What is compressed and liquefied gas. Fuel for cars. Liquefied, compressed gas

Gaseous hydrocarbons produced from gas and gas condensate fields are usually called natural gas proper. Natural gas is currently one of the main household and environmentally friendly industrial fuels. It is also used as a raw material for the production of hydrogen, carbon black (soot), ethane, ethylene, acetylene.

Natural gas consists mainly of alkanes, represented primarily by normal hydrocarbons with 1 to 4 carbon atoms (CGC 4) and isobutane.

The main component of dry natural gas is methane (93-98%), in which the H: C ratio is 33%. The rest of the hydrocarbon components are contained in smaller quantities. Gaseous alkanes in natural gas have boiling points at normal pressure from -162 C to 0 C.

If in the XX century the main attention in the world was paid to the study, exploration, development of natural gas deposits, which are ordinary (traditional) gas-containing accumulations of hydrocarbons, then in the XXI century the economic situation already requires turning to significant potential natural gas resources, contained in unconventional sources, before total to natural gas hydrates (GT). GGs are a very significant and still underdeveloped source of natural gas on Earth. They can become a real competitor to traditional deposits due to their huge resources, wide distribution, shallow occurrence and concentrated state of gas (one cubic meter of natural methane hydrate in the solid state contains about 164 cubic meters of methane in the gas phase and 0.87 cubic meters of water).

A few years have passed since the discovery of the first deposits of natural gas hydrates. The priority in opening them belongs to Russian scientists. In March 2000, a Russian-Belgian expedition discovered a unique deposit of gas hydrates in the freshwater bottom sediments of Lake Baikal, at a depth of several hundred meters from the water surface. For the first time, large crystals of gas hydrates, up to 7 cm in size, were removed from the bottom of the lake.

Research carried out in different regions the world, it was found that about 98% of the GT resources are located in the waters of the world ocean (off the coasts of North, Central and South America, Japan, Norway and Africa, as well as in the Caspian and Black Seas) at water depths of more than 200-700 m, and only 2% - in the polar parts of the continents. According to weighted average estimates, the resources of gas hydrate deposits amount to about 21,000 trillion cubic meters. With the current level of energy consumption, even when only 10% of the gas hydrate resources are used, the world will be provided with high-quality raw materials for environmentally friendly energy production for 200 years.

According to the World Energy Council, until 2020, natural gas is presented as the most technologically prepared fuel for internal combustion engines both in terms of vehicle preparation, requiring minimum costs for converting a vehicle from liquid fuel to gaseous fuel, and in terms of natural gas reserves.

Both gas and petrol cars emit approximately the same amount of hydrocarbons into the atmosphere. At the same time, it is not the hydrocarbons themselves that are dangerous to human health, but the products of their oxidation. A gasoline engine emits a lot of various hydrocarbons, and a gas engine emits methane, which of all saturated hydrocarbons is the most resistant to oxidation. Therefore, the hydrocarbon emission of a gas vehicle is less dangerous.

In terms of natural gas reserves (mainly methane) and its production, Russia is in first place in the world.

The share of natural gas in the world's fuel and energy balance is very modest - 23%. And the growth rates of the gas industry in most countries of the world are also low. The exceptions are countries such as Russia, the Netherlands, Norway and a number of others, in which it can be considered that the "era of oil" has been replaced by the "era of natural gas" or "the era of methane".

When gas is used in carburetor engines, 1 m 3 for trucks, on average, replaces 1 liter, and for cars, 1.2 liters of gasoline.

Application of CNG for road transport can provide the creation of cars with a capacity 30-40% higher than modern cars running on gasoline, with an effective efficiency of up to 38-40% while simultaneously increasing the engine life by 1.5 times and the oil change time by two times.

The main disadvantage of natural gas as a motor fuel is, first of all, its lower (1000 times) volumetric energy density compared to liquid petroleum fuels - 0.034 MJ / l for natural gas, 31.3 and 35.6 MJ / l for gasoline and diesel fuel. ...

Natural gas itself is a very bulky fuel because its density is six hundred times lower than that of gasoline. To store it in a compressed state, you have to use special rather heavy cylinders. Massive gas cylinders installed on the car increase its weight and reduce the carrying capacity. The compressed gas is stored mainly in metal cylinders. the optimal high compression ratio of gas vehicle engines is not established due to the need to maintain the ability to quickly switch to gasoline, which leads to a decrease in engine power (up to 20%), as a result of which the maximum speed decreases by 5-6%, it is difficult to start the engine in the cold season (below 0 ° C), which is explained by the higher temperature of ignition and self-ignition of natural, therefore, gas fuel heaters are provided in the power scheme; in the absence of heating, it is possible to start the engine on oil fuel, followed by switching to gas after warming up the engine; the design of the fuel system becomes more complicated, its weight increases and the volume and cost of maintenance and repair increases by 3-10%;

According to safety regulations, the gas must be triggered before you park the car, and even more so in the garage. And at the beginning of the working day, you need to go to a specialized gas filling station for liquid fuel, which is very inconvenient.

Car exhaust gas catalytic converters designed for gasoline are ineffective in reducing nitrogen oxides and methane when running on natural gas. Improvement of engines and catalytic converters is needed. From an environmental point of view, a gas engine with a variable three-stage catalytic converter could be the most promising solution to achieve a reduction in emissions of all pollutants by more than 90%.

