By Carey King
This weekend I joined a town hall forum in Cuero, TX, (DeWitt County, Texas) on the edge of the very hot Eagle Ford formation in South Texas. The Eagle Ford is currently a hot bed of activity for hydraulic fracturing for both natural gas and liquids production, depending upon where drilling occurs. As with many regions, local people there are concerned that hydraulic fracturing, and the associated activities surrounding that process (e.g. injection of ‘produced’ water and waste fluids, trucks on the road, extraction of drinking well water), might cause some deleterious impacts such as depleting or contaminating groundwater supplies. This town hall was one way of getting information out to landowners and the public.
By Liz Kalaugher
The Dead Sea region is long on history but short on water. To cast a more detailed eye on both, researchers have drilled a nearly 500m-long core from the middle of the Dead Sea to reveal more about its fluctuating water levels over the last 200,000 years.
Presented at the AGU Fall Meeting, the initial findings indicate that around 120,000 years ago, the lake almost dried up as a result of natural variation in climate. That doesn’t bode well for today’s scenario, in which extraction of water from the Jordan River for irrigation has almost entirely stopped the flow of water into the lake, and climate is projected to become warmer and drier. According to the UN, water shortage has the potential to cause conflict in the region.
A recent story in the domain of the water-energy nexus caught my eye. The story describes the Oyster Creek nuclear power plant in New Jersey will be shutting down in 2019, 10 years earlier than planned(http://www.app.com/article/20101208/NEWS/12080378/Oyster-Creek-to-close-10-years-early-in-2019), because it otherwise would have had to install cooling towers as a retrofit to the power plant. Environmental groups seem mostly behind the decision, but the Sierra Club is an example of one group that is far from satisfied(http://green.blogs.nytimes.com/2010/12/09/oyster-creek-nuclear-deal-draws-fire/). From the website of Exelon, enough electricity to power 600,000 average American homes.”
The reason for the decision to shut down the plant instead of retrofitting it with cooling towers stems from an US Environmental Protection Agency (EPA) rule. This rule calls for existing power plants that use “once-through” or open-loop cooling to cease using that design in replacement of wet cooling towers that withdraw less water. The reason this rule exists is that that once-through and open-loop cooling systems withdraw high flow rates of water (up to tens of thousands of liters per kWh) into the power plant to cool the steam cycle, and then discharge that water, now heated, back to the water source. Cooling tower systems withdraw much less 1-5 liters per kWh. In the case of Oyster Creek the water source is Barnegat Bay seawater, and the plant has been blamed for depletion of much of the marine life of the bay.
This EPA ruling that demands conversion of cooling systems from once-through to cooling towers is meant to mitigate impacts upon marine life from sucking in marine animals into the water intake, impinging larger animals onto filter screens, and discharging warm water that disrupts the ecosystem’s normal temperature balance. The drawbacks to this retrofitting are increased capital costs, slightly less net power output, and higher water consumption. Cooling towers are generally not used with intake of seawater because the cooling mechanism is via evaporation of the water. Thus, after the water evaporates, salt and other minerals deposit onto the cooling fins of the cooling tower creating a maintenance issue. The costs of chemicals and maintenance are generally not worth using cooling towers with seawater, although the use of cooling towers with freshwater is very common.
It is not clear if the 10-year early close down of Oyster Creek nuclear station is the beginning of a trend or one of a few to be highly affected by the cooling tower ruling. Given that Oyster Creek was the first large nuclear power plant in the US, it perhaps was destined to be one of the first to be retired. Any power plant using once-through cooling with seawater and that is planning on operating more than 5 more years will have a difficult decision to make. For power plants using seawater for cooling, I think it is likely that cooling tower retrofits will benefit the environment via less impacts on marine environments and lower profits (and/or higher electricity costs) of the power plant operator passing on to consumers to lower electricity consumption. Conversions of once-through to cooling tower on rivers and freshwater lakes will have lower economic impacts and the higher water consumption will affect water flows downstream. Thus, the environmental benefits are less clear, but lean toward more beneficial.
