China.
In the mid-1980s, China introduced some CNG filling station equipment and established China's first CNG filling station in Sichuan. 1993 China petroleum and natural gas group co., ltd introduced foreign related technologies into the system, 1996 introduced domestic technologies and standardized technical standards of gas filling station devices and automobile modified parts. 1999 the national leading group for clean vehicle action coordination was established, which started the promotion and application of clean energy in pilot cities such as Beijing, Tianjin, Shanghai, Xi and Shenzhen 12, and achieved unprecedented results in the promotion and application of CNG vehicles and the construction of filling stations. According to the statistics of relevant departments, as of 2004, there were more than 200,000 natural gas vehicles and more than 700 filling stations in some areas of China.
2. Comparison of environmental and economic benefits between 2.CNG and other fuels.
Compressed natural gas vehicle:
Natural gas is compressed to 20MPa in compressed natural gas cylinders for automobiles, and then supplied to internal combustion engines through pressure reducers.
Compared with gasoline, CNG as automobile fuel has the following advantages:
L, reduce pollution, improve the atmospheric environment: natural gas is a clean energy, with the characteristics of high calorific value, high efficiency, little pollution, relatively complete combustion, and difficult carbon deposition. The emissions of CO, nitrogen oxides and particulate matter are lower than those of gasoline, and the tail gas pollution is obviously reduced. Automobile exhaust is one of the main sources of urban air pollution, and the main harmful components are carbon monoxide (C0), hydrocarbons (HC), nitric oxide (NO) and nitrogen dioxide (NO2). According to relevant data, compared with gasoline, using natural gas as automobile fuel can reduce the emissions of 90% CO, 90% SO2, 72% HC, 39% NOx and 24% CO2, and there is no dust, which has a significant effect on improving the urban environment. See Table L for the comparison of typical diesel engines with gasoline engines and natural gas engines.
2.CNG cars have high safety.
Compared with gasoline, compressed natural gas is a relatively safe fuel.
The lower explosive limit of (1) natural gas is 5%, which is higher than that of gasoline (the lower explosive limit is L%), and the ignition point of methane is 645℃, which is 2 18℃ higher than that of gasoline, so it is not easy to ignite. The density of methane is low, and the relative density is about 0.55. The leaked gas will soon be released into the air, so it is difficult to form the conditions of hot combustion in the natural environment. Once compressed natural gas leaks from a storage tank or pipeline, a low temperature zone will immediately form around the leakage point, making it difficult for natural gas to burn. Therefore, CNG is a fairly safe automobile fuel. Table 2 compares the fuel characteristics of natural gas and gasoline.
(2) Gas cylinders of natural gas vehicles are high-pressure containers.
(20MPa), its material, manufacture, inspection and test are strictly controlled in all countries. China has the standard of compressed natural gas cylinders for automobiles (GBL 7258- 1998).
Gas cylinders are equipped with explosion-proof facilities, pressure reducers, valves and other equipment. The air tightness standard is high, the air supply system is safe and reliable, and there will be no fire or explosion caused by car collision or overturning. The fuel tank of gasoline automobile is a non-pressure container, which is easy to explode after fire.
3. It is conducive to alleviating the contradiction between supply and demand of energy shortage.
China's economy is in a high-speed development stage, the number of automobiles is increasing at a rate of more than 1 10,000 vehicles per year, and the demand for gasoline resources is greatly increased. China needs to import a lot of crude oil, refined oil and liquefied petroleum gas every year. The use of gas vehicles can be optimized.
The structure of automobile fuel supply has changed the pattern that automobile fuel only contains gasoline and diesel, which not only relieves the shortage of gasoline supply, but also meets the needs of transportation development.
And 4, the service life of the engine can be prolonged. Natural gas is easy to diffuse and enter the engine in gaseous state, and it is easy to mix with air evenly in the engine, and the combustion is relatively complete and clean; It can improve the thermal cycle efficiency, accelerate the combustion speed and make full use of the combustion heat energy; At the same time, CNG has high octane number and good antiknock performance. When in use, antiknock agent does not need to be added, and lubricating oil will not be diluted, thus greatly reducing the wear of parts in the engine cylinder and greatly prolonging the service life of the engine and lubricating oil. All these will reduce the maintenance and operation costs of the car, thus improving the economy of the car. 5. It has high economic benefits. At present, domestic gasoline prices continue to rise, and the price system has been in line with the world. Using CNG vehicles will save nearly 40% of fuel costs, as shown in Table 3.