The use of natural gas in diesel engines is difficult due to its relatively high temperature self-ignition and, accordingly, a low cetane number. To overcome this difficulty, a so-called dual-fuel system is used - a small amount of diesel fuel is injected into the combustion chamber as an ignition charge, and then compressed natural gas is supplied. Sometimes it is necessary to install a spark ignition system. Diesel engines running on natural gas are widely used in the gas industry itself in piston gas pumping units and motor-toro generators with spark and pre-chamber-flare ignition.

It should be noted that gaseous fuel is the only type of alternative fuel for which technical and environmental problems of use have been largely resolved in Russia, although certain difficulties are caused by breaking the psychology of the consumer, with a prejudice regarding unfamiliar fuel.

The use of CNG in aviation makes it possible to radically change the environmental characteristics of exhaust gases, eliminate the deficit in aviation fuel for many decades, and significantly reduce fuel costs.

An analysis of the prospects for the use of natural gas on ships showed that this type of energy carrier can be recommended for use only on ships of the auxiliary fleet.

1.1.2 Methane-containing gases of coal seams and underground hydrosphere

Coal mine methane has found practical application. Recently, it has been quite definitely referred to as an alternative fuel for automobiles. Its amount is comparable to the resources of hard coal (104 billion tons).

Although some coal mine methane is mined in the world, it has already been used. By 1990, over 90,000 vehicles were running on CMM in the USA, Italy, Germany and Great Britain. In the UK, for example, it is widely used as a motor fuel for regular buses in the coal regions of the country. The methane content in mine gas ranges from 1 to 98%. As a motor fuel, the greatest interest is the gas extracted from coal seams, outside the zones of influence of mining operations, according to the technologies of coal and gas production. The essence of such a field is to extract gas by wells drilled from the surface, using methods to stimulate gas recovery, while mine gas contains 95-98% methane, 3-5% nitrogen and 1-3% carbon dioxide.

In Russia, coal mine methane, as a type of energy fuel and chemical raw material, attracts attention from the standpoint of potential reserves that have been identified to date.

It should be noted that the content of combustible gases in coal seams depends on the depth of development of reserves and increases as it increases. This leads to an increase in the intensity and volume of gas emission into mine workings.

At present, in Russia, coal mine methane contained in coal seams and surrounding rocks is extracted to the surface by vacuum pumping stations through specially drilled wells, and from the mine space it is released into the atmosphere through a ventilation system.

In all cases, the use of a methane-air mixture as an energy fuel is determined by its composition, i.e. the ratio of methane as such and air. The percentage ratio of these components determines the energy value of the methane-air mixture and the possibility of its use, especially in terms of explosion hazard during combustion.

Practice has confirmed that a methane-air mixture with a methane content in the range from 2.5 to 30% according to the existing classification is substandard and explosive when burned, and mixtures containing less than 2.5 and more than 30% pure methane are safe when burned in power plants. Both mixtures are certainly potential energy fuel sources.

Technical use substandard methane-air mixture consists in bringing the content of pure methane to standard levels (over 30% and less than 2.5%). This can be done, firstly, by improving the degassing systems, which make it possible to maintain the methane content in the mixture over 30%. However, the implementation of this path, judging by the share of substandard mine methane in the overall structure of methane yield, has certain difficulties. The second way is to increase the methane concentration by adding natural gas to the mixture. The third direction - reducing the concentration of methane to the lower explosive limit by diluting the mixture with air - is the simplest for practical implementation.

Currently, in Russia, the best successes in degassing and using coal mine methane have been achieved in the Vorkuta basin, where it is used in boiler houses, fire heaters and dryers. Modern technologies allow to efficiently extract methane in shallow coal seams of high thickness and high gas saturation, where it is possible to use methods to stimulate gas inflows to the bottom hole. Only a few carboniferous regions of the world meet these conditions, therefore, despite the high resources of coal bed methane, the actual gas production in the coming years is unlikely to exceed 5-10% of the total gas production.

Water-dissolved a dispersed gases of the underground hydrosphere(to a depth of 4500 m) are distributed almost everywhere in the earth's crust. Total gas resources in groundwater to depths of 4500 m, according to VNIGRI estimates, reach 10,000 trillion m / a to depths, on average, not exceeding 10 km,

The underground hydrosphere of the Earth, due to the high solubility in it of hydrocarbon and other gas components in geological time, is in a state of permanent, in some places progressive gas saturation mainly with hydrocarbons, which inevitably leads to the formation of zones of maximum gas saturation. The study of such zones, reliably established at the present time within young platforms, as well as existing at the ancient stages of the development of a number of regions, makes it possible to reveal the nature of the geochemical relationships between hydrocarbon deposits and gas-saturated groundwater.

to the scientific research in the field of oil and gas hydrogeology is the establishment of a general pattern, according to which industrial deposits of gas, and possibly oil," are a consequence of the global process of gas saturation of the underground hydrosphere.

The given schematic model corresponds rather closely to the natural conditions of the following specific gas-bearing provinces and gas-bearing regions.

Biogas

Earlier in Russia, no one seriously thought about gaseous fuels from local resources. A country with large reserves of oil and gas could afford it. In countries without natural resources, since the mid-1980s, all potential local sources of alternative motor fuels have been registered and put into production. These include, first of all, various types of biomass of plant and animal origin.

Biogas is a mixture of methane and carbon dioxide produced by the methane digestion of various biomasses. Methane fermentation - the result of natural biocenosis of anaerobic bacteria - takes place at temperatures from 10 to 55 ° С in three ranges: 10 ... 25 ° С - psychrophilic; 25 .40 ° С - mesophilic; 52 ... 55 ° С - thermophilic. System humidity is 8 to 99 %, the optimal value is 92 - 93%. The methane content in biogas varies depending on chemical composition raw materials and can be 50-90%.