By Graham Cogley
In parallel with but, for practical purposes, independently of higher temperatures, we expect the environment to respond to an enhanced greenhouse effect with a more intense hydrological cycle. More evaporation where there is enough water (for example over the ocean) and a lot of evaporation already, and more precipitation where there is already a lot of precipitation. There are some pretty good indications that this is happening, but now a group of oceanographers has found more evidence in a surprising place (surprising to non-oceanographers like me, I suppose).
Kieran Helm and co-authors document just the kind of changes in the distribution of salt in the sea that you would expect if the hydrological cycle had intensified. Between 1970 and 2005 the maximum salinity of the water column, found at a depth of about 100 m, increased. In contrast, the minimum salinity, at about 700 m, decreased.
They analyzed the measurements by projecting them on to isopycnals, surfaces of constant density. The density of seawater increases when you add salt and decreases when you add heat. The payoff for the extra complexity is that heat and salt, added to or withdrawn from the ocean at the surface, are carried into or out of the interior of the ocean along these surfaces, and it is reasonable to interpret changes of salinity observed (strictly, inferred) on isopycnals as being due to changes at the surface.
The water balance of the atmosphere is a sort of zero-sum game. There isn’t room up there to store more than the equivalent of a few tens of millimetres of liquid water. In the big picture, more evaporation means more precipitation, but probably in a different place. Added water vapour stays in the air for long enough, on average, to be carried up to several thousand kilometres by the wind before it condenses and falls back out.
The atmospheric water balance is usually studied in terms of the single quantity P—E, precipitation minus evaporation, which (because I used to be a hydrologist) I will call Q for brevity. If Q is positive, the surface beneath the air column we are studying is getting wetter. If Q is negative, the surface is getting drier. If the air column is over the ocean, and its Q is positive, the ocean beneath, which is already as wet as it can be, is getting fresher (less salty), while if Q is negative the ocean is getting saltier.
The simplest way to make sense of the Helm results is to interpret the 1970-2005 changes in the distribution of salt as due to increases in oceanic Q of 7% in the higher latitudes of the Northern Hemisphere and 16% in the Southern Ocean, with decreases of 3% in the tropics. Each of these changes is subtle but statistically significant. (Another recent analysis, by Paul Durack and Susan Wijffels, suggests that the numbers might be on the large side.)
What has this got to do with glaciers? For one thing, Q is not the whole story. Glaciers that lose mass, as most do nowadays, are freshening the ocean, and sea ice that melts, as at the surface of the Arctic Ocean, is doing the same. But the thing that really interests me from the glaciological angle is the challenge. The hydrologists and now the oceanographers have produced evidence for a more intense hydrological cycle, and by implication a more intense greenhouse effect. Can we glaciologists rise to the same challenge?
A more intense hydrological cycle should make the shape of the snowline more curvaceous, lowering it by increasing snowfall near the equator and in the middle latitudes, and raising it by increasing evaporation in the desert belts. The snowline, remember, is at the altitude at which accumulation of snow is just balanced by losses due to melting and evaporation (actually, sublimation).
So the challenge is to detect snowline change due to the more intense hydrological cycle, against a background of snowline rise due to general warming. My guess is that, although it would be a big job, we might just be able to manage it. It would also be a race against time, because some of the most important glaciers for the purpose are losing mass so fast that they will not be with us much longer. But it would be worth the attempt, because demonstrating a change in the shape of the snowline is different from demonstrating simply that glaciers are losing mass, which in turn is different from demonstrating that the temperature is rising. The more independent but mutually consistent lines of evidence we have, the more confident can we be that we are on the right lines in interpreting what is happening to our world.
The latest Water Commission rulings have now come out on how to distribute water resources on the island of Maui, Hawaii. These rulings discuss how to distribute water from diversion ditches owned and operated by the last sugar-cane plantation of Hawaii Commercial and Sugar (HC&S) who is by far the largest water user on the island. The historical and future contexts of Maui are important in understanding why commercial and native Hawaiian interests have a very difficult time becoming aligned in any significant way.
