Are the advantages or disadvantages of developing alcohol-ether fuels greater?

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Author: Tang Hongqing (a technical expert at China National Synthetic Oil Engineering Co., Ltd., as well as the deputy chairman of the Technical Committee of the National Chemical Engineering Technology Center, and a member of the evaluation panel for projects in the energy technology field under the 11th Five-Year Plan and the 863 Program). Source: China Chemical Industry News. Date: 2009-03-09. Using coal-based alcohol ether fuels as alternative energy sources is a topic that has been discussed and debated in China for over twenty years; it is also a subject of controversy on an international scale. Over the past two years, as international oil prices have continued to fluctuate, it has become necessary for us to analyze alcohol-ether fuels: given the advantages and disadvantages associated with them, we need to determine whether the benefits of developing such fuels outweigh their drawbacks, or vice versa. Methanol fuel: The core dispute lies in environmental protection. In simple terms, methanol gasoline is gasoline to which a certain proportion of methanol is added, along with specific additives to address issues such as layering when exposed to moisture, metal corrosion, and rubber swelling. Methanol gasoline is indicated by the proportion of methanol mixed in; for example, 15% methanol mixed in is denoted as M15, while 85% methanol mixed in is denoted as M85. Pure methanol fuel is represented by M100. Domestically and internationally: divergent attitudes. Although methanol gasoline is unfamiliar to people in the consumer sector, research on it has actually been carried out for a long time at the **research level. It is reported that our country began to conduct systematic research on methanol fuel in the 1970s. In addition, our country also maintains long-term cooperation with German Volkswagen and American Ford Motor Company. In fact, provinces in China such as Shanxi are enthusiastic about using methanol as a fuel for vehicles; currently, M15 methanol gasoline with a low proportion of methanol has been introduced and used throughout Shanxi province. While research and demonstration on methanol gasoline were underway in China, research institutions abroad ceased their efforts one after another. On the one hand, international fuel standards have set limits on the methanol content ； On the other hand, major automobile manufacturers around the world have also begun to resist the use of methanol fuel. Methanol gasoline was immediately rejected abroad for several main reasons: the decline in world oil prices. After the two oil crises in the 1970s, the global supply and demand balance for oil was adjusted, resulting in a balance between oil supply and demand, which reduced the world’s enthusiasm for seeking alternative energy sources. The production cost of methanol is high. In the United States, methanol is primarily produced using natural gas as a raw material, which results in high production costs; as a result, it is not economical to use methanol as a substitute for gasoline, and therefore companies are not very enthusiastic about adopting it. The oil conglomerates are uncooperative; with soaring oil prices, U.S. oil companies can reap huge profits, which is why they are reluctant to invest in building storage facilities and filling stations for methanol fuel. Automobile manufacturers did not persist in this approach. By the late 1990s, their focus shifted to hybrid and fuel-cell vehicles, and they stopped further developing methanol flexible-fuel vehicles. The infrastructure has not kept up. In the United States, over 2/3 of oil and petroleum products are transported via pipelines, which are already at full capacity; investing heavily in building additional pipelines to transport large amounts of alternative fuels would require substantial costs. It has a negative impact on the environment; the use of methanol-based gasoline releases carcinogenic formaldehyde. Studies in China have shown that the higher the proportion of methanol in gasoline, the greater the amount of unburned formaldehyde emitted. Currently, automobile manufacturers in the United States, Europe, and Japan are firmly opposed to mixing methanol into gasoline. The World Fuel Specification issued in December 1998 stipulates that “the use of methanol is not permitted”” ； The new fuel specifications issued in April 2000 also explicitly stated again that \"the use of methanol is not permitted.