Turkmenistan has huge reserves of natural gas. Local authorities take all necessary measures for the consistent development of the domestic fuel and energy complex. In the future, the natural resources of the Central Asian state can stimulate the domestic production of new alternative fuels.
In his new analytical article, Allaberdi Ilyasov, a well-known Turkmen scientist, doctor of technical sciences, and a columnist of CentralAsia.news spoke in detail about the opportunities in the corresponding direction.
Perfect energy carrier
Turkmenistan holds the world’s fourth proven natural gas reserves, today it ranks among the main suppliers of gas in the Central Asian region. This hydrocarbon plays the same role in the world economy and energy of the 21st century that oil played in the previous century. In terms of reserves, the efficiency of extraction and use, and ecological properties, it is the most promising resource capable of meeting the needs of mankind in energy and hydrocarbon raw materials, at least during the current century.
Natural gas appeared in the arena of world energy relatively late, only in the second half of the twentieth century, and unlike coal and oil, it never acted as the main energy carrier. However, its proven world resources are large (about 155 trillion m3) and they are constantly increasing. At the beginning of last year, in the territories adjacent to the «Malay» and «Nayip» gas fields in Lebap province, Turkmenistan, a new dome in the lower layers of the «Northern Dervish» and «Malay» fields was discovered. Initial appraisal work showed that their gas reserves amount to 30 and 21.7 billion cubic meters.
Today, natural gas is the primary raw material for the creation of promising types of alternative synthetic motor fuels, and above all for the production of dimethyl ether (DME), an environmentally friendly product without sulfur. As an alternative to traditional diesel fuel, it is attracting more and more scientists’ attention from around the world.
In recent years, much attention has been paid to the search for new alternative fuels of non-petroleum origin for internal combustion engines. This is due, firstly, to the depletion of oil reserves on Earth, and secondly, to the increasingly negative impact of road transport on the environment. As a «food» for motors, natural gas, alcohols (methanol, ethanol), hydrogen, rapeseed oil, etc. are more often considered. But recently, the question of using dimethyl ether as a gas station for diesel cars and buses operating in urban areas where particularly stringent requirements for the emission of toxic substances are imposed.
Work in this direction in recent years has been intensively carried out abroad (USA, Denmark, Austria, Sweden). In the spring of 1995, at the International Congress and Exhibition in Detroit, a group of world-famous companies Amoco Co., AVL Powertrain Engineering Inc., specializing in oil and gas processing, catalysis, engines, and transport, announced a new environmentally friendly diesel fuel — dimethyl ether. The main modern technologies for its production are processes based on the conversion of synthesis gas. Their results show that it is perfect for diesel engines, providing virtually smokeless engine operation due to the presence of 35 percent oxygen.
Notes for ecologists
The main reason for the annual deteriorating environmental situation in the world is the continuous growth in the number of car parks. Soon, annual sales of passenger cars alone may rise to 126.9 million units. With this indicator, by 2035 the world fleet will reach 2 billion. Ecologists are not in vain to sound the alarm. In the emissions of pollutants into the atmosphere by all man-made sources, the share of motor vehicles reaches an average of 43 percent, greenhouse gasses — about 10 percent, in the mass of industrial waste — two percent, in the discharge of harmful substances with sewage — about three percent, in the consumption of ozone-depleting substances — about five percent.
The current situation dictates that adequate measures be taken. One of the most effective ways is the use of alternative environmentally cleaner types of motor fuel. They are considered one of the main ways to reduce the negative impact of cars on the environment. Therefore dimethyl ether deserves attention among promising alternative fuels for internal combustion engines. It is currently the only synthetic product that provides a complete replacement for traditional diesel fuel. Interest in dimethyl ether is also explained by the fact that in recent years new technologies for its production from methane have been developed in the world.
Scientific research proves that the use of dimethyl ether as a motor fuel for diesel engines is the basis for optimistic forecasts. DME has advantages over diesel and alternative fuels. Its advantages include a reduced tendency to soot formation during combustion, the almost complete absence of exhaust smoke, and good self-ignition in a diesel engine. Its use can significantly reduce harmful emissions with exhaust gasses and meet the most stringent future standards. It is non-toxic, provides lower carbon dioxide emissions, and exhaust gasses using this fuel are less prone to the formation of photochemical smog. A comparison of its properties with traditional diesel and other alternative fuels — methanol, ethanol, methane — shows that DME as a fuel for a diesel or compression engine is superior to any, including traditional ones. The lower calorific value compared to diesel fuel is partly compensated by the greater efficiency of the engine and the absence of power consumption for exhaust purification.
The environmental, safety, and health issues associated with handling dimethyl ether have been well studied by the industry with CFC aerosol as an example. (CFCs, or chlorofluorocarbons, are gaseous chemicals composed solely of chlorine (Cl), fluorine (F), and carbon ©) Currently, about four billion pieces are produced annually in Europe alone. According to its chemical formula, dimethyl ether is the simplest ether, it is non-toxic and does not pollute the environment, has a very short half-life (less than a day), is not carcinogenic, and does not cause mutations. However, a question arises that will need to be answered before giving preference to this particular fuel: Are changes to the design of the engine and its power system required to operate on this gas? Currently, active research aimed at solving the problem is being carried out in the world, and certain successes have been achieved. Existing types of diesel can be converted to new operations without major modifications by replacing the fuel system alone.