In the late 1800s and early 1900s settlers to Hawaii established large plantations that over time grew sugar cane, pineapples and other crops. The best land for growing these crops generally lies on the leeward side of the islands that are relatively dry, sometimes almost desert-like. As a result of prevailing Northeasterly winds, the water is precipitated out of the Pacific clouds on the eastern sides of the islands before reaching the western portions of the islands. In order to provide the water required for large agricultural plantations, a series of diversions ditches over 100 miles long along takes water from the windward side of East Maui around to the central valley for the sugar-cane plantation.
However, over the last few decades, the plantations on all Hawaiian islands have been shutting down due to having difficulty competing economically on the global market. The HC&S plantation is the last of a dying breed in Hawaii, and many environmental and pro-native groups wouldn’t be surprised if the plantation shut down tomorrow – and for the most part they’d prefer that ending. As plantations on the islands have shut down the question arises as to how to allocate the water that previously diverted for agriculture. The case of reallocating some water from the previously fully diverted Waiahole Stream on Oahu has potentially set a precedent for using water for the purposes of native rights and environmental services. The native rights are primarily concerned with growing taro. Because taro is normally grown in flooded fields and patches that reside adjacent to streams and divert water into the fields before returning most of the water. Some species of taro can be grown without flooded fields, but those varieties are less common.
However influential the ruling for the partial reallocation of diverted water in the Waiahole case, it concerned water becoming available from the closing of a sugar plantation, Oahu Sugar. The water essentially became up for grabs. The cases on Maui for the Ne Wai Eha (West Maui) and East Maui concern a sugar plantation that is still operating. Furthermore, the push for renewable fuels in the US have led to federal grants going to investigate the use of Maui lands for biofuel development. This added pressure from the federal government may overcome any economic and legal pressures to either shut down HC&S the sugar plantation or divert more water to other uses on the island. Other pushes for general energy independence, an abundance of sun and water (when considering the entire island of Maui) generally make Maui as attractive as any location in the US states.
Whatever happens, the allocations of water and land use on Maui are a microcosm of the pressures of industrialized countries trying to make money and renewable energy using large plantations/farms and higher wages than countries like Brazil that also have the requisite natural resources, but currently not the same wage and environmental management pressures.
For a 30-minute interview with myself and two others on the energy-water nexus topic, with particular focus upon renewable energy, visit Renewable Energy World.
I just attended the conference Understanding, Measuring, and Managing Water Scarcity Risks and Footprints in the Supply Chain this past week. This conference was primarily attended by sustainability managers of corporations along with a few academics and non-governmental organizations. There was much discussion of how to measure water impacts of industry as well as how to act on measured or calculated information. Many of the speakers and attendees were familiar with several methods for measuring water “usage” such as the Water Footprint (www.waterfootprint.org) and the Global Water Tool of the World Business Council on Sustainable Development (www.wbcsd.org/web/watertool.htm). The former presents information on the green water (soil moisture for the most part provided by precipitation) and blue water (stored water in rivers, lakes, and aquifers) consumed in the supply chain of a product. The latter is a mapping program that allows businesses to understand if they have operations in regions of the globe that have water scarcity.
There was general agreement within the community that the Water Footprint is not properly used as Jason Morrison of the Pacific Institute summarized by saying “different interests use the term ‘water’ footprint’ to mean different things” for their own purposes. Technically speaking, the water footprint is in units of water volume per time. By multiplying by the time per product manufactured, one can obtain the water footprint in units of water per product. This last term is the one most commonly presented in such examples as the quantity of water needed for a pair of jeans or a cup of coffee. This water volume per product is a handy unit of measure that consumers and business people can easily grasp. The problem is that it doesn’t seem to be helping either water resource management practitioners or sustainability managers at companies.