Third, the development prospect of compressed natural gas vehicles
CNG vehicles and filling stations have broad development prospects, mainly in the following aspects:
L, the rapid growth of car ownership and the grim situation of oil resources and environmental protection determine that the development of natural gas vehicles has become an important way to solve energy and environmental problems.
2. During the 11th Five-Year Plan period, new clean energy vehicles have been included in the national long-term scientific and technological development plan. The state will continue to organize and implement major scientific and technological projects involving all kinds of clean energy vehicles, focusing on supporting key technologies such as complete vehicles and parts, including natural gas vehicles, which will further promote the development of natural gas vehicles.
3. The large-scale development of natural gas resources and the acceleration of pipeline construction in China make it possible to develop CNG and filling stations. According to China's natural gas utilization plan, a large number of gas pipelines such as "West-to-East Gas Transmission" and "Shaanxi-Beijing Second Line" and gas pipelines in cities along the line have been built one after another in the past decade, and the infrastructure for large-scale utilization of natural gas in China has been gradually improved, and natural gas filling stations will gradually form a network.
4. The development of 4.CNG automobile has a stable gas source. Taking Tianjin as an example, Tianjin has established a perfect natural gas transmission and distribution system to supply gas to Tianjin from northern Shaanxi, Dagang, North China and other oil fields. In 2005, the gas supply was nearly 600 million cubic meters, and it is expected to reach 800 million cubic meters in 2006. The length of the pipe network is 6894km, of which the high-pressure pipeline is 59 1km, which is a great effort of Tianjin during the Eleventh Five-Year Plan period.
Four. Discussion on development countermeasures of CNG vehicles and filling stations
In order to accelerate the development of clean cars fueled by natural gas, the following suggestions are put forward:
1. Government's encouragement and support policies: The development experience of countries all over the world shows that government support is a necessary condition for accelerating development, and its economic policy is an important factor affecting its development and should be guaranteed by law. In the production, modification, spare parts production, gas station construction, gas vehicle purchase and use, maintenance and other links, preferential policies should be formulated in terms of price, tax, investment, subsidies and so on. Gas price is an important factor affecting the development of gas vehicles. Only when the price difference between gas and gasoline is large enough can the development of gas vehicles have economic basis and power.
2. Strengthen leadership and implement unified management. To develop CNG vehicles, we must build high-quality and convenient filling stations, and need the support of planning, public security, fire protection, labor and technical supervision.
3. Urban planning should consider the gas filling station and gas station as a whole, with reasonable layout and coordinated development. Make full use of existing land resources and build an oil-gas integration station on the premise of ensuring environmental safety.
4. Following the principle of synchronous development of CNG vehicles and gas filling stations, CNG vehicles can really develop only if gas filling stations are networked. At the same time, only when the scale of CNG vehicles reaches a certain number can the filling stations operate normally and achieve profitability.
5. Strict legal system: formulate strict automobile exhaust emission regulations, ensure that substandard vehicles are not allowed to go on the road, and strictly examine and certify the qualifications of CNG automobile modification plants. First of all, city buses and taxis should be the focus of the development of CNG vehicles to avoid some buses emitting black smoke and polluting the environment.
6. Increase publicity. At present, natural gas vehicles are still in their infancy, and the public has not fully understood their environmental protection, safety, economy and reliability. Therefore, it is necessary to carry out extensive social propaganda, strive to improve people's understanding of the harm of automobile exhaust, and make people understand that CNG is a clean, safe and economical vehicle fuel, and the development of natural gas vehicles will be recognized and supported by all sectors of society.
Compressed natural gas vehicles will become a new field of natural gas market development and application because of its remarkable economic and social benefits. With more and more attention paid to environmental protection, with the development and application of natural gas resources, it will be a reliable guarantee to alleviate the pressure of environmental pollution, alleviate the shortage of oil and realize sustainable development.
This paper expounds the development prospects and countermeasures of compressed natural gas vehicles (CNG) for environmental protection, low pollution, safety and economy, and CNG vehicles and filling stations.
Keywords: compressed natural gas vehicle; Station; Development prospect; counter-measure
At present, the major cities in China are the main sources of air pollution emitted by automobiles in a city. Therefore, the development of clean energy vehicles has become a delay. Compressed natural gas vehicle (CNG) is welcomed by all countries because of its low energy consumption and small displacement, and it is recognized as the best alternative energy vehicle in the world. Developing natural gas vehicles is of great significance for solving environmental and energy problems.
First, develop natural gas vehicles.