Biogas in terms of industrial production and applications in engines Vehicle, is of serious practical interest for Russia. Our country annually accumulates up to 300 million tons (dry matter) of organic waste: 250 million tons in agricultural production, 50 million tons in the form of solid waste. This waste is an excellent raw material for biogas production. The potential volume of biogas produced annually may amount to 90 billion cubic meters, that is, 40 million tons of oil equivalent worth 20 billion euros. The total potential cost of the produced volume of biotoil (syngas and biogas) could be 35 billion euros per year.

Waste fermentation is best carried out in digesters - metal or reinforced concrete tanks with heating and stirring.

To produce biogas from municipal solid waste (MSW), they are first crushed, and then mixed in a digester with sewage sludge from sedimentation tanks treatment facilities... The gases contain up to 50% methane, 25% carbon dioxide, up to 2% hydrogen and nitrogen. This technology is widely used abroad - in the USA, Germany, Japan, Sweden.

Biogas is one of the most promising types of motor fuels produced from local raw materials in terms of industrial production and use in vehicle engines. In a short time, in many countries around the world, a whole industry for the production of biogas was created.

A significant part of the biogas produced is used to generate electricity.

Among the industrialized countries, the leading place in the production and use of biogas belongs to Denmark

As practice shows, the output of sewage gases from a processing station fed by a sewer network serving a settlement with a population of 100 thousand people reaches more than 2500 m 3 per day, which is equivalent to 2000 liters of gasoline.

The production of biogas also includes the production of landfill gas, or biogas from waste from landfills. Currently, in many countries, special equipped storage facilities for solid municipal waste are being created in order to extract biogas from them for the production of electricity and heat. Significant volumes of raw materials for fermentation are available in agriculture.

Biogas technologies are effective in any climatic region of vast Russia. In this way, gaseous fuels and highly efficient organic fertilizers are already being produced, which are so necessary for modern Russian agriculture.

However, the development of motor vehicle engines running on gas with a low calorific value, like biogas, presents certain difficulties. Therefore, it is more expedient to use not biogas, but biomethane obtained from it. For this, CO2 and other impurities are removed from the biogas. The produced gas (biomethane) contains 90-97% CH4 and has a calorific value of 35-40 MJ / m 3. Biogas purification from carbon dioxide can be carried out different ways... The most common: scrubbing of gases with liquid absorbers (for example, water), freezing, adsorption at low temperatures.

Biomethane, like other gas fuels, has a low volumetric energy concentration.

Liquefied gases

Similar information.

But the 1973 oil crisis renewed interest in gas in the auto industry.

Specifications

Performance properties

Methane fuel has a higher octane number and specific heat of combustion than fuel oil or liquefied petroleum gases and does not change physicochemical properties at low temperatures. The octane number of compressed natural gas is in the range of 110-125 and during combustion produces 48,500 kJ / kg, gasoline - 76-98 and 44,000 kJ / kg, propane-butane - 102-112 and 46,000 kJ / kg. However, CNG is inferior to gasoline and propane-butane in the calorific value of the stoichiometric mixture, and provides 6-8% lower performance in engines designed for 2 types of fuel.

Compressed natural gas vehicles have lower operating costs. The cost of 100 kilometers of mileage for cars, trucks and buses on CNG is 1.5-2.5 times lower than for vehicles powered by gasoline, diesel fuel or LPG. Methane does not form carbon deposits on pistons, valves and spark plugs, does not wash off the oil film from the cylinder walls, does not dilute the oil in the crankcase, due to which the vehicle's overhaul mileage increases by 1.5 times, the service life of engine oil, spark plugs and cylinder-piston group - by 1 , 5-2 times. Reducing the load on the engine also provides a 7-9 decibel reduction in noise.

Security

Compressed natural gas equipment has a multiple safety factor. Cylinders are tested for destruction when falling from a height, hit from a firearm, impact open flame, extreme temperatures and aggressive environments, as well as are located in statistically less likely to deform parts of the car: according to BMW, the probability of significant damage to these parts of the body is in the range of 1-5%. According to statistics, the American Gas Association compiled statistics based on the operation of 2,400 gas-fueled vehicles with a combined mileage of 280 million km in the 1990s - 2000s. The data showed that in 180 out of 1,360 collisions, the impact occurred in the area where the cylinders were located, but none were damaged, and in 5 cases gasoline ignition was recorded.

Environmental friendliness

Compressed natural gas is one of the most environmentally friendly fuels and complies with the Euro-5 / Euro-6 standard. Carbon dioxide emissions from CNG use are 0.1 grams per kilometer. CNG cars emit 2 times less nitrogen oxides into the atmosphere, 10 times less carbon monoxide and 3 times less other carbon oxides than cars with gasoline engines. The combustion of natural gas does not generate soot, and there are no lead and sulfur emissions. In general, the use of CNG provides 9 times less smoke in the surrounding air.

