Water and energy

A hydropower station

There are close links between the water and the energy sector.

Water for energy

Water is an indispensable input for energy supply. Water can generate energy by powering the turbines of hydropower plants. It is needed as a cooling agent for coal-fired, gas-fired and nuclear power plants, and for irrigating crops grown for biodiesel or biogas. Water is also an essential element in the production of solar cells or in the operation of solar thermal power plants. It is also needed for mining fossil fuels.

Hydro power is becoming increasingly important as a renewable source of energy. Especially in planning major dam projects, however, social and environmental aspects need to be taken into account alongside economic interests. Dams can lead to conflicts over the use of water. Where water is held back by a dam for the purpose of generating energy, this may negatively affect the availability of water for irrigation downstream.

Systematically taking into account the nexus perspective helps counter competing water demands. In the region of the Middle East and North Africa, German development cooperation projects involve, for instance, developing plans and strategies that support the shared use of resources. For the construction of the first major solar thermal power plant in Morocco an analysis of water needs was carried out at an early stage of the project and a dialogue with representatives from the water sector and from irrigated agriculture was facilitated.

Energy for water

We not only use water to generate energy, we also use up energy when we use or consume water – we need energy for water purification, for desalination and for transporting water, for wastewater treatment and, in particular, for heating water for household and industrial use.

Wastewater: Treatment plants use a lot of energy. Modern systems tap the potential energy in wastewater using decomposition processes to turn sewage sludge into biosolids and biogas. Instead of being burnt off, the biogas can be recovered and used to generate power.

Drinking water: The desalination of seawater and brackish water is a very promising method as a way to ensure future drinking water supply. Right now, however, this technology still uses a lot of energy, which means that it has a large carbon footprint. Combining this technology with solar and wind energy could be the key to solving this problem.

Interactions and interdependencies: Energy costs have a huge impact on water consumption. Especially in agriculture, the cost of irrigation depends almost entirely on the cost of the energy necessary for operating the pumps. If energy is subsidised, farmers are able to irrigate their fields all the year round, which leads to higher yields. In many countries, such subsidies therefore serve as an instrument to fight hunger and poverty, and promote the economy.

Yet, if energy is cheap or free, there is no motivation to use resources efficiently and sustainably and – in the best case – save water. In order to place the agricultural sector on a forward-looking trajectory in the way it uses energy, German development cooperation projects are promoting solar-powered irrigation techniques, for example. In such cases, water use needs to be strictly regulated so as to prevent water resources from being over exploited. Any excess solar energy that is generated can be fed into the grid.

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