(304e) The Energy-Water Nexus of Thermoelectric Power Generation and Its Impacts in the Muskingum River Watershed in Ohio

Thermoelectric power plants generate electricity and flue gas scrubbers mitigate emissions from the plants. However, at the same time the power plants withdraw large quantities of water from the watershed, which corresponds to 45% of the total 2010 US water use [1], and emissions from the scrubbers cause deposition of nutrients in the watershed. Therefore, increasing electricity generation could increase water stress and deteriorate water quality. Also, in the watershed where power plants are located, other activities, such as farming, interact with the power plants since these activities also require water as well as energy from the power plants and release nutrients to the watershed. To prevent shifting of environmental impacts across multiple flows [2], the Energy-Water nexus between different activities in the watershed needs to be understood in assessing the impacts of power plants.

Muskingum River Watershed (MRW) in Ohio ranks fourth as the most polluted watershed in the US [3], and two coal-fired power plants and three natural gas-fired power plants are located in the MRW. In this work, a holistic analysis approach is employed to evaluate the water-energy nexus in the MRW. Various technological and ecological systems are considered. Technological systems include mining, thermoelectric power generation, and CO₂ conversion activities. Ecological systems include land use and farming practice. Alternative scenarios for each component are analyzed to address the nexus. An agro-ecological model, which is developed by the Soil and Water Assessment Tool (SWAT), is used to assess water quality and quantity [4], while engineering models are used for the power plants and scrubbing processes.

Fossil fuel power plants not only require a huge amount of water, but also emit 28% of the 2016 US greenhouse gas emissions [5], 67% of the 2014 US SO₂ emissions, and 12% of the 2014 US NO_x emissions [6]. Therefore, ecosystem services, such as water quality regulation, air quality regulation, and climate change regulation, play an important role in mitigating nutrient runoffs and air emissions. To account for the role of ecosystems, Techno-Ecological Synergy framework is applied in analyzing the impacts of activities in the MRW [7,8]. In this analysis, the trade-offs between water quality, water quantity, net electricity generation, carbon footprint, air quality, and net present value are identified. Various scenarios are considered to suggest better solutions that are ‘win-win’ in terms of multiple objectives.

Considering the Energy-Water nexus in the analysis will avoid shifting of the environmental impacts across multiple flows because interactions between flows are identified and all flows are included as objectives [2]. This work could be applied to any watershed and could be extended to address the Food-Energy-Water nexus by including food productions from farming activities as another objective. Addressing the nexus could help businesses and policy makers in making decisions to improve the sustainability of the watershed.

References

[1] Maupin, M.A. et al. Estimated use of water in the United States in 2010. U.S. Geological Survey, Reston, Virginia (2014).

[2] Bakshi, B. R., Gutowski, T. G. & Sekulic, D. P. Claiming Sustainability: Requirements and Challenges. ACS Sustain. Chem. Eng. 6, 3632–3639 (2018).

[3] Inglis, J. & Dutzik, T. Wasting our waterways: Toxic industrial pollution and restoring the promise of the clean water act. Environment America Research & Policy Center, Boston, MA (2006).

[4] Khanal, S., Lal, R., Kharel, G. & Fulton, J. Identification and classification of critical soil and water conservation areas in the Muskingum River basin in Ohio. J. Soil Water Conserv. 73, 213–226 (2018).

[5] Inventory of U.S. greenhouse gas emissions and sinks: 1990-2016. U.S. Environmental Protection Agency, Washington, D.C. (2018).

[6] 2014 National Emissions Inventory (NEI). US Environmental Protection Agency. https://www.epa.gov/air-emissions-inventories. Accessed on Apr 13 2018.

[7] Bakshi, B. R., Ziv, G. & Lepech, M. D. Techno-ecological synergy: A framework for sustainable engineering. Environ. Sci. Technol. 49, 1752–1760 (2015).

[8] Gopalakrishnan, V., Bakshi, B. R. & Ziv, G. Assessing the capacity of local ecosystems to meet industrial demand for ecosystem services. AIChE J. 62, 3319-3333 (2016).