The current way we use water is unsustainable. Approximately 3.2 billion people worldwide, nearly half of the global population, live in areas experiencing water scarcity and around a third of our largest groundwater systems are under stress. The demands of global economic growth mean that pressure on water resources is predicted to increase in the coming years.
Industry is a big user of water, accounting for between 15-20% of annual freshwater withdrawals. This includes water consumed to provide energy such as gas and electricity to homes and businesses. Energy consumption is currently six times what it was in 1950 and is by up to 55% by 2030 due to population growth and industrial development. This will hugely increase the demands on freshwater supplies worldwide unless we rethink how we manage and use water.
How Is Water Used In Practice In Power Generation Plants?
The relationship between water and power supplies is often referred to as the water-energy nexus. Providing energy uses water and providing water uses energy. Both need to be used sustainably to prevent depletion of resources.
The water footprint of the energy sector is currently around 378 billion cubic meters per year. Electricity is the most water-intensive power to produce, contributing to around 90% of the global energy water footprint. Analysis of future water use has found that the amount of water required for energy production could increase by between 37-66% over the next two decades.
Water has many roles throughout the production of energy supplies, from start to finish. These include:
- Mining and Extracting Processes – Water is crucial for the drilling and mining of natural gas, coal, oil and uranium.
- Refining and Processing – Fuels such as natural gas and oil need refining before they can be used as fuels, which requires a lot of water.
- Power Generation – Thermoelectric plants use boiled water to produce steam to generate electricity. Water is also vital to hydroelectric plants which capture energy in moving water.
- Fuel Transportation – Water is used to transport fuels such as ground up coal through pipelines and is also used to test energy pipelines for leaks.
- Growing Crops For Biofuels – This alternative to fossil fuels is great for reducing carbon emissions but is more of a drain on water supplies if water-intensive irrigation methods are used.
- Waste Disposal and Pollution Control Technologies – Water is needed for these processes to ensure standards are met.
The production of energy also has implications for water quality. For example, extraction processes can contaminate groundwater which can affect drinking water quality.
Different Types Of Energy Plants and Their Water Footprint
There are a number of different types of power plants, all with their own water footprint. These include:
- Coal-fired Plants – Between 79-2100 cubic meters per unit of power output
- Gas-fired Plants – Between 76-1830 cubic meters
- Nuclear Plants – Between 18 – 1450 cubic meters
- Hydroelectric Plants – Between 300 – 850,000 cubic meters
- Geothermal Plants – Between 7 – 759 cubic meters
- Solar Plants – Between 118 -2180 cubic meters
- Wind-powered Plants – Between 0.2 – 12 cubic meters
How Can We Improve Things?
As can be seen in the numbers above, it’s not simply a case of moving to more green forms of power as some are more water-intensive. Geothermal and wind power have a smaller water footprint than fossil fuels, but the footprint of solar energy is not much different and hydropower uses more water (mainly through evaporation from manmade reservoirs).
It’s clear we need to move away from coal and gas but the shift to renewables needs to be done in a ‘water smart’ way. This means incorporating alternative supplies of water into the mix to reduce freshwater withdrawals. In practice, this could be making use of wastewater recycling systems, rainwater harvesting systems (especially in areas with high precipitation), or solar-powered or wind-powered water desalination systems.
Energy suppliers can also look at improving their water management strategies, moving towards less water-intensive methods of extracting, processing and distributing fuels and making use of water-efficient new technologies.
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