L, the development of foreign natural gas vehicles
To reduce pollution and protect the environment, many countries have promulgated a series of government regulations and introduced some encouraging policies to promote the development of gas vehicles, such as formulating stricter vehicle emission standards, providing subsidies for natural gas supply, car purchase taxes and fees, equipment supply, gas station construction and tax incentives.
In 1992, the federal government of the United States promulgated the "Energy Policy Act", or revised the detailed provisions on tax reduction and exemption for the purchase of alternative fuel vehicles and the construction of gas stations, and also promulgated a tax reduction measure, that is, companies that use natural gas are exempted from automobile fuel sales tax. According to the policies and laws of the federal government, more than 40 states have formulated mandatory national policies and measures to encourage the use of clean fuel compressed natural gas vehicles, such as policies and measures, to promote the development and construction of compressed natural gas vehicle filling stations. At present, there are more than 40 countries in the world with gas vehicles, mainly in Italy, New Zealand, Argentina, Brazil and other countries with rich natural gas resources, and the United States, Japan and other countries with stricter environmental regulations.
2. Development of natural gas vehicles in China.
In the mid-1980s, we introduced some CNG filling station equipment and established the first CNG filling station in China in Sichuan. In 1993, China petroleum and natural gas group company expounded the installation of imported technology system in 1996, and the imported technology and standardized technical standards for refitting the filling station into automobile parts. 1999 the national leading group for clean vehicle action coordination was established, which started Beijing, Tianjin, Shanghai, Xi' an, Shenzhen and other cities to promote the application of clean energy in the 12 pilot area, and made unprecedented achievements in the promotion and application of CNG vehicles and filling stations. According to relevant statistics, as of 2004, there were more than 200,000 natural gas vehicles in China, exceeding 700 gas filling stations in some areas.
2. Comparison of environmental and economic benefits between CNG fuel and other fuels
Compressed natural gas vehicle:
The 20MPa compressed natural gas in the car is transported to the compressed natural gas cylinder in use, and then supplied to the internal combustion engine through the pressure reducer.
Compared with gasoline, CNG-fueled cars have the following advantages:
L, reduce pollution, improve the atmospheric environment: natural gas is a clean energy, with high calorific value, high efficiency and no pollution. Compared with gasoline, it burns completely, does not deposit carbon, carbon monoxide, nitrogen oxides and particulates, and obviously reduces exhaust pollution. Vehicle exhaust is the main source of urban air pollution, and one of the harmful components is carbon monoxide (C0), hydrocarbons (HC), nitric oxide (NO) and nitrogen dioxide (NO2). According to the data, compared with gasoline as fuel, using natural gas as fuel can reduce the emission of carbon monoxide by 90%, sulfur dioxide by 90%, hydrocarbons by 72%, nitrogen oxides by 39% and carbon dioxide by 24%, which has a great effect on improving the urban environment. The emissions and gas engines of typical diesel engines and gasoline engines are shown in Table L.
2. CNG vehicles are safer.
Compared with gasoline, compressed natural gas is a relatively safe fuel.
(1) The explosion limit of natural gas is 5% higher than that of gasoline (the lower explosion limit is l%), and the ignition temperature of methane is 645℃, which is 2 18℃ higher than that of gasoline, so it cannot be ignited. The density of methane is low, and the relative density is about 0.55, which causes the leaked gas to be distributed in the air soon, so it is difficult to form high-temperature combustion conditions in the natural environment. Once compressed natural gas leaks from the storage tank or pipeline, a low-temperature zone will immediately form around the leakage, making it difficult for natural gas to burn. Therefore, it is a quite safe CNG automobile fuel. The fuel properties of natural gas and gasoline are shown in Table 2.
(2) Gas cylinders and pressure vessels of natural gas vehicles
(20MPa), and its materials, manufacture and testing are strictly controlled by all countries. In China, there is the Vehicle Standard for Compressed Natural Gas Cylinders (GBl7258- 1998).
Gas cylinders are equipped with explosion-proof facilities, pressure reducers, valves and other equipment, and the standards are strict and high. The gas supply system is safe and reliable, and will not be overturned or cause fire or explosion due to vehicle collision. The fuel tank of motor vehicles is a non-pressure vessel, which is easy to explode after fire.
3. It is conducive to alleviating the contradiction between energy supply and demand.
China's economy is in a stage of rapid development, the number of automobiles is increasing at a rate of 1 10,000 vehicles/year, and the demand for gasoline resources is greatly increased. China needs to import a large number of crude oil, refined oil and liquefied petroleum gas every year. Optimize the use of gas vehicles
The supply structure of automobile fuel has changed the mode that the automobile fuel is only gasoline and diesel, which not only relieves the problem of gasoline shortage, but also meets the needs of the development of transportation.
