Comparative Assessment for Water Demand for Coal and Natural Gas-Based Power Generation

Transcription

1 Comparative Assessment for Water Demand for Coal and Natural Gas-Based Power Generation by Babkir Ali and Amit Kumar Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada

2 Background Objectives Methodology Water-demand coefficients Comparison Performance curves Key observations

3 Currently 41% of the electricity generated in the world is based on coal and expected to increase to 44% by 2030 [World coal Association, 2012]. Gas production in the world will increase with average annual growth rate of 2% from 2008 to 2020 and moderates to 1.6% up to 2035 to reach 5.1 trillion cubic meters (tcm) [IEA, 2011]. In the US, total water consumption by coalbased power plants is expected to be 21% higher in 2030 compared to 2005 and some plants may be vulnerable to water supplydemand conflicts [NETL, 2010].

4 Development of a framework to estimate the life cycle water demand for coal and natural gas power generation. Comparative assessment of life cycle water demand of 36 pathways for coal and 39 for natural gas. Assessment of impacts on water demand due to variation in the conversion efficiency of the power plants.

5 Development of unit operations for power generation from the two sources. Development of water demand coefficients over life cycle of upstream and power generation pathways. Development of curve profiles for water demand coefficients under different conversion efficiencies.

6 Coal mining Coal preparation Coal transportation Surface mining without revegetation Surface mining with revegetation Underground mining Other operations Ash handling Drinking Dust suppression Desulphurization Plant decommissioning Crushing Beneficiation Cooling system Once-through cooling Cooling tower Cooling pond Dry cooling Truck Rail Conveyor Slurry pipeline Coal-log pipeline Power plant technology Subcritical Supercritical Ultrasupercritical IGCC 6

7 Gas source Upstream processes Gas delivery Conventional gas Exploration Pipeline transportation Coal bed methane (CBM) Shale gas Other Well drilling Fracturing Water produced Well abandonment Storage Distribution Cooling system Power plant technology Once-through cooling Single cycle Cooling tower Combined cycle (NGCC) Cooling pond Cogeneration Dry cooling Steam cycle 7

8 SM=Surface mining, With V=With revegetation, UM=Underground mining, SUB= Subcritical, SUPR=Supercritical, USUPR=Ultra-supercritical, IGCC=Integrated gasification combined cycle OTC=Once-through cooling, CT=Cooling towers, CP=Cooling pond, DC= Dry cooling. All coefficients are for conventional transportation 8

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13 The least water consumption coefficient for coal pathways is obtained through surface mining without revegetation using conventional transportation with IGCC technology and dry cooling system (0.96 L/kWh). The least water consumption coefficient for NG pathways is obtained through conventional gas, cogeneration, and dry cooling system (0.13 L/kWh).

14 Water demand during the coal mining is with significant amount and should be taken into account when estimating the water required for complete life cycle of coal-based power plants. Higher conversion efficiency of NG power plants compared to coal based affected positively the water demand coefficients.

15 Financial Support through NSERC/ Cenovus/ Alberta Innovates Associate Industrial Research Chair in Energy and Environmental Systems Engineering and Cenvous Energy Endowed Chair in Environmental Engineering.

16 World Coal Association Coal & electricity. Available at: [accessed 13/10/2014]. International Energy Agency (IEA), Special Report: Are we entering a golden age of gas. World Energy Outlook NETL Deborah Elcock, James A. Kuiper. Water Vulnerabilities for Existing Coal-Fired Power Plants. DOE/NETL-2010/1429. Available at: [accessed 10/10/2014].

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