Thermal Power Generating Plant – Impact
Ensult Limited undertook an environmental impact study on behalf of the town council and the residents of Greenopolis Town. The town council wants to construct a thermal power plant to generate 250 MW of power to meet the rising power demand. However, some of the locals opposed the idea on the basis that it will lead to environmental pollution and eventually it will lower the quality of life in Greenopolis. The decision to engage the services of Ensult came from the need to find an impartial consultant to study the investment plan. The consultant was to render an opinion on the environmental impacts of the proposed power plant.
The objectives of the study were as follows. First, Greenopolis tasked the consultants to analyze different sources of fuel for the thermal power plant and to recommend the best option for the town based on its needs. Secondly, Greenopolis wanted the consultants to compute the environmental costs of the plant.
The consultants used the following methods to collect the data used in the project. First, the consultants conducted interviews with key stakeholders to determine the concerns of the town regarding the new power plant. The interviews were conducted informally because the issues in question were already clear to all the parties involved. Secondly, the consultants reviewed literature from various sources touching on various aspects of power generation. It was necessary to clarify on the complete range of options available for thermal power generation. Thirdly, the consultant studied data provided by the Environmental Protection Agency on the costs and levels of emissions produced by various energy sources.
The consultants isolated the main issues regarding this project as follows. First, the town council is interested in securing the future power supply of Greenopolis based on future power demand projections. The current power supply cannot meet the future needs of the town. Secondly, the main concern of the residents is to preserve the environment so that Greenopolis remains a pleasant town to reside. Both parties were sympathetic to the objectives of their counterparts.
The consultants eliminated nuclear power as a source of energy for the proposed power plant. Nuclear energy is not a viable energy source for plants that generate below 3000 MW of electricity. Therefore, the main power sources that the consultants analyzed were coal, geothermal power, biomass pellets, and natural gas. The cost estimates used in the report are from the US Environmental Protection Agency (EPA). The figures represent the average cost of power generated by a plant averaged over the useful life of the plant. The figures consist of both capital and operational costs of the plant.
Coal is one of the oldest sources of energy. It is relatively easy to store and use. However, coal also has the reputation of being one of the sources of energy. Physical handling leaves black stains on surfaces, and its combustion produces fly ash and bottom ash in large quantities. It costs $90.1 to generate a megawatt of power using coal (EPA). Coal plants that do not have carbon capture technologies emit 1001 kg of carbon dioxide for every megawatt of power produced (EPA). Plants with carbon capture technologies emit 398 kg of carbon dioxide per megawatt of power generated.
Natural gas is used to generate thermal energy. Natural gas power plants came into existence once engineers developed combustion systems that could burn natural gas. The cost of power generated by natural gas plants ranges from $69-105, depending on the thermodynamic cycle used by the power plant (EPA). Natural gas power plants emit an average of 470 kg of carbon dioxide for every megawatt of power they generate (EPA). These plants have lower levels of ash, but they produce a greater quantity of greenhouse gases compared to solid and liquid fuels (Harris 34). The best mode of transport for natural gas is via pipelines.
Geothermal power comes from underground heat reservoirs. Hot rocks heat ground water, which then rises to the surface in the form of superheated steam. Engineers usually drill wells in sites with geothermal potential to channel the superheated steam to power generation plants. Theoretically, geothermal power does not pollute the environment because the only byproduct of power generation is water. However, the gases from these wells usually contain other compounds such as carbon dioxide, sulfur dioxide, and methane. The cost of producing one megawatt of electricity using geothermal power is $100 (EPA). In addition, a typical geothermal power plant will emit 45 kg of carbon dioxide for every megawatt of electricity it generates (EPA). The drilling of geothermal wells does not disturb the natural environment appreciably. However, the steam emitted from the plant alongside other gases can cause thermal and air pollution.
Biomass pellets are an emerging source of fuel for small power plants. The pellets are made from compressed biomass waste produced by food processing plants and by lumber yards. The pellets, also known as briquettes, make it possible to utilize compressed biomass as fuel (Greg, Simonton and Beruvides 44). The quantity of pellets required to operate a 250 MW plant makes this option impractical. The main environmental benefit of this option is that it uses waste materials to generate power. The materials used to make biomass pellets are usually disposed as waste.
On the other hand, the use of biomass pellets robs the soil of materials needed to replenish its nutrients. The pellets also may produce other gases (such as carbon dioxide and methane) during combustion, leading to global warming. Dealing with waste ash is also an environmental concern. The table below summarizes of the options that the consultants reviewed.
|Fuel Source||Cost per MW($)||Criteria Pollutants|
|CO2 (Kg/MW)||Other Greenhouse Gases||Other Wastes|
|Coal||90.1||1001||Methane, Sulfur Dioxide, NOX||Fly ash, Bottom Ash, Smog|
|Coal (With Carbon Capture)||90.1||398||Methane, Sulfur Dioxide, NOX|
|Natural Gas||69-105||470||Methane, Sulfur Dioxide, NOX||Smog|
|Geothermal Power||100||45||Methane, Sulfur Dioxide, NOX gas, Water Vapor, Hydrogen Sulfide, Ammonia||Arsenic, Boron, Smog|
Table 1: Cost of Power Production and Criteria Pollutants.
Based on the findings presented above, the consultants recommend that Greenopolis adopts geothermal power as its source of energy for the 250 MW plant. The following reasons underlie the recommendation. First, geothermal power is available locally. The town will not need supplies from other regions to run its power plant. The power will also be available continually without interruption caused by supply chain concerns. Secondly, geothermal power offers the best environmental protection and conservation opportunities for the town (Duffey and Dorp 28). It is possible to construct a geothermal power station that uses a closed-loop system. Such a power station can recover all the gases after the extraction of energy and pump the gases back into the ground (Schnurr and Swatuk 46). Reinjection of water into the geothermal wells can help to reduce the number of underground gases that rise in the geothermal well. Apart from this benefit, reusing water helps to conserve groundwater resources. The town will need to carry out seismic surveys to find out whether the ground can sustain geothermal power drilling and power generation operations.
On the issue of cost, the town will save marginally on coal but may have significant cost savings if it uses natural gas to fuel the power plant. The main downside of using natural gas is that the plant will emit greenhouse gases. Since conservation is a main concern for the town, this option is not ideal.
The consultants would like to encourage the town to make a decision that best meets the aspirations of its people. The town must be aware that the decision its takes on this matter will affect the wellbeing of the current inhabitants and the next generation. While the options presented here are the most viable ones given the scale of the project, the town can also benefit from renewable sources such as solar and wind. The costs of these sources of energy are dropping every year, and they may make commercial sense for large scale application within the next decade.
Duffey, M R and J R Dorp. “Risk Analysis for Large Engineering Projects: Modeling Cost Uncertainty.” Journal of Engineering Valuation and Cost Analysis 23.1 (2000): 285-301. Print.
EPA. “Air Emmissions.” 2013. US Environmental Protection Agency. Web.
Greg, Holt, James Simonton and Mario Beruvides. “Engineering Economic Analysis of a Cotton By-Product Fuel Pellet Operation.” Journal of Cotton Science 11.3 (2003): 205-216. Print.
Harris, Frances. Global Environmental Issues. Chichester: John Wiley & Sons, 2004. Print.
Schnurr, Matthew A and Larry A Swatuk. Natural Resources and Social Conflict: Towards Critical Environmental Security. New York: Palgrave Macmillan, 2012. Print.