4. Extend engine life. Natural gas diffuses into the gas entering the engine, which is easily mixed with the air in the engine and burns completely clean; It can improve the thermal cycle efficiency, accelerate the combustion speed and make full use of the combustion heat; The octane number of CNG rises with high performance at the same time. When the agent does not need to add the uprising, it will not dilute the lubricating oil, which will greatly reduce the wear and tear of the parts in the engine cylinder, and prolong the service life of the oil. All these vehicles will reduce the maintenance and operation costs, thus improving the economy of vehicle use. 5. It has high economic benefits. At present, the domestic gasoline price continues to rise, and this price system and the cars that have used CNG in the world will be able to save nearly 40% of fuel costs, as shown in Table 3.
Third, the development prospect of compressed natural gas vehicles
CNG vehicles and filling stations will have broad development prospects, mainly in the following aspects:
The rapid growth of automobile oil resources and the grim situation of environmental protection determine that the development of natural gas vehicles has become an important way to solve energy and environmental problems.
2. During the Eleventh Five-Year Plan period, new clean energy vehicles have been included in the National Medium-and Long-term Science and Technology Development Plan, and the state will continue to organize and implement various major science and technology projects for clean energy vehicles, with emphasis on supporting complete vehicles and parts including natural gas vehicles. Will further promote the development of natural gas vehicles.
3. The large-scale development of natural gas resources and pipeline construction in China have accelerated the development of CNG and LPG filling stations, making it possible. According to China's natural gas utilization plan, in the past decade, a large number of gas pipelines and cities along the gas pipelines, such as "West-to-East Gas Transmission" and "Second Shaanxi-Beijing", have been built one after another, and China's natural gas utilization infrastructure has been gradually improved, and natural gas filling stations will gradually form a network.
4, develop the stability of CNG vehicle gas source. Take Tianjin as an example. At present, Tianjin has established a perfect natural gas transmission and distribution system, which is supplied by northern Shaanxi, Dagang, Tianjin and North China oil fields. The gas supply volume is nearly 600 million m3 in mid-2005, and it is expected to reach 800 million m3 in 2006. The pipe network length is 6894km, of which the high-pressure pipeline is 59 1km, which is the largest in Tianjin during the Eleventh Five-Year Plan period.
Fourth, the development of CNG vehicles and gas stations countermeasures
In order to accelerate the development of vehicles using natural gas as clean fuel, the following suggestions are put forward:
1, government policy encouragement and support: the development experience of countries all over the world shows that government support is a necessary condition for accelerating development, and its economic policy is an important factor affecting its development, which should be guaranteed by law, and preferential policy support should be given in terms of price, tax, investment and subsidy in gas vehicle production, modification, spare parts production, gas station construction, automobile purchase and use, maintenance and so on. Gas price is an important factor affecting the development of gas vehicles. Only when the difference between gas price and gasoline price is large enough can the economic foundation and power for the development of gas vehicles be formed.
2. Strengthen leadership and implement unified management.
The development of CNG vehicles requires the technical support of planning, public security, fire protection, labor and competent departments to build high-quality and convenient filling stations.
3, in the municipal planning, gas stations and filling stations should be considered as a whole, rational layout, coordinated development. In order to make full use of existing land resources and ensure the safety of oil and gas environment, a gas station will be built.
4. Following the principle of synchronous development of automobiles and CNG filling stations, only when the filling stations are networked can CNG automobiles really develop. At the same time, only when the scale of CNG vehicles reaches a certain number can the filling stations operate normally and make profits.
5. Strict legal system: formulate strict automobile exhaust emission regulations, ensure that cars that fail to meet the standards are resolutely off the road, and strictly review and certify the modification qualifications of CNG vehicles. First of all, cities should take city buses and taxis as the development focus of compressed natural gas vehicles, and some black smoke from bus stops pollutes the environment.
6. Increase publicity. At present, natural gas vehicles are still in the initial stage, and the public does not fully understand their environmental protection, safety, economy and reliability. Therefore, it is necessary to carry out extensive social publicity, strive to raise people's awareness of the harm of automobile exhaust, make people realize that CNG is a clean, safe and economical fuel, and make the development of natural gas vehicles recognized and supported by all sectors of society.
Because of its remarkable economic and social benefits, compressed natural gas vehicles will become a new application field in the development of natural gas market. With the increasing importance of environmental protection, with the development and application of natural gas resources, this will reduce environmental pressure and be a reliable guarantee for alleviating oil shortage and realizing sustainable development.