\" Academic circles: There are opposing views. Theoretically, alternative energy sources can help reduce China’s heavy reliance on oil, but practical challenges related to their technology, performance, safety, environmental impact, and cost remain issues that cannot be ignored. There are differing opinions in the domestic academic community regarding whether methanol is suitable as a vehicle fuel, and the arguments of both sides have some merit. There are three main reasons in support of using methanol as a fuel for vehicles: it has a high octane rating. Methanol fuel is a liquid fuel whose physical and chemical properties are similar to those of gasoline and diesel; it is easy to use, has a high octane rating equivalent to that of 112-octane gasoline, and possesses a high latent heat of vaporization. Clean and environmentally friendly: Methanol fuel offers significant environmental benefits. According to analyses by the International Energy Agency and the U.S. Methanol Institute, the emissions of carbon monoxide, nitrogen oxides, hydrocarbons, etc., when methanol fuel is burned are lower than those produced by gasoline. The cost is low: 1 ton of methanol can be produced from 1.5 tons of standard coal, which gives it a significant cost advantage compared to 3.8 tons of standard coal per ton of oil produced by direct liquefaction, and 4.03 tons of standard coal per ton of oil produced by indirect liquefaction. If methanol is produced using cheap high-sulfur coal or the gas emitted during coking, the production cost is even lower. There are various reasons against using methanol as a vehicle fuel: the public is most concerned about safety issues, as methanol is highly toxic and difficult to eliminate once it enters the body. **The standards are becoming increasingly strict. The standard for lead-free gasoline for use in vehicles, which came into effect on September 1, 2004, stipulates that \"methanol must not be added artificially, and the detectable limit of methanol in lead-free gasoline for vehicle use is no more than 0.1%.\" It has its own drawbacks: methanol is corrosive and can cause swelling in the rubber components of vehicles. When not burned completely, it produces new pollutants such as formaldehyde. Additionally, factors such as its low calorific value and poor volatility at low temperatures also limit its use. Not recognized by neighboring areas – Methanol fuel is not used in the countries and regions surrounding our country. Once it is promoted for use in our country in the form of national standards, diplomatic consultations will be required. There is a discrepancy between the conditions under which vehicles are tested and their actual operating conditions. Vehicles tested with methanol-based gasoline are usually in good condition, but in reality, vehicle conditions vary widely; many vehicles are in poor condition, and the exhaust pollutants they emit are much higher than those indicated by the test results. Impact on conventional car engines: Some believe that long-term use of methanol-based gasoline will significantly shorten the interval between engine repairs. Furthermore, some believe that engines running on methanol gasoline have difficulty starting in cold weather during winter, and electrochemical corrosion occurs in the fuel system when the engine is left idle for long periods, requiring the fuel system to be cleaned – which increases operating costs. The promotion has not achieved the expected goals. Although methanol gasoline has been under testing for such a long time, there are still many issues that need to be resolved, such as safety hazards, distribution systems, and emissions. These issues were controversial in the past, and they remain controversial today. With disputes still existing over the key technical aspects, the effectiveness of large-scale promotion of methanol gasoline in the mainland provinces is indeed questionable. Widespread adoption poses difficulties for the refining industry. When developing methanol gasoline on a large scale, the ratio of diesel to gasoline must be taken into consideration. Data shows that the ratio of firewood to diesel used for consumption in our country is relatively high, and the demand for diesel is also substantial. Regarding the current amount of methanol added to gasoline, it is approximately 2 million tons per year, either explicitly or implicitly, and this replaces 1 million tons of gasoline; the impact of this on the ratio of diesel to gasoline in the refining industry is not very significant. However, if methanol gasoline is widely adopted and 20 million tons of methanol are used to replace 10 million tons of gasoline, the ratio of diesel to gasoline produced will reach 2.47 according to 2007 data; it remains uncertain whether our refining industry will be able to achieve this. If expanded further, with methanol gasoline doubling as well, the ratio of diesel to gasoline produced in refining will reach 3.10. If the refining industry cannot do it, what will happen to the remaining gasoline? Amid the calls to promote methanol gasoline, it seems no one has considered this issue. In 2007, China’s gasoline exports averaged 580,000 tons per month, amounting to an estimated 7 million tons for the whole year, which essentially covered the gap between production and consumption. If methanol is used to replace gasoline again, the surplus of gasoline will worsen, and only by increasing exports can this be compensated for. This industrial chain essentially involves using domestic or imported coal to produce methanol, replacing gasoline with methanol, and exporting the excess gasoline. In other