Water and carbon - a critical link

Date : 15 July 2010

More often than not, sustainability issues are closely related. Water and carbon are a good example.

This article explores just how the two are inexorably and critically linked.

Water and power generation + droughts = power shortage

Large cooling towers are a stark reminder of the role that water plays in energy generationWater plays a vital role in the energy generation sector. In the UK, nearly 30% of water abstraction is undertaken in connection with generating electricity, second only to public water provision in terms of importance.

Water is vital for generating steam to drive turbines and for cooling equipment in both conventional and nuclear power stations. Water extracted will condense and can be reused once the water has sufficiently cooled, hence the large cooling towers that are built next to power stations. Without this cooling water, the ability to generate energy is reduced. The European drought of 2003 resulted in French nuclear plants cutting their exports of electricity by over 50% (Source: UNEP). France normally exports 18% of the electricity it generates.

In the case of hydroelectricity, water is the direct provider of energy. Once captured, it drives turbines to generate power. In Spain, the 2005 drought led to a reduction of 36% in national hydroelectric power (Source: DG Environment European Commission).

Energy to clean and distribute water

Energy is needed to clean and pump water. About 1% of the total UK greenhouse gas (GHG) emissions are directly related to the water industry (Source: Water UK). Without change, as the cost of energy increases, so too will the cost of water. In response, the UK water industry is committed to reducing energy consumption and increasing the use of renewables to break the link between the water use and energy.

Flooding and energy

In many parts of the world, energy is required to pump water up and out of low lying areas. Without constant pumping, areas would quickly succumb to flooding. For example, 25% of the land area of Holland is below sea level. The need for pumps to respond to flooding risk either from the sea or land-side is obvious.

Desalination – providing clean drinking water

With some 97% of the world’s water being in the form of seawater, desalination looks like an attractive option to deal with fresh water shortages. In fact, there are already some 15,000 desalination plants operating globally (Source: Chartered Institute of Water and Environmental Management). In Beckton, East London, Thames Water’s desalination plant will provide up to 140 million litres of drinking water per day.

In Beckton, desalinating brackish water (a tidal mix of salt and fresh), is less energy intensive than desalinating seawater (20% more energy than conventional systems for brackish, 55% for seawater) and Beckton will use 85% of the water as opposed to only 50% when desalinating seawater (Source: Thames Water). The London plant is needed to supply an increased London population, combined with an increase in the demand for domestic water.

Water and energy

So, like many other sustainability issues we cannot consider water and energy in isolation. Today, we need to focus on energy effective methods of clean water production as well as developing new energy systems that are less water reliant. The link between energy and water needs to be broken to reduce reliance and risk.