Standardization

The quality of CNG is regulated by the following national standards:

• GOST 27577-2000 “Compressed natural fuel gas for internal combustion engines. TU "(RF standard);
• J1616 1994 "Surface vehicle recommended practice - recommended practice for compressed natural gas vehicle fuel" (US standard developed by the SAE (Society of Automotive Engineers));
• SAE J1616 (US standard);
• CARB (CNG specification, USA, California);
• DIN 51624 "Automotive fuels Natural Gas - requirements and test procedures" (German standard);
• Legge 14 Novembre 1995 No. 481. "Disposizioni generali in tema di qualita del gas natural" (Italian standard setting norms for networked natural gas used for the production of CNG);
• Regulation of the Polish Ministry of Economy on the quality requirements for compressed natural gas (CNG) (Polish standard);
• GB 18047-2000 "Compressed natural gas as vehicle fuel" (China standard);
• SS 15 54 38 “Motor fuels. - Biogas as fuel for high-speed otto engines "(standard for compressed biomethane used as a motor fuel (types A and B); developed by the Swedish Institute for Standardization, adopted on September 15, 1999 and is generally recognized in European countries);
• PCD 3 (2370) C “Compressed natural gas (CNG) for automotive purposes. Specification "(Indian standard);
• PNS 2029: 2003 "Natural gas for use as a compressed fuel for vehicles - Specification" (Philippine standard);
• 10K / 34 / DDJM / 1993 (decree of Oil and Gas Director General, dated February 1, 1993) (Indonesian standard).

Technologies for processing and using natural gas, reflected in national standards, are summarized in the international standard ISO 15403 "Natural gas for use as a compressed fuel for vehicles". Its first part establishes requirements for natural gas indicators that ensure the safe and trouble-free operation of gas filling equipment and vehicle equipment, the second part establishes requirements for the quantitative values ​​of parameters that normalize the quality of natural gas as a transport fuel.

Usage

Cars

Gas vehicle engines are classified according to the number of fuels that are designed to be used. Gas (dedicated, monovalent) engines are designed directly to run on natural gas, which provides the highest efficiency. Typically, gas-powered vehicles do not have a petrol tank, but sometimes support the use of petrol as a backup fuel. Gasoline-gas (dual-fuel, English bi-fuel, bivalent) engines allow the use of both gas and gasoline. Most of the gasoline-powered vehicles are vehicles converted outside the manufacturer. Gas-diesel (eng. Dual-fuel) engines at low speeds consume more diesel, at high - more gas. Gas and gasoline-gas engines are most common on passenger cars and light trucks, gas-diesel engines are most common on heavy trucks.

Production vehicles running on compressed natural gas are produced by many automotive concerns, including Audi, BMW, Cadillac, Ford, Mercedes-Benz, Chrysler, Honda, Kia, Toyota, Volkswagen. In particular, in the segment of cars and light trucks, the market is represented by Fiat Doblò 1.4 CNG, Fiat Qubo 1.4 Natural Power, Ford C-Max 2.0 CNG, Mercedes-Benz B 180 NGT, Mercedes-Benz E200 NGT, Mercedes-Benz Sprinter NGT, Opel Combo Tour 1.4 Turbo CNG, Opel Zafira 1.6 CNG Ecoflex, Volkswagen Caddy 2.0 Ecofuel and Life 2.0 Ecofuel, Volkswagen Passat 1.4 TSI Ecofuel, Volkswagen Touran 1.4 TSI Ecofuel, Volkswagen Transporter Caravelle 2.0 Bensin / Gas, Volvo V70 2.5FT Summum and other models. Large freight and passenger vehicles powered by CNG are manufactured by Iveco, Scania, Volvo and other companies. The main Russian manufacturers of NGVs are GAZ Group, KamAZ and Volgabus. In total, about 150 models of gas equipment are presented on the Russian market, including KamAZ truck tractors, medium-tonnage GAZon Next CNG, low-tonnage GAZelle Next CNG and GAZelle-Business CNG, passenger cars Lada Vesta, Lada Largus, modifications of UAZ Patriot and other .

Many governments have resorted to institutional, regulatory and financial incentives to popularize gas fuels. Popular organizational measures include a ban on the use of diesel fuel on light and medium-duty vehicles or passenger capacity, within cities and environmental zones (Pakistan, Iran, South Korea, Brazil), a ban on the use of petroleum fuels in public and municipal transport (France ), priority access of companies-consumers of gas fuel to the municipal order (Iran, Italy). Regulatory measures mainly affect the design and construction of CNG filling stations and include bans on the construction of filling stations without a natural gas filling unit (Italy) or concessions on the construction of CNG stations within urban areas (Turkey, Austria, South Korea). Financial incentives include lump sum payments for refurbishment or purchase of new vehicles on CNG (Italy, Germany), subsidized loans for refurbishment (Pakistan), exemption of car owners from parking fees (Sweden), duty-free import of imported LPG equipment (European Union countries, Iran), refusal from the price pegging of gas fuel to petroleum (EU).

Water transport

Compressed natural gas is less common as a fuel for inland and maritime shipping than liquefied natural gas, which is more convenient for transportation and storage, but is used in dual-fuel propulsion systems. The gas is used as a navigable fuel on tourist ships in the United States (for example, the Elizabeth River I ferry with a capacity of 149 people) and Russia (Moscow and Neva-1), the Netherlands (Mondriaan and Escher, launched in 1994, Rembrandt and Van Gogh in 2000). Also in 2011, 11 CNG barges were in operation in Amsterdam. In Canada and Norway, CNG is used in a mixture with diesel fuel in the propulsion systems of bulk carriers and passenger ferries. Examples of CNG vessels include the M.V. Accolade II as well as M.V. Klatawa and M.V. Built in 1985, Kulleet has transported passengers and cars across the Fraser River near Vancouver for 15 years. In 2008, the Singapore-based Jenosh Group launched a container ship with gas cylinders loaded into standard 20-foot containers. In 2009-2010, the Chinese shipyard Wuhu Daijang built 12 such vessels for operation in Thailand and received an order for 12 more ships, and the Jenosh Group began developing a container ship with a cruising range of 1,500 nautical miles, targeted at customers in India, Pakistan, Indonesia and Vietnam.

