Power plants, conventional coal-fired

In February 2007, the UN Intergovernmental Panel on Climate recommended banning the construction of all conventional coal-fired power plants. 

Coal Conventional Coal-fired Power Plant NG Advanced Namral Gas Power Planl DC Direct Combustion... 

Empirical experience with conventional coal-fired power plants has indicated minerals containing alkali metal (Na, K), sulfur- and chlorine-bearing species to be the most aggressive fuel components leading to fire-side or hot corrosion (5). 

The capital cost of STPs is one quarter to a half of that of PV power plant (Table 1). The LEC is defined by the total cost, [(capital cost)x(fixed charge rate) + O M + fuel cost], per annual net electricity production in kWh. It varies depending on the plant scale and solar share. The LEC ranges between 0.05kWh and 0.12/kWh for the STP, and attains 0.4/kWh- l/kWh for PV electricity. Thus, the solar H2 production cost by PV and STP electricity is not comparable in terms of capital cost and LEC. However, the cost of STP electricity is still not competitive with that of a conventional coal-fired power plant. To close the price gap, the solar thermal parabohc trough power plant industry has introduced integrated solar combined cycle systems (ISCCS) which are able to offer a competitive base-load electricity cost of 0.05-0.07/kWh at solar shares of 15-25% [7] (Fig.l). 

In addition to carbon sequestration, technologies that would provide economic benefits include those that enhance oil recovery, produce coalbed methane, and maintain pressures in depleted gas reservoirs to avoid surface subsidence. Currently, companies in the United States sell one billion standard cubic feet of C02 each day, or approximately the C02 output from one conventional coal-fired electric power plant with a power capacity of 2300 MW. This C02 is used economically and with little or no environmental impact for approximately 70 enhanced oil recovery projects and for other industrial applications. Pipeline specifications for C02 quality, pipeline safety issues, and custody of the C02 have a base of industrial experience that goes back to the 1970s. Today, there are operating C02 pipelines of up to 760 mm (30 inches) in diameter and 640 km (400 miles) in length (Fig. 6-6). 

No form of energy production is without risk. Make a list of the risks to society involved in fueling and operating a conventional coal-fired electric power plant, and compare them with the risks of fueling and operating a nuclear fission-powered electric plant. 

The world production of coal is projected to rise from 2772 Mtoe in 2004 to 2818 Mtoe in 2010 and 3779 Mtoe in 2030. Much of this coal will be used for electricity generation. In future, rather than employing conventional boilers, coal will probably be converted to a gaseous fuel that will power gas turbines as part of an IGCC scheme. Compared with conventional power plants that are fired with pulverized coal, IGCC offers the following advantages ... 

Figure 51.24 shows a schematic of a steam-fluidized bed dryer with combined generation of power and heat. In a conventional coal-fired power plant, up to two-thirds of fuel energy is lost since the latent heat of turbine exhaust steam is dissipated unused to the cooling water because of its low-temperature level. In the DWT process, the latent heat can be used to dry the input coal. Figure 51.24 shows a coal-fired... 

Natural-gas-fueled steam electric power. Natural gas can substitute for coal in conventional coal-fired electric plants. The capital cost is estimated at 780/KW (design capacity) and O M at 2.6% of plant irrvestment. 

The United States Department of Energy sponsors many research projects, particularly into next-generation pressurized fluid bed combustion combined-cycle power plants. The goal is to design plants with a net system efficiency of more than 50 percent, extremely low sulfur and nitrogen oxide emissions well below 2010 emission limits, and at a power-generation cost of three-quarters by a conventional coal-fired power plant. The European Union similarly sponsors research in this area, as does Japan and other developed or developing countries. 

Coal gasification plants have two principal sources of water effluents which are similar to those in conventional coal-fired power plants. The first source is wastewater from the steam cycle, including blowdowns from the boiler feedwater purification system and the cooling tower. The amount of this wastewater effluent depends on the hardness of the original raw water feed to the plant and the size of the steam cycle. 

An IGCC plant generally produces fewer water effluents than a conventional coal-fired power plant does. The amount of process water blowdown is about the same for both gasification and direct coal combustion. However, the steam cycle in IGCC power plants produces much smaller amounts of wastewater blowdown because less than 40% of the total power generated comes from the steam cycle. 

Modification of direct coal combustion for CO2 removal would be more difficult. CO2 could be removed from the flue gas after conventional combustion by acid gas removal technology. Although this approach has found some commercial application, the low pressure and low concentration of the CO2 in the flue gas makes it a relatively expensive method. Removing 90% of the CO2 from flue gas of a conventional coal-fired boiler would increase the capital cost by a factor of 3.0 and thermal efficiency drops by 12% compared to a conventional direct coal combustion power plant. The larger capital increase and efficiency loss with CO2 recovery is principally due to recovery at low pressure which requires a larger flue gas compression, CO2 absorbers, and increased steam requirements. Depending on the cost of coal and capital, the increased electric cost for CO2 removal with a direct coal combustion power plant is 2.0-3.0 times that of a conventional direct coal combustion power plant. 

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