Lower electricity costs for a water-starved world

Posted Tuesday, October 15, 2013 in Sustainable Maine

Lower electricity costs for a water-starved world

An Appalachian water wheel. (Brad Smith)

by Paul Kando

The nation’s water supply is under considerable strain and power plant cooling accounts for more than 40 percent of  U.S. freshwater use. Power plants lose additional billions of gallons of freshwater daily through evaporation. Drought and increasing power demand further strain water resources. Low river and pond water levels and high water temperatures can force power plants to curtail their output in order to avoid overheating and harming local water bodies. When power demand and fresh water needs collide in this way, customers are either left with little or no electricity or pay higher electric bills for power their electric utility had to purchase from elsewhere, usually at premium prices, while water shortages loom on the near-horizon. This occurred in several places during the past two summers.

Continuing business-as-usual is not an option. Future power generation will further endanger water supplies, unless we replace aging power plants with water-smart options like energy efficiency and renewable energy. “Making low-carbon, water-smart choices is a high-stakes effort. The choices the power sector makes near term will affect water resources, our climate and long-term hydrology, and the power sector’s long-term resilience,” says Peter Frumhoff, chair of the Energy and Water in a Warming World Initiative (EW3), a collaborative effort of scientists led by the Union of Concerned Scientists (UCS). “We set electricity and water on a collision course years ago. Now we must build a power system hard-wired not for risk, but for resilience.”

Low natural gas prices and the retirement of old, uncompetitive coal-fired power plants are prompting significant changes in the electric power industry. A UCS-led study -- “Water-Smart Power: Strengthening the U.S. Electricity System in a Warming World” -- found that choices the power industry makes now will determine how much the energy sector will tax the nation’s threatened water supplies and contribute to climate change in the decades to come. “Our electricity system clearly isn’t able to effectively meet our needs as we battle climate change and face a future of expanding electricity demand and increasing water strain,” says Erika Spanger-Siegfried, a senior analyst in the UCS Climate & Energy Program and co-author of the report. “As old plants are retired or retrofitted and new plants are built, we’ve got to untangle our competing demands for water and energy.”

The study found that even as electric utilities shifting to natural gas decrease water use in the coming decades, their remaining needs could still harm water-strained regions. The shift to natural gas would also do little to lower the power sector’s carbon emissions. Under the industry’s current business-as-usual path, emissions would stay within 5 percent of current levels and water use would not drop significantly until after 2030. In our water-constrained world, a 20-year delay in tackling the problem leaves the power industry unnecessarily vulnerable to drought and exacerbates competition with other water users.

We can bring water use down faster and further, but only by changing how we generate our electricity. Near-term options to reduce the power sector’s water and climate risks include upgrading power plant cooling systems with technologies that ease local water stress; giving priority to low-carbon, water-smart energy choices; and integrated energy and water resource planning. Maximizing energy efficiency and renewable energy use, like solar and wind, could reduce water use by as much as 97 percent from current levels by 2050, most of the drop occurring within the next 20 years. The approach would also cut carbon emissions by 90 percent from current levels.  Importantly, converting to renewable energy for power generation would also reduce –  not increase, as some would have us believe – the consumer  price of electricity, the report found.

Based on a sample of several hundred energy audits, 58 percent of Maine houses have adequate solar access. If a square foot of photovoltaic (PV) panel captures about 17.6 kWh of electricity per year, my house, with an average sized south facing roof of 16x30 feet, has a total generating capacity of 8576 kWh/yr. If, in round numbers, the average Maine solar roof can produce 8,000 kWh of power per year, and there are 400,000 houses in Maine, 58 percent (232,000 houses), together would produce 1,856,000,000 kWh, (1,856,000 MWh, 1,856 Gwh) of power. This is electricity that would not have to be produced by water- and fuel-hungry central generating plants. Furthermore, the lion's share of PV power would be generated during midday summer peak-demand hours, on warm, sunny days.

Maine's 2013 Natural Gas fired generation was 355 GWh, hydro 351 GWh, other renewables 295 GWh.  So if just 1/5 of homeowners with well aligned roofs installed PV panels to full capacity, it would become Maine’s leading method of electric power generation. Maine Yankee produced 4,748 GWh per year, so the estimated production from suitable house roofs would be equivalent to 40 percent of Maine Yankee's annual generating capacity.  And we haven’t even mentioned wind and tidal power, biomass, or combined heat and power generation using methane from sewage and organic solid waste.

In the words of Robert Jackson, a Duke University environmental scientist, "we have a tremendous opportunity before us. By increasing energy efficiency and renewables, we can cut greenhouse gas emissions and water use, improve the quality of our water and air, and save money and lives at the same time. How often do we get a chance like that?"

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