Aviation

The compressed gas was not widely used as aviation fuel. In 1988, the Tupolev design bureau flew into the air an experimental Tu-155 on CNG, which was used for testing gas fuel: a smaller mass of gas could provide an aircraft with a larger payload. Compressed gas has the potential for small aircraft with relatively low fuel consumption. For example, in 2014, Aviat Aircraft launched the Aviat Husky, the first production dual-fuel aircraft.

Railway transport

Environmental safety and economic feasibility of using compressed natural gas contribute to its use in other modes of transport, including rail. In 2005, the world's first compressed gas train was launched in the central region of Peru. In January 2015, India's Minister of Railways inaugurated a diesel-CNG-powered train on the line between Rewari and Rohtak in Haryana State. Also in January 2015, a gas-powered train entered the line between the Czech cities of Opava and Hlučín.

Prevalence

Asia is the largest macro-region in terms of the number of CNG vehicles. ~ 15 out of ~ 24.5 million cars are concentrated there. About 5 million more are accounted for by the countries of Latin America. In Europe, CNG is used in 2 million vehicles. The countries of Africa and North America have a total of about 370 thousand cars.

Africa

Edition NGV Africa in November 2014 cited data according to which there were about 213 thousand CNG vehicles and 200 filling stations in Africa. From 2012 to 2016, the gas vehicle fleet in Africa grew by only 3%. De facto, the only developed market is Egypt, where infrastructure began to be developed in the mid-1990s and where by September 2014 there were almost 208 thousand LPG cars (slightly less than 3% of the country's total vehicle fleet) and 181 gas stations.

Elsewhere on the continent - Nigeria, South Africa, Mozambique, Algeria, Tanzania and Tunisia - the introduction of CNG is sporadic and mainly affects buses. In Nigeria, in the 2010s, a state program worth 100 million US dollars was launched to build a gas filling infrastructure, which should in the future increase the fleet of gas vehicles to several tens of thousands. The spread of CNG in Africa, including Egypt, is hampered by high price re-equipment of cars and construction of gas stations, since everything necessary equipment imported.

Oceania

The number of CNG vehicles in Oceania is extremely small. In New Zealand, against the backdrop of the oil crises of the 1970s and early 1980s, 120,000 vehicles, or 11% of the total vehicle fleet, were converted to CNG. With the abolition of government subsidies for the re-equipment of cars in 1986 and against the backdrop of falling oil prices, the CNG fleet gradually began to decline, and by 2016 the number of gas vehicles dropped to 65 units.

North America

From 2012 to 2016, the NGV fleet in North America grew by 26%. This growth is largely due to the low base effect - there are fewer CNG cars in North America than in Africa - only about 180 thousand cars.

Canada

In Canada, thanks to federal and provincial programs launched in the 1980s to research gas as a fuel and its introduction in road transport, the number of CNG-powered vehicles increased to 35,000 by the mid-1990s. Gas was widely used as fuel in regular buses. After the fall in oil prices, gas support programs were curtailed. Subsequently, against the backdrop of a limited supply from manufacturers of vehicles ready to use CNG, and a constantly shrinking infrastructure (from 1997 to 2016, the number of filling stations fell from 134 to 47), the fleet of gas vehicles decreased to 12 thousand units.

USA

As in Canada, the United States has since the early 1980s implemented programs to replace expensive fuel oil with gas. The number of CNG vehicles peaked in 2004 (121 thousand) and stopped growing. It wasn't until the 2010s that growth began, fueled by both environmental initiatives by states such as California, as well as a sharp drop in gas prices as a result of the shale revolution. In 2016, there were 160,000 gas vehicles and 1,750 gas stations in the United States. The highest density of the filling station network in 2013 was in Southern California. As of 2016, many private companies and governments in several states have announced plans to build a network of gas stations.

Per low prices gas was followed by demand from commercial companies. American manufacturers of auto components began to offer new equipment for trucks and buses. CNG-powered school buses were presented by Thomas Built Buses and Freightliner Custom Chassis Corporation. The demand for new developments was supported by the US Department of Transportation, which announced a $ 211 million grant to repair and upgrade school and commuter buses in 41 states. Some of the projects supported include replacing old diesel buses with new ones running on compressed natural gas. In 2016 transport companies FedEx and United Parcel Service expanded their gas vehicle fleet while building their own CNG filling networks for themselves.

The mass market for CNG was hampered by the limited supply of machines. In fact, the only CNG production vehicle was the Honda Civic. In 2012, Chrysler's CNG-powered Ram 2500 came out. For the 2014 model year, Ford introduced the F-150 bi-fuel pickup truck, and its bi-fuel rival, the Chevrolet Silverado, came out in 2015.

Latin America

Latin America is the second largest market after Asia. In 2016, there were about 5.5 million CNG vehicles. The country with the highest penetration of CNG as a vehicle fuel in South America is Bolivia: in 2016, 360 thousand vehicles were driven on CNG, that is, almost only 30% of vehicles. Moreover, this indicator for public transport was even higher - 80%. One of the reasons for the high penetration of CNG was that the Confederation of Drivers secured financing of the program for the conversion of vehicles to CNG from the state budget from taxes and fees on the sale of natural gas without additional payments from drivers.

