Coal-to-natural gas has advantages in terms of water and energy consumption
Thread Content
Currently, in China, the methods for converting coal into energy products include power generation, coal-to-oil conversion, coal-to-methanol and dimethyl ether production, and coal-to-natural gas production. The energy efficiency, from lowest to highest, is as follows: coal-to-oil (34.8%), coal-to-dimethyl ether (37.9%), coal-to-methanol (41.8%), power generation (45%), and coal-to-natural gas (50%–52%). Coal-to-gas has the highest energy efficiency; it is the most effective way to utilize coal, as well as the optimal method for producing coal-based energy products. In terms of water consumption per unit heat value, the water usage per gigajoule ranges from lowest to highest as follows: coal-to-natural gas (0.18–0.23 tons), coal-to-oil (0.38 tons), coal-to-dimethyl ether (0.77 tons), and coal-to-methanol (0.78 tons). Coal-based natural gas has the lowest water consumption per unit of heat value, making it the most water-efficient energy product; this is of great significance for the development of the coal chemical industry in western regions where coal is abundant but water is scarce. Since the methanation unit for coal-to-natural gas produces a large amount of high-pressure steam, this steam is used to drive the air separation turbine, reducing the use of boilers and fuel coal. In the methanation unit, almost 84% of the waste heat is recovered in the form of high-pressure steam, while only 0.5% of the waste heat needs to be cooled using cooling water; thus, the heat recovery efficiency of the entire system is very high. At the same time, a large amount of excess low-pressure steam can be used for power generation. In coal-based methanol, dimethyl ether, and synthetic oil plants, almost all of the high-pressure steam required for air separation is supplied by boilers, with virtually no excess low-pressure steam available. To this end, coal-to-natural gas can **reduce CO2 emissions from boilers and power generation**. For example, in coal-to-natural gas projects that use water-coal slurry gasification technology, the production capacity is 1.6 billion cubic meters of natural gas per year; the excess low-pressure steam is used for power generation, producing 480 million kWh of electricity annually, which is equivalent to a reduction of 451,200 tons of CO2 emissions ； This project generates 542 tons per hour of steam at 9.8 MPa as a by-product of methanation, resulting in an annual reduction of 1.38 million tons of CO2 emissions.
In early February 2009, the production facility for manufacturing 3,000 tons of carbon dioxide-degradable plastics per year, funded by CNOOC Investment Holdings Co., Ltd., was successfully commissioned and began producing qualified products. The total investment in this project was 152 million yuan, and construction began in July 2007. The project utilizes world-leading patented technology independently developed by the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, with CNOOC Chemical Co., Ltd. being entrusted with the project construction and production operation management. The project makes full use of the resources such as water, electricity, and steam available from the existing facilities in the Dongfang Industrial Park, using the carbon dioxide emitted by these facilities as raw material. Yang Yexin, CEO and President of CNOOC Chemical, said that the successful implementation of this project will enable the direct reduction of 2,100 tons of carbon dioxide per year, helping to achieve the energy-saving and emission-reduction goals set forth, while also eliminating \"white pollution\" and contributing to the development of Hainan as an ecological province. It is reported that environmentally friendly plastic bags made from carbon dioxide-degradable plastics are a first both in China and internationally, representing a breakthrough in the resource-based chemical industry. It is understood that producing 1 ton of plastic for this project requires 0.5 tons of carbon dioxide, with the output value per ton being around 20,000 yuan. To date, CNOOC has identified natural gas reserves of around 2 trillion cubic meters in the Yinggehai Basin in the South China Sea, where the project is located (70% of these reserves contain carbon dioxide). If production scale is expanded, it will significantly reduce the concentrated emission of carbon dioxide from an environmental perspective; it can also replace polluting, non-degradable plastics, thereby creating a more rational and efficient industrial chain that allows for the utilization of by-product waste gases, achieving a \"win-win\" situation in terms of economic benefits and environmental protection.
Reporters learned from departments such as the Economic Commission of Inner Mongolia Autonomous Region that, in order to adapt to the conditions in the coal market and raise the level of the coal industry, Inner Mongolia will exercise appropriate control over coal production in 2009, while further optimizing the capacity structure of the coal industry. Under the newly introduced plan, Inner Mongolia requires the coal industry to moderately control raw coal production based on the market supply and demand conditions in 2009. In addition to projects for on-site coal conversion, this year Inner Mongolia will focus on advancing the construction of approved and ongoing coal projects, accelerating the integration and technological upgrading efforts in the coal industry, and will not approve any new coal construction projects. In 2009, Inner Mongolia initially planned to produce 470 million tons of raw coal throughout the year, with the intention of keeping the additional production capacity resulting from technological upgrades and new coal projects within 100 million tons. At the same time, Inner Mongolia will continue to consolidate and shut down small coal mines with an annual production capacity of less than 300,000 tons, striving to close at least 30 such mines throughout the year in order to achieve the goal of phasing out 4.78 million tons of outdated coal production capacity by the end of the year. At the same time, this year Inner Mongolia also plans to phase out another 3.9 million tons of outdated coke production capacity. Furthermore, in order to enhance the overall competitiveness of the coal industry, in 2009 Inner Mongolia also pursued an integrated development strategy that covered coal, electricity, chemicals, transportation, and ports. It further liberalized the coal trading market and abolished local policies such as coal sales permits, thereby making coal prices more market-driven. Inner Mongolia will also support power companies in accelerating the development of their own coal resources, with the goal of achieving a coal self-sufficiency rate of over 50% for power generation enterprises by 2010. As one of China’s largest coal-producing regions, Inner Mongolia’s coal production in 2008 reached 457 million tons, representing a net increase of about 107 million tons compared to the previous year.