words, the pollution generated by coal-based chemical industries is kept within the country, while efficient and clean gasoline is sold abroad. In 2003, the \"Strategic Study on Sustainable Oil and Gas Resources in China,\" led by the Chinese Academy of Engineering, was launched. The section on \"Research on Fuel Conservation and Alternative Fuels\" in the special report provided a preliminary summary of methanol gasoline. The report states that the use of methanol-based gasoline as a vehicle fuel declined by the late 1990s worldwide, mainly because methanol is toxic; it is difficult to prevent its toxicity during pipeline transportation and vehicle maintenance. From an environmental perspective, vehicles powered by methanol emit 3 to 6 times more formaldehyde than those using conventional gasoline... Practice has shown that the problems related to methanol’s swelling properties, corrosiveness, and toxicity still need to be addressed. If 100% methanol or gasoline containing 85% methanol is used as fuel, specialized engines, a complete set of storage, transportation, and sales equipment, as well as a reliable safety protection system are required. Compromise solution: MTG to replace methanol gasoline. At present, the actual use of methanol gasoline in China is rather chaotic, with a lack of corresponding **standards**. To promote methanol gasoline, standards must first be established. Many people believe that solving this problem is simple; once **standards** are established, methanol fuel can be used. In fact, this is not the case; when establishing methanol standards, it is necessary to reach a clear conclusion proving that the benefits outweigh the drawbacks. **The standards for ethanol-blended gasoline that have been established (the standards for ethanol-blended gasoline used in domestic vehicles) are basically based on the standards for lead-free gasoline. In other words, standards are easy to establish, but it is very difficult to draw a conclusion regarding the issue of methanol-blended gasoline. Therefore, we should not take only the advantages without considering the disadvantages. We can adopt a different way of thinking and use a compromise solution: improve the coal-to-methanol and methanol-to-gasoline (MTG) processes, add gasoline to the fuel tanks, leave the engines unchanged, and keep the exhaust emissions as they are. Wouldn’t that solve the problem? Tens of millions of tons of methanol now have a market outlet; the parties involved in the debate can reach an agreement – this is actually the best solution. MTG has extensive international experience, as well as research results that are nearly at an industrial level in China; demonstration plants are currently under construction, so promoting MTG is not a difficult task. The MTG process is one of the processes for producing hydrocarbons from methanol; it represents one of the main approaches in future methanol-based chemical manufacturing, and it is also one of the three routes for synthesizing oils (the other two being Fischer-Tropsch synthesis for diesel and coal liquefaction for diesel). Regarding the cost issue in MTG, it is certain that methanol cannot be purchased to produce gasoline; rather, it is an extension of the methanol production chain operated by coal companies. Based on a coal cost of 400 yuan per ton, the cost of methanol is 1600 yuan per ton. The cost of methanol as a raw material for gasoline is 4000 yuan per ton, with additional processing costs of 800 yuan per ton; thus, the overall cost of gasoline is around 4800 yuan per ton, allowing it to be sold on the market. Some might argue that the use of the MTG process reduces the energy efficiency of coal, and that a certain amount of energy is consumed in converting methanol into gasoline. It’s a fact, but the cost is worth it because we can avoid a lot of trouble. With the improvement of the MTG process, particularly through the use of second-generation MTG catalysts, the energy consumption of MTG will decrease significantly, and the energy utilization efficiency will improve markedly. The process for producing methanol from coal is already mature, so the reduction in energy consumption will not be significant. Therefore, we are convinced that replacing methanol gasoline with MTG is a good solution. Dimethyl ether: An objective analysis of advantages and disadvantages. Dimethyl ether is an important green industrial product; its main uses in the past have included applications as an aerosol propellant, a refrigerant, a foaming agent, and a raw material for organic synthesis. In recent years, due to its combustion properties being similar to those of LPG, dimethyl ether has been seen as a potential alternative to LPG as a fuel for household use, as well as a additive for diesel. Therefore, dimethyl ether has become one of the main types of alcohol-ether fuels. A proper understanding of dimethyl ether as a fuel: As an alternative fuel, dimethyl ether is said to have the following advantages: it is highly flammable, easy to compress, and safer. It can be mixed into city gas or natural gas for