The issue stems from culminating into one term the water consumed over a supply chain that occurs in time and in space. If your supply chain for a product occurs in more than one location and/or at more than one time, then by definition you cannot capture all of that information into a single number. Mathematically this is like taking the derivative of a number. Each time you take the derivative, you lose one degree of freedom or information. For example, the volume of a sphere is described as V = 4/3pir^3 and is in units of cubic meters (m^3) to describes a three-dimensional space. Taking the derivative of volume with respect to its radius results in the surface area of the sphere at A = 4pir^2 in units of square meters (m^2) to describe a two-dimensional space. Hence we went from three dimensions to two dimensions. If I show only the final value for the surface area of the sphere, say 1 m^3, I do not know that a sphere is being described. However, if tell you the equation for the sphere’s surface area and tell you it is equal to 1 m^2, then you know how to calculate the volume (or radius) because I have just provided more information that told you about the third dimension.
What does this have to do with water footprinting? Well, similarly to needing to know more than one piece of information about the surface area being described (need two of either equation, radius, and surface area) to know it is for a sphere, you need more than a single value for the water footprint of a product to understand the environmental impact caused by its production. For example, if a shirt requires water during farming of cotton and dyeing of the fibers, then one could present the information in two numbers on a bar chart (among many other means for presenting information). Part of the bar chart would represent the cotton farming, and the other part would represent the dyeing step. By telling people where you source your cotton and where you perform your dyeing, you have now presented more information – information again that cannot be understood using a single value. I have just described four pieces of information: water for cotton, water for dyeing, location for cotton, and location for dyeing. A map with the water consumption value in each location the water is consumed could present all four pieces of this information. I could go on for temporal components. The World Water Tool exists to take the information described in this paragraph to relate to water scarcity around the globe. They of course use a map for this.
This thought exercise is meant to show that people understand that describing environmental impacts is somewhat complex. In describing water flows for human appropriated needs, from a basic standpoint we should focus on avoiding the word “use” to describe water flows. Instead, use “consumption” to describe water that enters the system as a liquid and exits as water vapor or in another chemical form. Use “withdrawal” to describe water entering and exiting the system in a liquid form, and note that consumption is a subset of withdrawal. The water footprint is a consumptive descriptor that for the most part includes evapotranspiration (green water) on top of what the term consumption (the blue water component) takes into account. If we stick to some of these basic rules, we can better understand how human and ecosystem services are subjected risks in water availability.
According to Japanese researcher Taikan Oki and Shinjiro Kanae, approximately 500,000 cubic km of water per yr are evaporated over the ocean (437,000 cubic km) and land (66,000 cubic km).1 With water at a density of 1000 kg per cubic meter, this is 5×10^17 kg of water evaporated per year. Using a latent heat of vaporization for water of 2,270 kJ/kg, this means that a minimum approximately 1,135,000 exajoules per year (1 exajoule, or EJ, = 10^18 J) of solar energy are used to evaporate the world’s water and drive the much of the hydrologic cycle of the planet.
Given that humans consume approximately 500 EJ/yr in primary energy, this means that the Earth’s water consumes at least 2,000 times more solar energy each year when evaporating water that we consume in primary energy resources. Eighty-seven percent of this water is desalinated by evaporating from the oceans. So when we talk about desalinating water, or recycling water, just remember that it means that we are inherently deciding that 2,000 times our direct consumption of primary energy resources for the creation of fresh water is not enough!
So when we think if using desalination, but matching it up with carbon-free sources or technologies that are more efficient than a couple of decades ago, what we are really saying is that our original use of solar energy for water desalination is no longer sufficient for our purposes. With that mindset, should we rearrange our priorities in terms of the uses of water and locating people to where the solar resource combines with precipitation patterns and the Earth’s contours to deliver water to us renewably? Or should we continue to bet that energy will be cheap such that we become more dependent upon it for delivering fresh water? These kinds of questions are mainly for rich countries, as we can only be so lucky to have these options.
1Oki, Taikan and Kanae, Shinjiro (2006). Global Hydrological Cycles and World Water Resources. Science, 25 August 2006, Vol. 313. no. 5790, pp1068–1072, DOI: 10.1126/science.1128845.
On a recent trip to Brazil to understand water-resources management with respect to biofuel crop and other agriculture, I learnt much more about Brazilian energy policy. While in some cases, water-resource management is in its infant stages, in many others reductions of water usage have made great strides.
