Global Resources: Energy
The Trend of Power Technical Development
By Henry H.J. Lin
The use of fossil fuel improves modern human life and increases economic development. However, the use of fossil fuel also impacts the ecosystem and introduces severe environmental pollution. According to an article published in Times Magazine issued on September 2002, the water temperature of the Arctic is 4 °C higher than that of 1972 and a resulting 40% decrease in glacier presence. The phenomenon mentioned above has mainly been caused the heavy use of fossil fuels and the co-production of carbon dioxide leading to the global greenhouse effect. Scientists have warned that the Arctic will be completely melted by 2050 if this situation continues. At that time, the climate of the earth will be changed significantly, and all living things will face a crucial test for survival. Meanwhile, we will face the shortage of energy. In 1996 Energy Magazine predicted that the petroleum reserves has an expectancy of only 45 more years, while all natural gas will be expended in 65 years, and coal in 228 years. The recent rise in petroleum prices is mainly due to the oil-exporting countries reluctance to expend their oil deposits at the current rate.
Because of many problems caused by using fossil fuel, such as air pollution, scarce petroleum deposits, the difficulty of handling nuclear power waste, and uneconomic secondary energy development, we have to become well aware of the trend of power technical development. Therefore, the important technical trend is as follows: the increase the efficiency of energy consumption, the decrease of air pollution, and the prevention of investment waste. The technical trend in this paper is focused on four main subjects: techniques for decreasing air pollution, the enhancement of energy consumption efficiency, the development of clean power generation, and methods of secondary energy development.1. Decreasing air pollution
1-1 . Decreasing Sulfide Oxides (SOx)
The primary methods for eliminating sulfide from 'stack gas' are the 'wet' method, the 'dry' method, the 'wet absorbent injection' method, the 'dry absorbent injection' method, and the 'seawater elimination' method. In addition to these methods, for older facilities which may use low sulfur content fuels to decrease pollution, coal is actually more economical compared to the use of relatively expensive sulfur-eliminating equipment. Among all of the sulfur control methods, the most efficient methods are the wet method and the seawater eliminating method. However, although the seawater eliminating method represents a lower investment, the follow-up problems of seawater PH control and waste treatment are substantial, thus the developed countries are not willing to adopt this method. As a result, the wet-type Sulfur control method is prevalently used.
1-2. Decreasing Nitride Oxides (NOx)
The methods for reducing Nitride Oxides concentration include the LNB (Low NOx Burner), SCR (Selective Catalyst Reduction), and SNCR (Selective Non-Catalyst Reduction). In addition to its higher investment cost of, SCR also presents follow-up waste treatment problem, hence the LNB is the choice of most users. Consequently, the LNB operated in coordination with improved burning methods is currently of the highest interest. By using the LNB, NOx concentrations can be limited to less than 10 ppm, and with the use of burners, this can be further reduced by as much as 60%. The most important factor is how to optimize the fuel-gas ratio and burning temperature. For SNCR the most important criterion is the temperature control at the nitrogen injection zone. If the temperature is too high, NO will be synthesized; on the other hand if the temperature is too low, nitrogen will be released due to non-reaction. Generally, if the reaction temperature is controlled between 900°C and 1100°C, the elimination rate will be around 40% to 60%.
1-3 . Decreasing Carbon Dioxide (CO2)
The means of removing CO2 include CO2 separation and catalyst-hydrogen reforming and biologic/physical solidification. With the exception of Catalyst-hydrogen reforming with proven economic value, other means are currently undergoing laboratory testing. In the US, coal fire co-generation and gas fire co-generation using the CO2 separation is already in commercial operation. In the future, CO2 reduction will be necessary and will become a mainstream technology.
2. Technique for enhancing utilization rate
2-1. Supercritical Boiler
Thanks to material science, the supercritical boiler will become a trend due to its high efficiency and steady material temperature. With the exception of units with steam pressure of 300 bar, a temperature of 620℃, with 45% efficiency which began operations commercially in 2000, it is foreseeable to have a unit with a steam pressure of 325 bar, a steam temperature of 700℃, and 55% efficiency by 2020. Whether a coal fire or LNG fire unit, a supercritical boiler is the best solution for reducing air pollution with a lowered investment cost.
2-2. Combined Cycle
To increase the utilization rate of the expensive LNG, a single unit at 38% efficiency and a combined unit at 58% efficiency, combined cycle units (gas turbine, HRSG and steam turbine) have successfully entered the market. Due to the advantages of the greenhouse effect and lesser emissions, the combined cycle could become the mainstream thermal unit, especially in LNG producing countries.2-3. Advance Cheng Cycle
The Advance Cheng Cycle was invented by Chinese. With this method, the steam produced by HRSG is injected into a gas turbine, thereby increasing efficiency to 42% and reducing the investment for phase II (steam turbine and condenser system). The only disadvantage of this method is its high consumption of water. This method has competitive advantages for units below 100 MW, and 50 units are currently in commercial operation worldwide.
3. Technology for Clean Energy
3-1. IGCC (Integrate Gasification Combined Cycle)
IGCC uses the technology of transferring coal or fuel oil into syngas which consist of CO, H2 or CH4; the syngas is then sent to the combined cycle unit for power generation after removal of dust, SOx and NOx. This method can achieve an efficiency up to 43.5%. At least 20 units of coal firing, petro coke firing, and bottom oil firing with capacity from 40 MW to 550 MW (Texaco fuel gas boiler combined with Siemens V94.2 and GE S109E gas turbine) currently operate commercially since the first 120 MW unit began operations in 1984. The required fuel can be either high-sulphur or high metal fuel. Due to the high price of syngas ($5.6/MBTU compared with $2.75/MBTU for LNG), it is appropriate for low-grade fuel to generate power. Thanks to the development of material technology achieved in the gas turbine, the supercritical boiler, and the shortage of LNG, the IGCC method could be a star performer in the future.