The methanation process in coal-to-natural gas production generates some water; by flashing to remove the small amount of gases present, this water can be reused, and some excess water is produced in this stage. However, water is still essential for vaporization, and this is the largest contributor to water consumption.
Water consumption in coal chemical industry falls into two main categories: one is the water required for reaction conversion, as this water participates in the reactions, and this is a very prominent feature of coal chemical processing； The second is the process water required in production; this water does not participate in the reaction. For engineering water use, it is necessary to conduct actual calculations based on the existing coal chemical plants (regardless of whether their products are natural gas, oil, or methanol) in order to have a meaningful comparison. The water involved in the reaction primarily provides hydrogen; the higher the H/C ratio in the product, the more water is consumed. This post was last edited by *aojungnft on 2009-2-13 17:05]
Before the New Year, due to price differences, the five major power companies failed to sign a single contract with coal companies. After the New Year, a turning point finally emerged in the struggle between coal power and alternative energy sources. Reports suggest that power plants under China Huaneng and State Power Investment Group have signed contracts worth over one million tons with Shandong Zikang Group. Of this, 240,000 tons were contracted with Huadian, and 900,000 tons were contracted with Guodian. In addition, Huaneng Group is also actively in contact with Shandong Zikang Group, with plans to purchase 4 million tons. Industry insiders, in interviews with journalists, generally believe that this marks the beginning of the signing of coal power contracts in 2009, and more contracts are likely to be signed between coal producers and power companies in the future. In 2008, the thermal power industry found itself in the awkward situation of suffering losses across the board. Due to the soaring coal prices, the total losses of the five major power companies amounted to around 40 billion yuan. To avoid suffering further losses, the five major power companies adopted a united stance of resistance to the coal companies’ requests for higher prices for contracted coal. “The meeting on coordinating coal production, transportation, and demand in 2009 ended unhappily as expected, but recent developments suggest that the contract negotiations between coal producers and power generators for 2009 have resulted in an agreement. ”An anonymous coal industry analyst said this in an interview with reporters. In his view, this marked the beginning of the signing of coal power contracts in 2009. At present, coal used for electricity accounts for 53.65% of China’s total annual coal consumption, and the five major power groups consume over 50% of that amount – which gives them sufficient leverage in negotiating the prices of coal contracts. Last year, based on their assessment that there would be an oversupply of coal in 2009, the five major power companies firmly rejected requests for an increase in the price of thermal coal, insisting instead on a reduction of 50 yuan per ton in the prices specified in the coal supply contracts. However, coal companies also face their own difficulties: they are asking for a price increase of 50 yuan per ton for key contract coal, on the grounds of an increase in value-added tax and a shift from a volume-based to a value-based system for resource taxes; the revised price would be 550 yuan per ton. There is a price difference of 100 to 150 yuan between the quotes offered by power companies and coal enterprises. The deadlock between the two sides resulted in the five major power companies failing to sign any coal contracts at the \"2009 Coal Ordering Conference.\" However, in the face of the reasons given by both coal-fired power producers and electricity companies, **the National Development and Reform Commission did not intervene immediately, but had to wait for more favorable circumstances to arise. Although no intervention was carried out, according to reporters, following this coal ordering conference, coal companies began to implement production restrictions in an effort to maintain stable coal prices and put pressure on power companies. However, after the Spring Festival, some coal companies relaxed their production restrictions. A relevant official from Shandong Zikuang Group, which has signed contracts with power plants under Huadian and State Power Investment Corporation, said, “The company has started to work overtime to increase production.” In fact, regarding the contradictions that have arisen in the negotiations over thermal coal, the Energy Bureau also issued a clear statement at the recently concluded National Energy Work Conference: it is reasonable for coal companies to demand price increases, but given that the domestic economy is under the impact of the financial crisis, it is not appropriate to raise electricity prices at this time. The current conflict over coal-fired power generation reflects the fact that electricity prices have not been properly regulated. However, since both coal and power generation enterprises are state-owned, they should put the overall interests first and resolve these issues properly. **The Energy Bureau’s statement is seen by the industry as a way of signaling to the outside world that it is supporting coal companies, and it is precisely this support that has been a key factor in breaking the deadlock in the negotiations over coal supply contracts that had been stalled for months. (Reporter Zhu Baochen)