At the same time, it was revealed that the efficiency of a diesel engine was preserved, and in some modes even improved by up to five percent, an increase in its effective efficiency compared to operation on diesel fuel. In terms of energy intensity, dimethyl ether significantly exceeds diesel fuel: the cetane number (characteristic of the flammability of diesel fuel) is 55-60 versus 40-45 for diesel fuel, the ignition temperature is 2350 °C versus 2500 °C for diesel fuel. Such properties make it easy to start a diesel engine at low ambient temperatures, which is important for the northern countries of the world. Therefore, the positive characteristics of dimethyl ether put it in one of the first places on the list of alternative fuels for diesel engines. The presence of an oxygen atom in its composition ensures smokeless combustion of fuel, the excellent cold start of the engine, and noise reduction. The main advantage of DME as a diesel fuel is environmentally friendly exhaust. It is non-toxic and does not pollute the environment.
History of the issue
For the first time, dimethyl ether began to be used in the 20th century as propylene in aerosol cans. In general, chlorofluorocarbons (and DME in particular) belong to the group of halocarbons, which are part of the group of gasses and are non-toxic and non-flammable. They were created as an alternative to various chemicals used in refrigerators in 1928. They have also been used as propellants in insecticides, paints, hair conditioners, and other health care products. Between the 50s and 60s of the last century, they were used in air conditioners for homes, cars, and offices. All this led to the global spread of chlorofluorocarbons.
At that time, the use of these chemicals increased by about a million metric tons, which were produced annually only in the United States of America. Later, its consumption increased even more. It has reached the point where it has been used as an aerosol, refrigerant, and blowing agent for foams, packaging material, and in solvents.
In the second half of the 20th century, dimethyl ether became of great practical importance in a wide range of applications, beginning with a successful first practical introduction in the early 1960s by AkzoNobel (Netherlands) as a propellant in aerosol cans. At the same time, Soviet scientists obtained it as a by-product of methanol synthesis. Dehydration of methanol to obtain dimethyl ether is historically the first way to carry out this synthesis. Many works of Soviet and foreign scientists have been devoted to this process since the 1960s, in 1970-1975. And even then, dimethyl ether was first used in engines used in the Far North.
The gas world
Municipal bus fleets in many cities in Denmark and Sweden have already been converted to DME. It is of great interest in Asian countries, primarily in China, where it is used as household bottled gas, instead of diesel fuel and as fuel for power plants. In the People’s Republic of China, the main raw material for the production of dimethyl ether is coal. The first industrial plants for the production of DME from coal were built in China in 2003. By 2007, their capacity had grown to 400,000 tons/year. In the Celestial Empire, dimethyl ether is supposed to be used as diesel fuel and as liquefied hydrocarbon gasses for domestic purposes.
This chemical element is an excellent gas fuel for turbojet engines due to emission properties comparable to natural gas. Calculations by Japanese researchers have shown that, on a large scale of production, the use of DME as a fuel for gas turbine plants is more economical than liquefied gas.
This is because transportation and storage are much cheaper than liquefied or compressed gas. Japan has even more experience than China in developing technologies for the production of DME.
The production of DME in the world over the past few years has increased significantly and currently amounts to tens of millions of tons. In addition to the Land of the Rising Sun, where several pilot plants for the production of dimethyl ether have been built and an industrial plant is being built, and the previously mentioned China, such states as Iran, Trinidad and Tobago, Oman, Nigeria, Qatar, Egypt with natural gas reserves, are also showing interest in the production of DME as a substitute for diesel fuel, domestic gas, and energy fuel. The largest producers apart from China are Japan, South Korea, and Brazil. Questions about the international standardization of dimethyl ether and fuel equipment for its use are raised.
Tasks and their solutions
High-quality processing of natural gas is the most urgent task of the petrochemical industry. And the synthesis of dimethyl ether is one of the new directions in this area. Today, approximately 80 percent of the dimethyl ether produced in the world is used to produce aerosols instead of freon. Market conditions and product prices directly depend on the state of affairs in the methanol market, the feedstock for its production. Its properties also allow it to replace liquefied gas for heating and cooking. China is the largest consumer of this product — its share in the global consumption structure is about 90 percent. The Celestial Empire already consumes a large amount of dimethyl ether in the form of a mixture with gas for these purposes.
In general, in recent years, special attention in many countries has been paid to the production and use of biofuels, which in the 21st century can have a significant impact on the development of energy, and sustainable energy supply systems in different regions and contribute to the diversification of the types of fuel used. In the future, a significant increase in the share of electricity and heat generation from non-traditional and renewable energy resources is expected. One of them is dimethyl ether.