As of 2016, in terms of the absolute number of cars on CNG, Bolivia is ahead of Colombia, where there were 543 thousand of them, as well as Argentina and Brazil with 2.295 million and 1.781 million cars on CNG, respectively. The widespread use of CNG in Argentina was facilitated by the policy of President Raul Alfonsin, carried out in the 1980s with the aim of replacing the increasingly expensive fuel oil. In Brazil, CNG was first used as a fuel for light vehicles in 1996, and before that, cars powered by bioethanol, obtained from sugar cane, were widespread in the country. Thanks to a number of government programs, the number of CNG vehicles reached one million in 9 years.

Europe

The European gas market is the third largest in the world, behind Asia and Latin America. As of 2016, there were more than 2.187 million gas-powered vehicles in Europe, up 25% in the previous four years. The total number of filling stations reached 4608.

EU and EFTA

In the European Union, the Directive of the European Parliament and the European Council 2014/94 / EU on the deployment of infrastructure for alternative fuels of 22 October 2014 is in force. The directive requires the EU member states to adopt national framework programs for the development of the market for alternative fuels and sets standards for the required number of refueling with alternative fuels based on the number of population and the distance of refueling from each other, provides for the application of common EU standards for filling stations and charging stations electric vehicles, sets out a way to communicate alternative fuels to consumers, including a methodology for comparing fuel prices clearly and clearly. The directive sets the following timelines for the development of CNG infrastructure in the EU: creation of sufficient infrastructure in urban and densely populated areas by the end of 2020, creation of a network of CNG filling stations along the TEN-T corridors (English) Russian by the end of 2025.

Russia

By October 2016, more than 145 thousand vehicles using CNG were registered in Russia.

Basically, natural gas in Russia is sold at automobile gas filling compressor stations (CNG filling stations), which are supplied with gas directly through gas pipelines. This decision was inherited from the Soviet Union, where the gas transport development program began in the 1980s. The program was developed for the future, since the USSR did not experience a shortage of petroleum products. The decision to create a network of CNG filling stations in the country was made in December 1983, at the same time the first station in the Moscow region was launched, located in the village of Razvilka at the intersection of the Moscow Ring Road and Kashirskoye Highway and designed for 500 gas stations per day. The station was equipped with Italian equipment, but Soviet-made compressors were already installed on the AGNKS-500 stations built in 1985-1987 on the Moscow Ring Road.

By the end of 2016, there were about 320 CNG filling stations. The largest owner and operator of CNG filling stations is Gazprom. For the comprehensive development of the NGV industry in December 2012, Gazprom created a specialized company, Gazprom Gazomotornoye Toplivo. By 2020, the company plans to expand its network to 480-500 points, as well as install CNG filling modules at existing liquid fuel filling stations of partner companies.

The largest consumers of NGV fuel in Russia are the Stavropol and Krasnodar Territories, the Sverdlovsk, Chelyabinsk, Kemerovo and Rostov Regions, as well as the republics of Kabardino-Balkaria, Tatarstan and Bashkortostan. In May 2013, the Government of the Russian Federation issued Decree No. 767-r, which sets targets for the use of natural gas in public and municipal transport for cities with a population of over 100 thousand people. To stimulate demand, by 2020 in these cities it is planned to transfer up to half of public transport and vehicles. utilities for natural gas. As part of this initiative, natural gas buses are already operating in a number of cities. In St. Petersburg, the first such buses appeared in 2013. Rostov-on-Don and Volgograd are planning to purchase more than 100 CNG buses for the World Cup.

Asia

Asia is the largest region in terms of the number of CNG vehicles. According to Asian NGV Communications, total number of such vehicles in 2016 is more than 16.4 million.The largest countries in terms of the number of vehicles on CNG are located in Asia: China (more than 5 million cars), Iran (more than 4 million), Pakistan (more than 3 million), India (more than 3 million) and Thailand (475 thousand). As of February 2017, there are more than 17.2 thousand gas stations in Asia.

Pakistan is the world leader in the gasification of vehicles (one third of the total vehicle fleet), overtaking Argentina and Brazil. Pakistan has developed the production of both light vehicles on CNG and trucks and buses, and the volume of production exceeds the volume of refurbishment. There are more than 2,300 CNG filling stations in the country, the construction of new ones is being subsidized, import duties on gas equipment have been canceled, the types of cylinders and sets of gas equipment are regulated at the state level.

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Sources of

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Natural gas, the main part of which is methane (92-98%), is by far the most promising alternative fuel for cars. Natural gas can be used as a fuel, both compressed (compressed) and liquefied.

Methane- the simplest hydrocarbon, colorless gas (under normal conditions), odorless, chemical formula - CH4. Slightly soluble in water, lighter than air. When used in everyday life, in the industry, odorants (usually thiols) with a specific "gas smell" are usually added to methane. Methane is non-toxic and harmless to human health.

Extraction and transportation

Gas is found in the bowels of the Earth at a depth of one to several kilometers. Before the start of gas production, it is necessary to carry out exploration work, which makes it possible to establish the location of the deposits. Gas is produced using wells specially drilled for this in one of the possible ways. Gas is transported most often through gas pipelines. The total length of gas distribution pipelines in Russia is more than 632 thousand kilometers - this distance is almost 20 times the circumference of the Earth. The length of main gas pipelines in Russia is 162 thousand kilometers.

Natural gas use

The field of application of natural gas is quite wide: it is used for heating premises, cooking food, heating water, producing paints, glue, acetic acid and fertilizers. In addition, natural gas in compressed or liquefied form can be used as a motor fuel in vehicles, special and agricultural machinery, railway and water transport.

Natural gas is an environmentally friendly motor fuel

90% of air pollution comes from vehicles.