use in regulating supply levels, and it can improve the quality of gas while increasing its calorific value. The cost of producing it on a large scale is lower than that of diesel, propane, and compressed natural gas. This product was once very popular; around 60 units are currently under construction. However, the promotion of dimethyl ether at present is somewhat exaggerated; dimethyl ether fuel also has many disadvantages, mainly as follows: it requires high standards for engine design, and vehicles that use dimethyl ether must have their engines modified. The rubber sealing ring of the cylinder valve used for liquefied gas is prone to corrosion by dimethyl ether, resulting in leaks. Dimethyl ether has a relatively high latent heat of vaporization; if used as pure bottled fuel for household use, its combustion is unstable and this reduces its usable lifespan. Some researchers and economists, in order to promote the advantages of dimethyl ether as a fuel, claim that it can be produced from CO2. They do not understand that the purpose of the research project on producing dimethyl ether through CO2 hydrogenation is to address the issues related to the catalytic process and the composition of the product gas in the one-step production of dimethyl ether; they mistakenly believe that this approach can serve as a standard method for producing dimethyl ether. Therefore, they proposed using the results of this project for the production of dimethyl ether. Such propaganda has disrupted the formulation of dimethyl ether production policies. The development of this industry has encountered setbacks. Dimethyl ether, which was once seen as a potential alternative fuel, cannot be used in liquefied gas due to a ban imposed by the General Administration of Quality Supervision, Inspection and Quarantine; this will have an impact on the development of dimethyl ether. This document states that the use of dimethyl ether, as well as mixed fuels consisting of dimethyl ether and LPG, should be done with dedicated gases, dedicated cylinders, and dedicated equipment. The document does not prohibit the mixing of dimethyl ether into LPG; rather, it forbids adding dimethyl ether to steel cylinders containing LPG. Currently, dimethyl ether is facing severe setbacks as an alternative fuel. In 2008, China’s total capacity for the large-scale production of dimethyl ether exceeded 4.8 million tons per year. In 2007 alone, dimethyl ether projects with production capacities of millions of tons were put into operation. Currently, most facilities struggle to operate properly, with an average operational rate of less than 50%. The dimethyl ether industry is characterized by large production capacity and low output. In fact, solving the problem with dimethyl ether is very simple, just like the case with methanol-based gasoline. Dimethyl ether is an intermediate in the process of converting methanol into gasoline; therefore, as long as the processes for producing methanol from coal and converting methanol into gasoline (MTG) are optimized, or if dimethyl ether is directly used to produce gasoline with some LPG as a by-product, the problem can be solved. Ethanol: The source of raw materials is crucial. This traditional product, after being neglected for over half a century, has once again become the subject of intensive research and development since the 1990s. The reason for this is that, in an era when the world is facing an energy crisis, there is growing interest in utilizing ethanol as a fuel source. Our country faces a shortage of liquid fuels, and with the development and use of ethanol-blended fuels, the ethanol market will become even larger. Promoting the use of ethanol-blended gasoline in vehicles is one of our strategic initiatives, which fully reflects our determination to adjust the energy structure and address environmental pollution. Analysis of the advantages and disadvantages of ethanol fuel: The advantage of ethanol as a liquid fuel is that it enables more complete oxidation of gasoline, thereby achieving energy savings and environmental protection ； Ethanol has excellent anti-knock properties and can effectively improve the anti-knock capacity (octane rating) of gasoline; it can be used as an additive in lead-free gasoline to replace tetraethyl lead ； The greatest advantage of using ethanol-blended gasoline is reducing vehicle exhaust pollution, as well as other harmful substances in the exhaust gases. The disadvantage of ethanol as a liquid fuel is that, when it is used in combination with other fuels, some emission pollutants are reduced, but others such as acetaldehyde diethyl acetal increase significantly ； Ethanol has a low calorific value, so its consumption increases ； It causes swelling in rubber components of vehicles and corrosion in metal components ； Not suitable for long-term storage ； The fuel system and fuel tank must be thoroughly cleaned when the vehicle is used with ethanol-blended gasoline for the first time ； Not suitable for military special needs, **, and special reserves. Due to the aforementioned drawbacks, the trial use