The total water flow in a sugar-cane-ethanol distillery is approximately 22 m3 per tonne of sugar cane processed, but new plants can be designed to withdraw only 1 m3 per tonne of cane. Most distilleries withdraw less than 5 m3 per tonne. Additionally, Dedini (the Brazilian vertically integrated company that sells industrial components and turn-key sugar-cane processing plants) has a plant design that can take green sugar cane, harvested by machine and without burning, and actually produce clean, fresh water instead of requiring it as an input.
Speaking of machine harvesting, the state of Sao Paulo, where more than 50% of cane is grown, has mandated that all sugar cane is harvested mechanically (i.e. by tractor) by 2014. The reason is to improve air quality during harvest season when the cane would otherwise be burnt before manual harvest. The cane is burnt to remove the leaves and “trash” from the stalk of the sugar-cane stalk and this leaves the main stalk with the sucrose and fiber. So much cane was being produced and harvested in a relatively small region that air quality was becoming unsafe for residents.
This practices of using mechanical harvesters for harvest was actually used as one of the criteria guiding the designation of Agriecological Zones for future sugar-cane agriculture. To prevent any perception of “food v fuel” argumetns for sugar cane in Brazil, the goverment has now set up the zones where sugar cane should be expanded. A sugar-cane developer cannot recieve goverment support via low-cost loans unless exapnding into these agricultural zones, and agriculture is generally too expensive without this government support. So, because mechanical harvesting is assumed not possible on lands with slopes greater than 12°, that slope limit was used as the criterion number. The other two criteria for determining the agricultural zones were climate (rainfall, temperature profile, etc.) and soil quality. The vast majority of sugar cane in the south and central parts of Brazil requires no irrigation except for possibly some during initial planting, and those areas in the new zones are anticipated to require little irrigation (˜200–300 mm/yr) if any at all, and it is not clear if the economic payoff will induce the investment in irrigation infrastructure.
Another, more social, aspect of Brazilian energy policy is the promotion of small farmers throughout Brazil for growing various crops for vegetable oils for biodiesel. The “pro-alcohol” programme was seen to leave out the small farmer as it is a large-scale industrial crop. Because sugar cane to ethanol is estimated to have a much higher energy return on energy invested than many oils to biodiesel, it is not apparent if people expect to make monetary returns similar to the industrial scale ethanol industry. Nontheless, there is an attempt to include more rural communities and farmers into Brazilian energy policy – for better or for worse.
Thus, from air quality to soil quality, Brazilian energy policy is promoting its cash crop of sugar cane. As the current land area used for Brazilian sugar cane is approximately 8–9 million ha, and the land used for cattle pasture is 180–200 million ha, we don’t have to worry about Brazilian biofuel development as a specific driver for removal of the Amazon rainforest. The Amazon is clearly restricted via the agriecological zoning for sugar cane. On the other hand, increasing pressure for beef may have a part to play as policing such as vast area is difficult to impossible. But there is a push for increasing the density of cattle on land in Brazil to prevent expanded land clearing for pasture.
In summary, there is sufficient land zoned for sugar cane for Brazil to produce approximately 4–5 times as much ethanol than is produced today (˜6.2 billion gallons in 2008). There is also generally a better climate (rain and temperature) and soils for first-generation and possibly second-generation biofuels feedstocks than in North America or Europe. Thus, it is important that the developed world understand its own agricultural practices for energy-related biomass and determine whether domestic water and soil resources are better preserved by importing and investing in Brazil or investing at home. But then perhaps this brings up a new set of domestic social sustainability questions …
This past week I had the pleasure of meeting with seven colleagues for a Water and Energy workshop in Brussels. The purpose of the gathering, organized by COST (Cooperation of Science and Technology) was to organize a set of case studies on the links between water and energy for a special journal issue and presentation at a side event during the United Nations Framework Convention on Climate Change conference in Copenhagen, Denmark this December (aka the Conference of Parties 15: COP 15).