Transfer of vehicles to environmentally friendly motor fuel - natural gas - allows to reduce emissions of soot into the atmosphere, highly toxic aromatic hydrocarbons, carbon monoxide, unsaturated hydrocarbons and nitrogen oxides.

When burning 1000 liters of liquid petroleum motor fuel, 180-300 kg of carbon monoxide, 20-40 kg of hydrocarbons, 25-45 kg of nitrogen oxides are emitted into the air together with exhaust gases. When natural gas is used instead of fuel oil, the emission of toxic substances into the environment is reduced by about 2-3 times for carbon monoxide, for nitrogen oxides - 2 times, for hydrocarbons - 3 times, for smoke content - 9 times, and the formation of soot, characteristic of diesel engines is absent.

Natural gas is an economical motor fuel

Natural gas is the most economical motor fuel. For its processing, minimal costs are required. Basically, all that needs to be done with the gas before refueling the car is compressing it in the compressor. Today, the average retail price of 1 cubic meter of methane (which in terms of its energy properties is equal to 1 liter of gasoline) is 13 rubles. This is 2-3 times cheaper than gasoline or diesel fuel.

Natural gas is a safe motor fuel

The concentration * and temperature ** limits of ignition of natural gas are significantly higher than that of gasoline and diesel fuel. Methane is twice lighter than air and dissolves quickly in the atmosphere when released.

According to the "Classification of combustible substances by the degree of sensitivity" of the Ministry of Emergencies of Russia, compressed natural gas is assigned to the safest, fourth class, and propane-butane - to the second.

* Formation of an explosive concentration occurs when the content of gas vapors in the air is from 5% to 15%. An explosive mixture does not form in an open space.
** The lower limit of autoignition of methane is 650 ° C.

Natural gas is a technological motor fuel

Natural gas does not form deposits in the fuel system, does not wash off the oil film from the cylinder walls, thereby reducing friction and reducing
engine wear.

The combustion of natural gas does not generate solid particles and ash, which cause increased wear of engine cylinders and pistons

Thus, the use of natural gas as a motor fuel can increase the engine's service life by 1.5-2 times.

The table below summarizes a few facts about CNG and LNG:

Compressed compressed gas is obtained in different ways: directly from gas wells as a product of oil refining and by fractionation of gas condensate or associated petroleum gas. Compressed natural gas can not only successfully replace liquid motor fuels, but also surpasses them in a number of parameters. Its main advantage is that compressed natural gas can be used in road transport without expensive technological processing.

The composition of natural gases produced in domestic fields is quite the same type. Basically (82-98%) it is methane CH 4 with small impurities (up to 6%) ethane C 2 H 6, up to 1.5% propane C 3 H 8 and up to 1% butane C 4 H 10. In associated gases produced in oil fields, depending on the production area, the content of methane can vary from 40 to 82%, and butane and propane - from 4 to 20%.

The main component, CH 4 methane, is characterized by the highest critical temperature (-82 ° C). Therefore, at normal temperatures, even at high pressures, methane cannot be liquefied: this requires a low temperature.

Methane properties are determined by its molecular structure. Gas belongs to simple hydrocarbons. Its molecule contains a maximum of hydrogen per carbon atom. This is the reason for the high thermal conductivity of methane, a wide range of flammability and a low content of toxic constituents. Due to the high content of hydrogen in the compressed gas, its more complete combustion in the engine cylinders occurs than that of HLL and gasoline. Compared to other hydrocarbon gases, methane is much lighter than air, so in the event of a leak it accumulates in the upper part of the room. High knock resistance of methane allows forcing the engine in terms of compression ratio (9.5-10.5).

In terms of energy parameters, 1 m3 of natural gas is equated to 1 liter of gasoline. At the same time, natural gas has a very low volumetric energy concentration. If the heat of combustion of 1 liter of liquid fuel is 31426 kJ, then for natural gas it is equal to 33.52-35.62 kJ, i.e. almost 1000 times less. Therefore, natural gas must be compressed to a high pressure.

At automobile gas filling compressor stations in Russia, the operating pressure is 20 MPa.

For compressed gas, gas cylinder installations (cylinders, fittings, a reducer, gas pipelines, etc.) are used, designed to work at high pressure - 19.6 MPa (200 kgf / cm 2). As the gas is consumed from the cylinder, the working pressure in it also decreases continuously.

CNG cylinders have a capacity of 34-400 liters and are designed for a pressure of 19.6 MPa.

Since the cylinders for storing compressed gas are thick-walled, a battery of eight such cylinders is rather heavy. Consequently, the payload capacity of vehicles also decreases. At the same time, the mileage of vehicles on CNG becomes 2 times less than on gasoline. Therefore, cryogenic technology for storing CNG on a car is considered more promising. In addition, this direction is considered a milestone on the way of creating hydrogen engines.

Compressed (compressed) natural gas (CNG) was previously called compressed natural gas (LNG) and is regulated in accordance with GOST 27577-2000 "Compressed fuel gas for internal combustion engines" determines the physicochemical and performance indicators of CNG (Table 5.7).

Table 5.7 Physical and chemical indicators and performance indicators of CNG

Note. The values ​​of the indicators are set at a temperature of 293K (20 ° C) and a pressure of 0.1013 MPa .

In accordance with GOST for CNG, the temperature of the gas filled into the car's cylinders must be no more than 40 ° C. At an ambient temperature above 35 ° C, the temperature of the gas to be charged should be no more than 5 ° C above the air temperature. The temperature of CNG during refueling is determined at the request of consumers.