of ethanol fuel in pilot cities has not been satisfactory. Widespread use depends on technological progress. The issues associated with ethanol-blended gasoline are different from those of methanol and dimethyl ether; the advantages in terms of environmental protection and safety outweigh the disadvantages. The key issue lies in how to obtain ethanol. The main methods for producing ethanol currently include fermentation of agricultural products such as grains and sucrose, the ethylene hydration method, and direct synthesis from syngas. For a long time, the raw materials used for producing ethanol through fermentation were mainly sugar crops such as sugarcane, beet, and sorghum, as well as starch crops such as cassava, potatoes, and corn. Since these sugars and starches are also essential substances for our lives, using them to produce large amounts of ethanol as fuel will obviously affect human food sources. In recent years, to address the issue of excessive mold growth in old grain stocks, our country has proposed using part of this grain to produce ethanol, which can temporarily alleviate the conflict between an excess of grain and a shortage of fuel. However, our country is a large nation with a population of 1.3 billion; the issue of food is the top priority for the national economy, while the fuel issue comes in second. Turning food into fuel is not a viable solution. To this end, researchers have begun exploring the use of straw to produce ethanol, by hydrolyzing the straw with enzymes into monosaccharides and then fermenting them into ethanol. This process has not yet been used for large-scale production worldwide, mainly because the cost of enzymes is too high, rendering ethanol uncompetitive. In China, research institutions conducted pilot tests on using corn cob cores to produce ethanol, and these tests were successful; however, due to high costs, this process was not put into practical use. Furthermore, the high cost of collecting straw is also a difficult problem to solve. However, in the long term, using agricultural and forestry fiber waste to produce ethanol remains a very attractive approach; many countries around the world are conducting research in this area. Yet to date, we are still unable to use fermentation to produce ethanol as a solution for vehicle fuel needs. Synthesis methods: There are two ways to synthesize ethanol: producing it through the hydration of ethylene and producing it from syngas. The former is completely unfeasible, as ethylene has to be obtained from oil ； The latter refers to the synthesis of ethanol from syngas or CO2+H2; this can be achieved starting from coal chemical processes, but it has not yet been industrialized either domestically or internationally. The reason is that the process routes for synthesizing ethanol are not yet perfect, and the economic metrics do not reach levels competitive with those of other methods. In the mid-1980s, there were such scientific research achievements in China that received some publicity at the time, but industrialization never took place; the reason was that the process using rhodium catalysts for ethanol production had low efficiency, and the cost of these catalysts was too high. Currently, there is very little research on this process; it remains limited to the development of catalysts, and industrialization is still a long way off. There are no signs that this approach will necessarily succeed. 　　 The practices in the refining industry are worth considering. The enthusiasm for promoting methanol gasoline in China stems from some scholars in the fields of chemistry and economics; their intentions may be good, as they aim to help address issues related to alternative fuels and economic development. But this is a national issue, and practices from the refining industry should also be studied. The refining industry has a different perspective on alcohol-ether fuels compared to the chemical industry; when it comes to gasoline additives, they focus primarily on the oxygen content in gasoline. The traditional practice in the refining industry is to reduce emissions for environmental reasons, by controlling the oxygen content in gasoline to no more than 2.7%. Thus, the maximum contents of oxygenated compounds in gasoline are: 5.4% for methanol, 7.76% for ethanol, and 14.85% for MTBE. Recently, the new formula gasoline (RFG) in the United States has reduced oxygenates to 2% by weight. Based on this, the maximum allowable content of oxygenated compounds in the gasoline is as follows: the proportion of ethanol will be reduced to 5.75%, while the proportion of methanol will be reduced to 4%. **The addition of ethanol to gasoline has been approved; gasoline purchased in the Northeast is of grades such as E10-90 and E10-93, which means that 10% industrial ethanol is mixed into the gasoline. Since the calorific value of ethanol is lower than that of gasoline, the driving range is affected. Currently, the addition of methanol to gasoline is strictly prohibited in the United States, Europe, China**, and Taiwan. Some provinces in our country are still promoting methanol-based gasoline, such as M15; this not only poses a hazard to drivers but also significantly reduces the driving range of vehicles and causes corrosion of mechanical equipment, which goes against the traditional practices of the refining industry. 　　 