The intimacy of the relationship between water and power generation is reflected in a couple of articles in this month’s issue (see pp 17-19 and pp 21-23). Recent estimates for the USA suggest that it takes around 25 gallons to produce one kWh of electricity – prompting the comment, from the US Department of Energy’s National Energy Technology Laboratory, that the average American “may indirectly use as much water turning on lights and running appliances” as is consumed “in taking showers and watering lawns.”
The existing US fleet of fossil fuelled power plants is believed to account for around 40% of the water used in the USA, second only to agriculture. Similar high figures are estimated for power generation water abstraction in other countries, for example, in the UK the percentage is essentially the same as that in the USA while in Germany some estimates have put the figure as high as 60%.
Against this background the power industry must take seriously growing worldwide worries about the future availability of water and the potential implications for power plant development. Globally, water is becoming an increasingly contentious issue in power plant permitting, while, in certain regions of the USA recent years have seen a sharp rise in the price of water rights.
These concerns have spawned a number of research projects, notably in the USA, aimed at lowering power plant water consumption, eg through use of non-traditional water sources such as underground mine pools and “produced waters” from coal bed methane. Another possibility that is now looking increasingly promising – following a series of successful small scale tests conducted towards the end of last year at the University of North Dakota’s Energy and Environmental Research Center (EERC) – is extraction of water from flue gases. This could be applied to both coal fired and gas fired plants.
Power plant flue gases represent a major potential source of water (arising from the combustion process itself, water in the fuel and water used in flue gas treatment processes). A 470 MW combined cycle plant is estimated to throw roughly 750 equivalent liquid gallons of water vapour into the atmosphere every minute. And according to the research at EERC, which was carried out by Siemens Westinghouse, with support from the US Department of Energy, dehumidification using calcium chloride as the desiccant looks like a good way to go.
Having identified Niagara Blower as a potential vendor of the dehumidification technology itself, Siemens Westinghouse is now looking for a partner in the power generation business to provide the host power plant for a demonstration project.
This initial site is likely to be in one of the more arid regions of the USA, eg the south west. But interest in reducing water consumption is by no means confined to those regions. In Europe the need to adopt best available technologies under the EU’s IPPC (Integrated Pollution Prevention and Control) requirements, for example, is likely to act as a driver promoting technologies that minimise water useage, such as air cooled condensers, and, in the longer term, flue gas water extraction – should the technology prove to be feasible and become available. The Chinese have also identified reduced water consumption as a key requirement for future power plant technologies. So if the demo project shows that flue gas water extraction can deliver in practice what it promises in theory, it should be assured of a large and global market.
Letter to the editor
Dispelling hydrogen myths
There’s no need to cite ‘gossip’ about the Hypercar® and vehicle-to-grid approaches that I invented in the early 1990s (Wollensky, July 2004, p39). Both are described in numerous publications, free at www.rmi.org since 1993. These two concepts are compatible but distinct. Hypercars are ultralight, ultra-low-drag, hybrid-electric vehicles whose threefold-lower tractive load can greatly accelerate the adoption of fuel cells: the 3x smaller stack becomes affordable many years earlier, and the 3x smaller tanks package well, providing normal driving range with presently commercial 350 bar tanks (www.rmi.org/images/other/Trans/T04-01_HypercarH2AutoTrans.pdf). Such fuel cell vehicles can readily, but need not, be configured as optional ‘power plants on wheels’ when parked, which US cars are about 96% of the time.
My being ‘against large central power plants’ may be famous but is mischaracterised. Rather, my team’s Economist 2002 Book of the Year, Small Is profitable: the hidden economic benefits of making electrical resources the right size (www.smallisprofitable.org), explains that matching generating scale to load scale, which is usually but not always small, yields more than 200 ‘distributed benefits’ that typically increase economic value by an order of magnitude. This doesn’t mean all sources should be small, nor that scale should be determined by some doctrinaire preference; rather, that to save money, sources should be the right size for the job. Gigawatt- and hundreds-of-megawatt-scale loads are rare, and are already well served by solutions that are uncompetitive and unreliable for serving distributed loads.
‘Twenty Hydrogen Myths’ (free at www.rmi.org/images/other/Energy/E03-05_20HydrogenMyths.pdf) explains why nuclear electricity is a hopelessly uneconomic marginal source of hydrogen. In this I fear my esteemed friend Geoffrey Ballard has erred. Large-scale wind power has a plausible long-term market path to becoming a hydrogen source competitive with reformed natural gas, but central thermal electricity, whether from nuclear or fossil fuel, does not.
The dismal inherent economics of nuclear power are summarised at pp 258-260 of Winning the oil endgame (free at www.oilendgame.com). This new Pentagon-cosponsored study shows in detail how to get the US completely off oil over the next few decades, and revitalise its economy, led by business for profit.
Devoting further resources to the illusion that nuclear power – probably the costliest known energy source on the margin – can help with the oil or climate problems, as the World Nuclear Association doubtless proposes, will actually make both problems worse by diverting investment from resources that cost less and can therefore buy more solution, faster, per dollar spent. Nuclear advocates who don’t understand that their option costs 2-30x more per delivered kWh than three abundant and widely available alternatives (end-use efficiency, gas-fired industrial or building CHP, and wind power) will continue to dissipate their shareholders’ money and the public’s trust.
Amory Lovins, CEO, Rocky Mountain Institute, Inc