CNG ignites at a temperature of 635-645 ° C in the combustion chamber of the engine, which is 3 times higher than the ignition temperature of gasoline.

This makes it difficult to start the engine, especially at low temperatures (below -5 ° C) ambient air. Therefore, cars have a backup gasoline supply system. At the same time, in terms of ignition and fire hazard, CNG is much safer than gasoline.

The positive factors of the use of CNG include the following:

The service life of engine oil is increased by 1.5-2.0 times due to the absence of its dilution and reduction of pollution; as a result, oil consumption is reduced by 30-40% compared to gasoline engines;

The service life of the engine increases on average by 35-40% due to the absence of carbon deposits on the parts of the cylinder-piston group;

The service life of spark plugs is increased by 40%;

The engine overhaul mileage is increased by 1.5 times;

The emission of harmful substances with exhaust gases, especially CO, is significantly reduced (up to 90%).

If the gas is used up, the engines of CNG gas vehicles can quickly switch to gasoline operation.

Along with the advantages, the following disadvantages can be noted:

The labor intensity of maintenance and repairs increases by 7-8%, and the price of a car increases by an average of 27% due to the presence of additional gas equipment;

Engine power is reduced by 18-20%. Traction-dynamic and performance characteristics cars: acceleration time increases by 24-30%; the maximum speed is reduced by 5-6%; the limiting angles of the climbs to be overcome are reduced by 30-40%; operation of a car with a trailer is difficult; the driving range with one gas filling is reduced (does not exceed 200-250 km);

The carrying capacity of the vehicle is reduced by 9-14% due to the use of high-pressure steel cylinders (their number and weight may be different);

The mileage utilization rate for gas-cylinder vehicles is reduced by 8-13% compared to gasoline vehicles;

Annual productivity when working on urban transport is reduced by 14-16% compared to gasoline.

The considered features of CNG as a fuel for automobiles make it possible to determine the rational area of ​​application of gas-cylinder vehicles: transportation in large cities and adjacent areas (priority importance of improving the air basin).

The efficiency of intracity transportation by gas-cylinder vehicles is obvious when servicing trade, household, communications and other institutions.

The basis of natural gas, which is of natural (natural) origin, is methane (CH4). Natural gas was formed through organic transformation. The methane content in natural gas can range from 91 to 99%, everything else is propane, ethane, butane, and nitrogen. This variation in percentage is explained by the difference in the chemical composition of gas produced in different parts of our Earth. However, when burned, natural gas of different origins gives off the same amount of heat, which makes geo-referencing absolutely unimportant for both you and your engine. Thanks to electronic sensors of LPG equipment, the composition of the gas is automatically determined, after which the proportion of the fuel mixture is adjusted, taking into account the characteristics of this gas.

Benefits of natural gas

The chemical composition of natural gas has a beneficial effect on the condition of the engine and does not entail problems associated with operation. Due to the absence of additives in the composition of methane, which are present in liquefied hydrocarbon gases ( LPG), the combustion products of natural gas do not contain harmful impurities. Moreover, when natural gas is burned, CO2 emissions are reduced by 25%.

The amount of methane in natural gas is like the octane number for gasoline, according to this parameter it is customary to characterize natural gas... What does this mean for the engine? The operation of the engine, as well as the likelihood of such a phenomenon as detonation, depends on this parameter.

Compressed natural gas(LNG) has a number of undeniable advantages over liquefied petroleum gas (LPG), including environmental friendliness and safety. Methane, which, as you already know, in natural gas most of all, dissolves quickly in the air, which practically negates the likelihood of the gas igniting in the event of damage. The way natural gas is stored minimizes the likelihood of an uncontrolled leak. Serviceable cylinders are required to withstand burst pressure of more than 600 bar, and thanks to the valve system, a controlled gas supply occurs.

When running on CNG, the engine can demonstrate high performance due to its high octane number (~ 130), especially when the engine is equipped with a turbine or exhaust gas recirculation system, or better, both together. Although it has and reverse side, for example, high gas consumption as well as heat dissipation problems. The engine noise level during operation on natural gas is reduced by 3 dB, therefore this type of fuel is very relevant for public transport. Compressed natural gas, like CIS can be used both on gasoline and, although in the case of diesels, you will have to face a low return on investment. The problem is that a diesel engine will need to be fitted with a spark ignition system or a mixed cycle in which diesel will act as an igniter.

There are also disadvantages to this type of fuel.

1. Low energy density. Because of this feature, natural gas is very often used in a compressed form. The pressure or compression ratio is 20 MPa or 200 bar. In terms of energy density, we get 7 kJ / dm3, in comparison with gasoline in which this figure is 30 kJ / dm3 can be obtained without any additional compression operations. This feature of natural gas leads to the fact that the engine, in order to run on this fuel, must be optimized for this, and at the same time it will be significantly higher. With equal sizes of gas (LPG and LNG), more can be traveled on LPG, therefore, in order to compensate for the low performance, those who want use methane as an alternative fuel, you have to put more gas tanks on your cars. This, as you understand, leads to an increase total weight car, and a decrease in free space in the trunk. High pressure required for storing LNG-filled tanks (usually cylindrical or round) make the tanks very bulky and take up a lot of space in the case of cars.

There are two types of systems capable of running on natural gas - monovalent and bivalent.

• Monovalent the type provides for the combustion of exclusively LNG, which comes from a special tank.
• Bivalent type provides for the simultaneous use of gas together with the main fuel, due to which there is an economy Money and the consumption of gasoline is reduced.