3-2. Fluidize Bed Boiler
The fluidize bed boiler is equipped with a furnace bed for the burning of lower grade coal (high sulphur, low heating value), and bio fuel (wood chips, wood block, trash). Low-grade coal could mix with limestone and desulphuring additives as liquid fuel to reduce air pollution and improve efficiency with a chemical reaction when burning. There are different fluidize bed boilers (CFB, IR-CFB, BFB, and PFBC) subject to different fuels, purposes, and manufacturers.
The CFB (Circulating Fluidize Bed) is most commonly used in incineration. Low-grade coal (high sulphur, low heating value), and bio fuel (wood chips, wood block, trash) can be the perfect fuel for CFB; generation capacity could be as high as 550 MW. IR-CFB collects unburned material in the bottom of the economizer and superheater and then sends the material into a furnace for re-burning to enhance its combustion efficiency. BFB is designed for bio fuel; a vent hole in the bottom of the boiler assists the complete combustion. As for the PFBC (Pressurize Fluid Bed), ABB Alstom’s products P200 and P800 are the most known within the marketplace. The P800 is an IGCC unit with an output of 350 MW. In summary, the FBB is more popular due to its features of low air pollution, high efficiency, and multi-use of lower-grade fuels.
4- Secondary Energy
4-1. Fuel Cell
The advantages of the fuel cell include low pollution, high efficiency (60%), and slim/light characteristics. However, due to high cost and short life, the application of the fuel cell is still under development. More attention will be focused upon this technology when the issues of CO2 reduction and continuing price increases for oil become more prevalent. In fact, among the already developed technologies, including AFC, PAFC, MCFC, SOFC, FEMFC and DMFC, only SOFC, PAFC, and MCFC are used within the power generation industry. The Energy Resource Department (ERD) of ITRI has imported 200 KW of PAFC fuel cells for a six-year run-test, but this test was given up due to its high cost of power generation (NT$8/kwh); ERD has changed its focus to new technology for fuel cells for automobiles and computers.
Some countries are putting their efforts into the investment and development for related technologies, including the application on small-sized steam turbines, solar energy, and hot water equipment. It is forecast that these developments can reduce pollution by the equivalent of 8 million tons of CO2 per year by 2010.
4-2. Wind Power
Wind Corp. of Denmark is the most authoritative manufacturer of wind power technology. Its V66 turbine contains 65 meters of blade surface area, and the capacity of a single unit is 750KW, at a distance of 80 meters from the ground. The unit can withstand hurricane-force winds of 131.1 mps, and boast a lifetime of 50 years. Wind power accounts for 15% of all power generation in Denmark. In order to increase power output and decrease land occupation requirements, Denmark and the Netherlands plan to develop a single sea-based 2MW unit in 2005. After the modularization of wind power, due to its reliability and low maintenance, more and more countries will come to rely on wind power. Under the appeal of former-president Clinton’s 'green power' generation, by 2020 wind power will account for 5% of all power generation in the United States and will reach at generation level 10,000 MW; by the same token, Texas will become the number one wind power city after its completion of a 2000 MW of wind power generation farm in 2009. As of 2001, installed wind power capacity rankings worldwide are 8753MW in Germany, 4261MW in the US, 3335 MW in Spain and 2417 MW in Denmark, followed by other nations of lower rankings. According to the European Wind Energy Association (EWEA) and the Green Peace Organization’s proposal "Wind Force 12" of May 2002, it is predicted that world wind power will reach 12% of total capacity in the year 2020.
Power is the mother of all industries. More and more, a country’s national strength could come to be evaluated by its power consumption. In the developed nations and the developing nations alike, as economic development increases, so will power consumption increase along with the increase of GNP, regardless how rich or how poor a country may be. However, the issues of environmental pollution, the greenhouse effect, and energy shortages come with the world's massive consumption of power. All nations must focus on the development of new power technology in order to decrease pollution, reduce the greenhouse effect, develop substitute energy sources, and enhance the efficiency of use of fossil fuel. From the above-mentioned introduction, the power industry must grasp relevant information and learn the trends of power development in order to reach the best solutions and determine the best allocations of resources. When giving full consideration to power co-generation and other aspects of the power industry, we must determine how we can effectively and sufficiently improve the utilization rate (which, in some case, a rate of 94% is attainable); as the situation currently stands, the average efficiency of pure power generation is around 35 %, and questions should be seriously asked about the continuation of this waste.
Modern Power System etc.
Power industry expert and BWW Society/IAPGS member Mr. Henry Lin Hai-Jui graduated from the Taipei Technical Institute with an MB degree in 1967, and later attended Sun Yat-Sen University. He is the recipient of the Top Ten Outstanding Engineers' Award, the CEA Taiwan and The Outstanding Schoolmates' Award, which was awarded to him by Taipei Technical University in 1999. Internationally recognized, Mr. Lin presented papers on power generation and the energy industry at the IPGC Conference Atlanta (1992), the Asia IPGC Conference in Singapore (1997 and 2002), and the ICQCC Conference in Taipei (2001). Additionally, Mr. Lin speaks five languages, including Mandarin, Taiwanese, Haka, English and Japanese.
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