Via The Guardian, a look at the amount of energy we use to pump, clean and transport water:
In the water-food-energy nexus, the relationship between water and energy may appear obvious. Water is used to create energy through hydro-power for example, or to cool power stations or to mine fossil fuels. But there’s another side to this ‘water for energy’ equation, which arguably has a greater impact on the nexus: the energy needed to pump, clean and transport water or ‘energy for water’.
The US alone uses 520bn kilowatt‐hours (kWh) to move, treat and heat its water, which accounts for up to 60% of the energy bill in some cities, and 90% of the energy bill on some farms. This equates to 13% of the entire electricity use in the US, and more than 290m metric tons of carbon dioxide (equal to the annual emissions of 53m cars) each year.
“In many areas there is no other way than to pump water from the source to the end user, because the end user lives at a higher altitude than the source,” explains Gérard Payen, president of AquaFed, the International Federation of Private Water operators. “This is the case when you pump water from an underground aquifer.
He adds: “The world is now more than half urbanised, people live in cities, and for them to have water at home they need water to be pressurised in order to go up to the top floors.”
In order for that water to be drinkable, it also needs to be treated. Wastewater treatment amounts to approximately 3% of all electricity used in the US.
“Every year there is more energy used for water than the year before,” says Payen. “It is a big concern … the work that is included in [moving] a cubic metre of freshwater is increasing because of increased pollution, [and] because of urbanisation requiring fetching water from farther and farther away.”
Much of that is also done needlessly: in England and Wales in 2010-11, 2,559 megalitres of water (the equivalent of 1m litres) were lost per day through leaky pipes.
In regions of water scarcity, all this is evidently unsustainable. The US leads the way in energy-for-water research, primarily because it is home to several such regions. A report by the Atlantic Council found that California uses 20% of its electricity, 30% of its natural gas and 88bn gallons of diesel fuel a year for the sourcing, moving, treating and heating of its water. In south-central states, it predicted that annual per capita electricity consumption will increase from 400 to 700 kWh per year, and in west-central states, from almost 500 to more than 700 kWh, as “increasing water and energy demands butt up against declining aquifers.”
There are some innovations that are reducing this energy need. “The most interesting example is the way water is treated in water treatment plants and waste water treatment plants (WWTP),” says Payen. “These are industrial facilities where the quality of the water is changed through several processes … Today most of those plants try to use biological, natural processes. When you use biology, you don’t need as much energy. That is becoming standard now.”
A WWTP serving about 600,000 people in the San Francisco Bay area of California has achieved energy savings of around 70% per year.
Other innovations include desalination, the process of making freshwater out of sea or salt water. “Two decades ago, desalination was made from boiling water,” explains Payen. “You had to heat the water up to boiling point, then you would capture the vapour in order to have clean water. It required a lot of energy. Now another technology has been introduced – reverse osmosis filtration – where the energy consumption to make a cubic metre of water has been reduced continuously.”
At policy level, one controversial suggestion is to increase the market price of water. “The American public believes that access to cheap (or free) clean water is a right,” says the Atlantic Council. “Like electricity, the reality is that while water is no longer free, neither will it remain cheap; the price of water will rise for all users. Pricing policies may be one tool for reducing water use.”
When something has no value, it is often treated as such. “The pricing is important, but particularly of energy,” argues professor Declan Conway of the UEA Water Security Research Centre. “We know for example in irrigated agriculture, where farmers have access to cheap energy, either electricity or subsidised fuel for pumping, they tend not to use the water very efficiently – there are no real savings for them to do so. If the price of the energy is much higher, then they tend to use the water more efficiently.”
When asked if the water itself should cost more, he says that it may be a likely outcome, “but there are all sorts of other factors that need to be considered in terms of equity and … the social effects.”
The water scarcity that blights parts of the developing world requires an international response. Payen is a member of the UN Secretary General’s Advisory Board on Water and Sanitation. “On the UN board, the interactions between water and energy is something that is more and more discussed positively,” he says. “There is a big global event called the World Water Forum, a multi-stakeholder event with 10,000 people from NGOs, businesses, science institutes, governments … at a diplomatic level between governments the interaction between water, energy and food is more and more discussed.”
It sounds like a lot of talk and no action. But Payen firmly disagrees. “I know what action means … but in the global arena, talks are important to stimulate action.
He adds: “There are national policies on access to drinking water that have been stimulated by the UN talks, and those policies are driving action in the field in countries. So the fact that the water-food-energy nexus has started to be discussed at the UN level means that more national policies are influenced by those talks.” Let’s hope he’s right.
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