INSATIABLE THIRST : How Coal Consumes and Contaminates Our Water

The 2008 Kingston coal ash spill in Tennessee, USA dumped 3.8 billion litres of coal ash slurry into the Emory River. Photo: Dot Griffith
One of our planet’s scarcest natural resources - safe, affordable and accessible water - is under threat from the coal industry. Vast amounts of freshwater are consumed and polluted during coal mining, transport and power generation. A typical 1000 MW coal plant in Indiauses enough water in one year to meet the basic water needs of nearly 700,000 people. Globally, coal plants consume about 8% of our total water demand. The coal industry’s thirst for water is particularly concerning given that some of the largest coal producing and consuming countries, including India, China, Australia and South Africa, already face water stress and are currently planning enormous build-outs of their coal industries.

Coal is also a major polluter. Every stage of the coal life cycle pollutes water with heavy metals and other toxins at levels that significantly harm humans and wildlife. Exposure to this toxic stew has increased the rates of human birth defects, disease and premature deaths. The impacts on wildlife are similar. Often colourless and out of public view, the contaminants from the coal life cycle are an invisible menace to our health and environment.

Part 1: A Vast Consumer of Water

MINING AND PREPARATION

During mining operations, enormous amounts of groundwater are drained from aquifers so mining companies can access coal seams. Surface mines withdraw roughly 10,000 litres of groundwater per tonne of coal. Underground mines extract about 462 litres of groundwater per tonne of coal. The amount of dewatering varies greatly depending on the depth of the coal seam and local hydrology and geology.¹ A series of proposed mega-mines in Australia’s Galilee Basin is projected to extract 1.3 billion litres of water – over 21/2 times the amount of water in the Sydney Harbour. This extraction will drastically lower the water table, rendering local wells unusable and impacting nearby rivers.²

After coal is mined, it is typically washed with water or chemicals to remove sulphur and other impurities. The US Department of Energy estimates that coal mining and washing in the US uses 260-980 million litres per day.³ These amounts would satisfy the basic water needs of 5 to 20 million people (assuming 50 litres of water per personper day). The strain on water resources can be significant since mines are often located in arid regions. Mining also causes severe and long-term pollution of water resources,which can trigger water scarcity even in water-rich countries. This is detailed in Part 2 of this factsheet.

COMBUSTION

Coal-fired power plants consume the vast majority of water used by the coal industry. Plants built inland require even larger amounts of freshwater. Coal plants are increasing the strain on freshwater resources at a time when climate change is already starting to affect water supplies around the world.

During the combustion process, coal is burned to boil water and convert it into steam. The steam is used to turn turbines, which power generators to produce electricity. Different types of cooling systems are used to cool the steam and condense it back into water. Almost all of the water consumed by coal-fired power plants is used for cooling systems.

THIRSTY COOLING SYSTEMS

The amount of water withdrawn from freshwater sources and consumed by coal plants varies significantly depending on the type of cooling system used and the location of coal plants. Coal plants with once-through cooling systems withdraw tremendous amounts of water with disastrous impacts to aquatic life. The process of sucking in vast amounts of water destroys an estimated 2 billion fish, crabs and shrimp and 528 billion fish eggs and larvae each year in the US as aquatic life is rammed against screens or sucked into cooling systems.

While most of the water withdrawn is discharged back into the original water sources, it is usually discharged at temperatures 5.6-11^°C hotter than when it was withdrawn. This “thermal water” kills aquatic life and ecosystems, which are extremely sensitive to small variations in temperature change.⁵

Coal plants with closed-loop or recirculating cooling systems withdraw far less, but consume more, water than plants with once-through cooling systems. These systems usually use large cooling towers to let ambient air cool the water. However, millions of litres of water can be lost through evaporation and must be replaced.

