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Coal & water

The energy sector, like all industrial processes, is water intensive. Water as a resource is growing more scarce, so it is important that we use water resources efficiently and conserve supplies.

According to the UN, by 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity, and two-thirds of the world's population could be living under water stressed conditions. OECD predicts that overall water demand is to increase by 55% between 2010 and 2050, due to rowing demand from manufacturing, energy generation and domestic use. 

The water-energy nexus brings together two of the biggest development and human health challenges facing the world today. There are 1.2 billion people who live without access to modern energy services and around 2.1 billion people who lack access to clean drinking water at home. Perhaps unsurprisingly some of the most water stressed regions in the world are also the most energy stressed – much of Africa and South Asia face these dual challenges.

IN SUMMARY:

  • Coal mining and water
  • Coal use and water
  • Resources
  • Water news
 

Coal mining and water

Mine operations work to improve their water management, aiming to reduce demand through efficiency, technology and the use of lower quality and recycled water. Water pollution is controlled by carefully separating the water runoff from undisturbed areas from water which contains sediments or salt from mine workings. Clean runoff can be discharged into surrounding water courses, while other water is treated and can be reused, such as for dust suppression and in coal preparation plants.

Acid mine drainage (AMD) 

Acid mine drainage (AMD) can be a challenge at coal mining operations. AMD is metal-rich water formed from the chemical reaction between water and rocks containing sulphur-bearing minerals. The runoff formed is usually acidic and frequently comes from areas where ore – or coal mining activities - have exposed rocks containing pyrite, a sulphur-bearing mineral. However, metal-rich drainage can also occur in mineralised areas that have not been mined. 

AMD is formed when the pyrite reacts with air and water to form sulphuric acid and dissolved iron. This acid run-off dissolves heavy metals such as copper, lead and mercury into ground and surface water.

There are mine management methods that can minimise the problem of AMD, and effective mine design can keep water away from the acid generating materials and help prevent AMD occurring. AMD can be treated actively or passively.

  • Active treatment involves installing a water treatment plant, where the AMD is first dosed with lime to neutralise the acid and then passed through the settling tanks to remove the sediment and particulate metals.
  • Passive treatment aims to develop a self-operating system that can treat the effluent without constant human intervention.

Coal use and water

At the power generation end of the coal-energy cycle, new technologies are also reducing coal’s water footprint. As with other forms of thermal power generation, water in coal-fired plants is used in different ways depending on the type of cooling technology employed. Many technologies do not actually consume significant amounts of water but it is important to make sure that the extraction and return process minimises impacts on water temperature and wildlife.

There is a range of new technologies under development that significantly reduce the need for water in cooling systems and advances in dry cooling technology are beginning to have an impact.

Eskom, South Africa’s largest electricity provider, is a leader in dry cooling technology. This is crucial because South Africa is a water-stressed country. Eskom is currently constructing two new dry-cooled plants at Medupi and Kusile that are incorporating lessons learned from their older plants that already consume approximately 19 times less water than an equivalent wet-cooled power plant.

Resources

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Shenhua Group Water Management Programme

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Anglo American eMalahleni Water Reclamation Plant

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PT Adaro Making Water Work