The Solar power / Water Nexus | 11/07/14
by John Brian Shannon
Separate from discussions about airborne coal power plant emissions, are the high levels of water usage caused by obscenely high coal power plant water requirements. Water usage by power plants are directly proportional to the downstream water loss experienced by farmers, citizens, and other water users such as wildlife.
In some regions of the world, there exists acute competition for water resources as coal power station operators vie for water with agricultural, urban, and other users of water — while areas with plentiful water find their power plant choices aren’t constrained by water supply issues at all.
But the era of increasing water shortages and frequent drought seem here to stay in many regions, and the huge volumes of water required by some power plants is becoming a factor in the decision-making process as to which type of power plant is most suited for any given location.
Therefore, the conversation is now arcing towards the local availability of water and thence, to the most appropriate type of power station to propose for each location.
So let’s take a look at the water usage of five common types of power plants:
- Coal: 1100 gallons per MWh
- Nuclear: 800 gallons per MWh
- Natural gas: 300 gallons per MWh
- Solar: 0 gallons per MWh
- Wind: 0 gallons per MWh.
While 1100 gallons per MWh doesn’t sound like much, America’s 680 coal-fired power plants use plenty of water especially when tallied on an annual basis.
The largest American coal-fired power station is in the state of Texas and it produces 1.6 GW of electricity, yet it is located in one of the driest regions on the North American continent. Go figure.
At one time as much as 55% of America’s electricity was produced via coal-fired generation and almost every home had a coal chute where the deliveryman dropped bags of coal directly into the homeowner’s basement every week or two.
But in the world of 2014, the United States sources 39% of its electricity from coal power plants and this percentage continues to decline even as domestic electricity demand is rising.
Texas Utility Going Coal-Free, Stepping Up Solar
In a recent column by Rosana Francescato, she writes;
“El Paso Electric Company doubles its utility-scale solar portfolio with large projects in Texas and New Mexico. As if that weren’t enough, the utility also plans to be coal-free by 2016.” — Rosana Franceescato
She goes on to tell us that EPE serves 400,000 customers in Texas and New Mexico and gives credit to the foresighted management team. El Paso Electric is already on-track to meet the proposed EPA carbon standard. Their nearby 50 MW Macho Springs solar power plant about to come online is on record as having the cheapest (PPA) electricity rate in the United States.
This solar power plant will displace 40,000 metric tonnes of CO2 while it powers 18,000 homes and save 340,000 metric tonnes of water annually, compared with a coal power plant of the same capacity. That’s quite a water savings in a region that has been drought-stricken in 13 of the last 20 years, only receiving 1 inch of rainfall per year.
In February 2014, EPE signed an agreement for the purchase all of the electricity produced by a nearby 10 MW solar installation that will 3800 homes when construction is completed by the end of 2014. And they are selling their 7% interest in a nearby coal power plant. Now there’s a responsible utility company that makes it look easy!
Solar’s H2O advantage
The manufacture of solar panels uses very little water, although maintenance of solar panels in the field may require small amounts of water that is often recycled for reuse after filtering out the dust and grit, while other types of energy may require huge volumes of water every day of the year.
Wind’s H2O advantage
Wind turbines and their towers also use very little water in their construction and installation, although some amount of water is required for mixing with the concrete base that the tower is mounted on at installation.
In the U.S. which is facing increasing water shortages and evermore drought conditions as global warming truly begins to take hold in North America, switching to a renewable energy grid would have profound ramifications. Estimates of water savings of up to 1 trillion gallons could be possible if utilities switched to 100% renewable wind and solar power with battery backup on tap for night-time loads and during low wind conditions.
Midway through that transition, the present water crisis in the U.S. would effectively be over. Yep, just like that. Over.
China’s Looming Water Crisis
China’s looming water crisis has planners moving to taper their coal and nuclear power generation construction programmes. You can’t operate these plants without the required water, even for a day. Yet, the people who live and grow crops and raise livestock in the surrounding areas need access to undiminished water supplies. What good is a coal power plant if everyone moves away due to a lack of water?
There are very legitimate reasons nowadays to switch to solar and wind generation — and the reduction of airborne emissions used to be the prime consideration and may remain so for some time, however, massive reductions in water consumption might now prove to be the dealmaker in some regions — and the emission reductions may now be viewed as the happy side benefit! Wow, that’s a switch!
Of course, the benefits of solar and wind power will still include no ongoing fuel costs, very low maintenance and the lowest Merit Order ranking (the wholesale kWh price of electricity) of any energy.
Granted, there are locations where renewable energy doesn’t make sense, such as some Arctic or Antarctic regions. In these places solar simply isn’t worthwhile and wind levels may not be sufficient to make the economic case. Biomass may be a partial solution in these areas and there may be the opportunity for geothermal energy — although finding ‘hot rocks’ underground near population centres is much more unlikely than many people may realize.
But in the future, the vast majority of locations will be powered by renewable energy paired with a battery backup or a conventional grid connection — or both. And its a future that’s getting closer every day.