Less than six percent of coal plants worldwide have dry cooling systems, using air instead of water for cooling. These power plants use 75% less water than plants with recirculating cooling systems. However, dry cooling systems are expensive and energy-intensive. Power plants with dry cooling must burn more coal for operation, decreasing their efficiency and increasing CO2 emissions by up to six percent.⁶

ESCALATING WATER CONFLICTS

Situating coal mines and power plants in arid regions around the world has sparked serious conflicts over water. From 2001-2010, farmers in the Vidarbha region of central India fell deeply into debt as the government liberalised its economy, scaled back support for small farmers and prioritised the allocation of water for energy generation, mostly coal, over agriculture. The intense financial burden triggered over 6000 farmer suicides. Despite this tragedy, 71 thermal plants, which would consume two billion cubic metres of water annually, are in various stages of approval in Vidarbha.

India is steamrolling ahead with plans to construct hundreds of coal plants despite projections that national water demand will exceed supply within 30 years. The proposed coal plants would consume 2500-2800 million cubic meters of water per year.8 This would meet the basic water needs of people living in India’s six largest cities – Mumbai, Delhi, Bangalore, Hyderabad, Ahmedabad and Chennai (assuming 135 litres of water per day for urban dwellers).

The Chinese government plans to build 14 large-scale coal mining bases and 16 new coal power generation bases, predominately in western provinces, despite projections that China will face serious water scarcity by 2030. Greenpeace estimates that these coal power bases will consume 10 billion m3 of water annually (or roughly 1/6 of the annual volume of the Yellow River). Currently, water resources per capita in these parched areas are only 1/10th of the national average. Coal development would consume a significant amount of water that is now allocated for drinking, agriculture and wildlife.

In South Africa, coal expansion will exacerbate problems with water scarcity. There is already a projected 17% gap between water supply and demand. With 13 new coal plants proposed, this will only worsen the situation. Coal mining expansion is also water-intensive and will pollute scarce fresh water supplies.⁹ Coal expansion in the pristine, water-sensitive area of the Waterberg, in the north of the country, is a massive threat as the water is guaranteed for use by the coal industry, with no assurances for other uses such as agriculture.

The siting of coal operations in regions of water scarcity can affect their economic viability. If coal plants do not have enough water to operate, they can be forced to shut down. Hot weather may also warm water supplies used for cooling, reducing the electricity production of coal plants when it is needed most. These declines in production can cut into revenues and make it difficult for companies to service their debt.

PART 2: How The Coal Life Cycle Pollutes Our Water

MINING

Surface mining dramatically alters natural water flow, increasing flooding and jeopardising the safety of downstream communities. When open pit mines are constructed, trees and other vegetation are cleared from large tracts of land. Enormous amounts of earth are excavated and piled in mounds next to mines. When it rains, erosion clogs and pollutes streams, wetlands and rivers with tonnes of sediment. Rivers can become so choked with sediment that they can no longer be used for fishing or transport.

An estimated 3840 km of streams have been buried by mountaintop removal mining in the Appalachia region of the United States. The effects of these valley fills are irreversible. Communities living near mountaintop removal mining have suffered from increased rates of lung cancer and heart, respiratory and kidney disease due to their exposure to contaminated water. Researchers found that 4432 people in this region died prematurely from 1999-2005, largely due to drinking contaminated water.¹⁰ Communities also experienced a 26 percent higher rate of birth defects.¹¹

Acid mine drainage is one of the most serious impacts of coal mining. When water interacts with rock exposed by mining, naturally occurring heavy metals such as aluminium, arsenic and mercury are released into the environment. Acid mine drainage contaminates ground and surface water, destroying aquatic ecosystems and water supplies that communities depend on for drinking and agriculture. These impacts can occur long after a mine has been abandoned, and perhaps indefinitely.

A South African Water Ministry official publicly called acid mine drainage “the greatest environmental challenge ever.”¹² South Africa has nearly 6000 abandoned mines. Some estimate that nearly 200 million litres of acid mine drainage per day threaten to pollute the Vaal River basin.¹³

Since the impacts of acid mine drainage occur long after a mine has been abandoned, the liability and high clean-up costs typically fall on local governments and taxpayers.