Market volatility curbs the overheating in alkoxy ethers. In recent years, China’s methanol production has been on the rise, with an increasingly fast growth rate. Since last year, methanol production has continued to rise, but at a slower pace; it has not managed to achieve an annual increase of 40%, with the growth rate remaining below 20%. Affected by the international financial crisis, over 40% of alcohol ether manufacturers have ceased production at present; the vast majority of such production facilities are operating at reduced capacity, resulting in a continuous decline in output and supply, which will help alleviate the situation of oversupply and the associated sales pressures. In 2008, the production of methanol fell short of the expected 14 million tons, reaching only 11.26 million tons. Furthermore, the sharp drop in the prices of liquefied petroleum gas and natural gas in the international market has also exacerbated the supply-demand imbalance of alcohols and ethers in the domestic market. Since the price of natural gas in regions such as the Middle East is only 0.57 yuan per cubic meter, which is far lower than the price of natural gas used for methanol production in China, which is over 1.5 yuan per cubic meter, and given that the scale of these facilities often reaches millions of tons, they possess a clear advantage in terms of cost, technology, and scale. As international markets saw a decline in demand due to the global economic recession, cheap methanol from regions such as the Middle East flowed into China, a market that still maintains stable economic growth and has high demand, thereby exacerbating the supply and demand imbalance for alcohols and ethers in the country. Recently, the CIF price of methanol from regions such as the Middle East has been as low as 1,900 yuan per ton, and the supply is abundant. As a result, downstream users of methanol in eastern and southern China have significantly reduced their purchases of methanol from the central and western parts of the country. Many methanol manufacturers have seen an increase in their inventory levels, forcing them to continuously lower their export prices. It is currently impossible to predict to what extent the impact of this financial crisis will extend. However, the situation of alcohol ether superheating that we have observed is already easing. 　　 The development of alcohol-ether fuels is slowing down. In summary, the issues related to alcohol-ether fuels represent a significant challenge; although methanol, dimethyl ether, and ethanol all show promise as alternatives to conventional fuel for vehicles, none of them have been fully successful in China to date. All are still in the experimental stage, and the results so far are not satisfactory. Among them, ethanol fuel is the closest to achieving the goal, but it still has not achieved it. These three types of fuel each have their own difficulties. Methanol fuel is the most difficult to adopt, and it’s hard to change this situation due to its daunting toxicity issues. The fundamental disagreement among all parties regarding methanol gasoline lies in environmental protection; other issues can be negotiated. The process of methanol gasoline being actively promoted abroad and then gradually phased out shows that people’s awareness of environmental protection is constantly improving. Dimethyl ether is a decent additive for diesel as a vehicle fuel, but it requires modifications to existing vehicle engines and related components, resulting in significantly increased operational costs; as a household fuel, it is inferior to LPG. Ethanol fuel has successful precedents abroad, and we can achieve success as well. But in China, its source poses problems; it cannot be obtained through grain-based methods. Although cellulose fermentation is a good approach, its large-scale use still depends on scientific progress. In fact, using the MTG method to produce gasoline from methanol as a substitute for methanol and dimethyl ether fuels is not only a way to address the problem at its source but also feasible for large-scale industrial implementation. Replacing methanol gasoline with MTG is a strategy with more advantages than disadvantages, and the path ahead is promising. However, it is also necessary to pay attention to coordinating with F-T synthesis in order to maintain a reasonable fuel-to-gas ratio. Given the recent introduction of the second West-to-East Gas Pipeline to address the fuel shortage in southern regions, the importance of alcohol-ether fuels is declining. To address the issue of alternative fuels, safety and the environment must remain the top priorities. Solving the issue of alternative energy through chemical methods requires scientific thinking and proper approaches; the development of alcohol-ether fuels should be slowed down!