The case studies span four continents and cover the breadth of interactions. I list here the topics and the colleagues (in attendance) working on the papers:
1. Food-Water-Energy in Spain (Anna Osann, Universidad de Castilla La Mancha)
2. How the carbon reduction policies in Australia will affect the Water-Energy Nexus (Debborah Marsh, Australian National University)
3. Water needed for bioenergy crops in Tuscany Region of Central Italy (Anna Della Marta, )
4. Energy-Water Nexus of Texas (Carey King, University of Texas at Austin)
5. Underground Thermal Energy Storage in The Netherlands (Adriana Hulsmann, Watercycle Research Institute)
6. Energy-Water Nexus – China Case Study (Xingshu Zhao, Chinese Academy of Science)
7. Opportunities for Greenhouse Gas reductions in water and wastewater supply, use, and treatment in England and Wales (Andy Howe, Environment Agency)
8. Conflicts and Synergies Between Climate Change policies and Sustainable Water Management (Jamie Pittock, Australian National University and WWF)
What has become more and more apparent as we study the ties between energy and water is that historically water has not proven as a constraint to energy development of supply and use. However, most of the world’s fresh water resources are now already allocated to one purpose or another. So as people want water for new energy (e.g. mining, cooling for electricity generation, growth of bioenergy crops, etc.) it is now beginning to be supplied at the expense of other water needs. Many times integrated water resource management planning has already set limits on the use of water in a certain river basin or region.
When water is fully allocated or already scarce, and new energy needs arise, a showdown can ensue. The question becomes: Is the sustainable and ecological mentality of water resource management going to influence the energy sector, or is the energy sector’s more exploitive and revenue-maximizing style going to overtake the water management priorities?
So far, it may still be unclear what position will win out as a couple of examples show. In Australia, an ongoing drought since the beginning of this century has caused power generating stations to ask for environmental flow restrictions to be lifted for certain rivers. The problem for them is that they needed the water for cooling, but are only allowed to extract the water when flows are sufficiently high. Because the flows were not high enough due to prolonged drought, and they successful in lobbying for the removal of certain river flow restrictions, they were forced to buy water from the rural water market in Australia. This was a major cause for electricity prices rising up to 270% last year for a certain period.
In Texas, a 200 mile interbasin water transfer project (“LCRA-SAWS”) from the central coastal region of Texas to the San Antonio Water System was studied for over seven years before recently being cancelled by the water supplier, the Lower Colorado River Authority. General cost overruns were much of the issue, combined with energy costs for pumping and restrictions for freshwater inflow into the Texas bays. However, these kinds of issues are not much of a stumbling block for China trying to keep its northern, now rather dry, agricultural regions productive and growing cities healthy. The “South North Water Transfer Project” is expected to take 40 years to construct 3 main arteries, transfer 38-43 billion m3 of water per year and cost almost 500 billion yuan (~ 75 billion US dollars). Additionally, there are plans for 83 GW (almost 1/10 of the US electric capacity) of hydropower dams to be constructed from 2005 to 2020. Natural river flows are not really an issue in China. They need electricity (hydropower) and water to maintain economic growth and thus, political stability.
When we look to the biofuels push, this is where we may see water management lose out. Agriculture already withdraws and consumes the most water of any sector. Historically, this has been for food production, and using water to grow food crops has been a fundamental use of water since the dawn of civilization. Using water to grow crops that then get converted to liquid fuels, on the massive scale of billions of gallons per year, is a more recent trend. Should irrigation water be used for growing biofuel crops? Is there some target percentage of irrigation water that should be an upper limit, given that some parts of the world are still malnourished? I think this is where the debate should go. I don’t believe that agricultural energy interests should be completely shut out from irrigation, but at the same time I don’t believe we should allow full reign of aquifers and surface water for irrigating biofuels. A common argument for some 2nd generation biofuel crops such as grasses and other cellulosic material, is that they can be grown on marginal lands. Well, marginal lands are just that, so the yields will be higher with fertilizers and irrigation. If irrigated water is subsidized for these purposes, then there is no reason to believe that the drive for higher yields and more fuels will not lead to irrigating crops grown in areas where we are led to believe it will not be used.