PREPARATION

After it is mined, coal is typically washed with water or other chemicals to remove impurities such as sulphur, ash and rock. This process requires large amounts of water and can strain groundwater aquifers. The resulting wastewater is stored in slurry ponds. Some slurry pond dams are larger than the Hoover Dam, storing billions of litres of highly toxic wastewater.14 Coal slurry contains high quantities of heavy metals and organic compounds, which can cause cancer and harm the development of foetuses. Most slurry ponds are unlined, allowing chemicals to leach into ground and surface water.

Dams that impound slurry ponds are often built quickly without adequate protections to ensure their safety and structural integrity. When coal slurry dams fail, they can spill millions of litres of toxic coal sludge, poisoning land and contaminating rivers and streams. In October 2013, an earthen dam broke, releasing 670 million litres of coal slurry into tributaries of Canada’s Athabasca River. The spill contained high concentrations of arsenic, cadmium, mercury and lead, forcing the government to warn communities not to use the river water until the slurry passed downstream.15

TRANSPORT

BNSF Railway estimates that almost 300 kilograms of coal dust can escape from each car in a loaded coal train over a 600-kilometre journey. The coal dust contaminates air and can lead to black lung disease in humans. Coal dust can also contaminate waterways during rail transport, and through leaks in damaged coal barges and during the loading and unloading of barges.

COMBUSTION

Coal-fired power plants are the largest source of toxic water pollution in the US, considering the toxicity of the pollutants emitted. Wastewater from coal plants contains a number of heavy metals and other toxins, which harm and kill aquatic life and contaminate drinking water supplies.¹⁶

Coal plants generate millions of tonnes of heavy-metal contaminated waste each year. This waste is laced with arsenic, boron, cadmium, lead, mercury, selenium and other heavy metals. Coal combustion waste is usually stored in dry landfills or mixed with water and stored in unlined pits impounded by earthen dams. The use of unlined pits increases the risk of pollutants leaching into surface and groundwater and contaminating drinking water supplies.

Dry storage is a better alternative to wet storage. In dry storage the ash is put into a big landfill. The site must be covered in order to minimise the risk of toxic dust blowing off and water contamination from rainwater mixing with the coal ash. If the bottom of the landfill is not lined with strong impervious material, heavy metals are likely to leach into the groundwater.

Air pollution control systems significantly increase the amount of wastewater generated by coal plants by transferring pollutants from the air to water. This wastewater often contaminates groundwater and surface water with heavy metals at concentrations that harm wildlife and human health.¹⁷

IMPACTS OF COAL COMBUSTION WASTE

The toxins contained in coal combustion waste can injure all of the major human organ systems, harm the development of foetuses and children, cause cancer, and increase mortality. In the US, toxics have leached from coal ash waste and contaminated drinking water in over 100 communities. The US Environmental Protection Agency (EPA) found that, in some cases, the level of toxics leaching from coal ash is hundreds to thousands of times greater than federal drinking water standards. The agency also estimates that people living within one mile of an unlined coal ash pond have a 1 in 50 risk of getting cancer from drinking water from contaminated wells. This is over 2,000 times higher than what the EPA considers acceptable.

The impact of coal pollution on aquatic biodiversity has been severe. Coal ash pollution has been documented to cause deformities in fish and amphibians, reduce reproductive rates and wipe out entire populations. Coal combustion waste has caused an estimated US$2.32 billion in damages to fish and wildlife in the US. Highly toxic selenium is largely responsible for the damages.

The most dramatic impact of coal ash ponds occurs when they fail. The largest catastrophic failure of a US coal ash pond dam occurred in December 2008 in Kingston, Tennessee, dumping nearly 3.8 billion litres of coal ash slurry into the Emory River. Homes were destroyed and families were relocated as their lands were smothered with a toxic sludge. The political power of the coal industry thwarted attempts to regulate coal combustion waste until recently. ¹⁸

MERCURY

Burning coal releases toxic mercury into the air that then rains down into rivers and streams. This poison then accumulates in the food chain, eventually making its way into our bodies when we eat contaminated fish. Mercury is a powerful neurotoxin that can damage the brain and nervous system. Mercury is of special concern to women who are pregnant or thinking of becoming pregnant, since exposure to mercury can cause developmental problems, learning disabilities, and delayed onset of walking and talking in babies and infants.

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