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Energy the nexus of everything: February 2010 Archives

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 ( and the Global Water Tool of the World Business Council on Sustainable Development ( 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 = 4/3*pi*r^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 = 4*pi*r^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 5x10^17 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.

The economic struggles since mid-2008 are bringing out factions that highlight both the uncertainty of the future together with ignorance of how the past has led us to where we are today. In the US, we have the conservative "Tea Party" movement of the right that is complaining about excessive government spending and the liberal "anti-banking" faction on the left that is fed up with the fat cats on Wall Street skimming too much off the top. Both sides are correct in coming to grips with the fact that large organizations and bureaucracies (e.g. government and banks) are having a harder time coping with the current economic and social problems of today.

What has unfortunately been quite absent from most of the political discussions about how to get the economy "back on track" is the true role of energy resources and technologies. With all of the talk in the United States about the need to "connect the dots" for the "War on Terrorism", what we really need to do is accept the way the energy and economic dots are connected in our modern industrial society.

By taking the following factors into account and enhancing our knowledge of how we can and cannot affect these indicators, we will "connect the dots" on our future as well as possible:

  • (1) Jevon's Paradox states that increased efficiency in the use of resources (in this case energy resources) through the use of technology and structural change increases total resource consumption.
  • (a) Policy point: if we target increasing efficiency, we can expect to only delay environmental problems.
  • (2) The energy return on energy invested (EROI) for the combination of energy resources, renewable and fossil, together with technology that converts those resources into services dictates the level of complexity attainable by society.
  • (a) Policy point: society seems to have reached a level of complexity in the last 1–3 decades such that:
  • (3) The EROI of energy services has been extremely high with the use of fossil fuels, and EROI will eventually come to a value such that it is equal for fossil and renewable resources. That time of EROI equality will mark a turning point in human civilization.
  • (4) The human species has now grown in size that it is capable of affecting the environment on a global scale as opposed to only very localized impacts before the industrial revolution.

The connecting of the dots goes as follows:

  • (1) Humans organized into agrarian societies, and this was beneficial because it raised the EROI from farming, where the energy produced in this case was that energy embodied in food, not primary energy for operating machinery. The invention of tools and use of beasts of burden (horses, oxen, etc.) also enhanced human EROI (i.e. the amount of human energy required to grow food for human consumption).
  • (2) The discovery of fossil fuels and subsequent technological change to enable further exploitation of fossil fuels led to the industrial revolution and the capabilities of production and economy in our present industrialized society.
  • (3) Resource constraints via any combination of technical, physical, economic, and political factors act as a driver to increase efficiency in the use of energy resources, but there are thermodynamic limits.
  • (a) For example, the Arab oil embargoes of the 1970s drove up the price of oil which in turn drove the US and Europe to increase fuel efficiency of vehicles to get the same service (move passenger and cargo from point A to point B) with less fuel, or energy. Subsequently, energy efficiency increased since the 1970s but the rate of consumption of energy changed from exponential growth to linear growth, and economic growth also slowed compared to the previous post World War II rates for the US.
  • (4) Today the rate of technological change in terms of increased energy efficiency and high EROI has not increased at the same rate as needed to enable economic growth equal to the pre-2000 years and subsequently the top of the economic food chain has decided to hoard recent profits at the expense of distributing those profits to the middle and lower classes. This is evidenced by the increased income gap between the top and the bottom.
  • (5) The inherently lower EROI of renewable resources will not enable the same level of economic production and societal complexity as provided by higher EROI fossil fuels. This is because renewable technologies are based upon current flows of energy (e.g. sunlight, wind, waves), as compared to fossil fuels which are based upon stocks of energy stored over hundreds of millions of years.

To contemplate the final point above, consider that Earth stored the renewable energy of the Sun (in the form of biomass) on the order of 100 million years, and now we are consuming this energy on the order of hundreds of years. What humans learn and choose to practice during this century will dictate the type of societies that are even possible after peak fossil-fuel production.