Fossil Fuel Transition Means Retirement for Many Coal-Fired Power Plants

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Earlier this month, leaders at the UN’s COP28 Summit announced a deal to transition away from fossil fuels, with a goal to achieve net zero carbon emissions by 2050. Prior to this deal, many developed nations across the world had already begun efforts to reduce carbon emissions, though these clean energy initiatives have not necessarily targeted fossil fuels in a broad sense. Rather, most nations have prioritized reducing their use of coal, as it has the highest carbon emissions among any fossil fuels. Here, we’ll look at the declining use of coal for energy generation and related trends.

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Coal-fired power plants are steadily retiring

Many wealthy nations throughout the world have significantly reduced coal power over the last decade, with several European nations, the United States, Chile and Israel posting the largest reductions. To put this rate of change in perspective, in the US about 20% of electricity generation is currently derived from coal, down from about 50% in 2007. And this trend is expected to continue for years to come, as the US Energy Information Administration (EIA) projects that 23% of US coal-fired capacity will be retired from 2022-2029. In just 2023 alone, the US was expected to retire 15GW of coal-fired energy generation capacity.  

This trend can be attributed both to competition from renewables and natural gas, as well as stricter environmental regulations. But there are some big exceptions, such as China and India, both of whom are adding coal-fired power generation capacity even as much of the world scales back. As the COP28 deal shows, there is a global consensus that reducing reliance on fossil fuels is a necessity, but there is a lot of disagreement about how exactly to meet emissions reduction goals. Indeed, the clean energy transition has been met with resistance, much of which is due to fears related to economic impacts. Developing economies are unwilling or unable to afford more costly renewables, and see coal as their only viable means of keeping up with growing energy demand. In places where coal-fired power plants have been in operation for a long time, communities and business interests fear that closure of coal mines and power plants will result in job losses and declining revenues for coal-producing regions. There is also some concern that fossil fuel phaseouts are outpacing the growth of renewables, which may mean less grid reliability for consumers. So, while we can expect that coal-fired power plants will continue to close, the pace at which they do so will likely depend on policies and programs that minimize these types of disruptive negative impacts.

Fossil fuel regulations are getting tougher

The declining use of coal is driven in large part by new policies. Regulatory agencies have increasingly adopted both “carrot” policies that promote investment in cleaner energy through tax breaks or other incentives, and “stick” policies that discourage polluting activity through fines or other punitive measures. Recently, the US Environmental Protection Agency (EPA) has been making more use of the latter, particularly with new operating standards for fossil-fuel fired power plants proposed earlier this year.

Under new EPA standards, coal-fired power plants will need to take steps to mitigate air and water pollution. Depending upon the design and generation capacity of the plant, these steps may include retrofitting the facility with carbon capture equipment, co-firing with 40% natural gas, replacing 96% of coal with hydrogen fuel, and/or running at reduced capacity. The timeline for making these changes ranges from 2035 to 2040, and plants that do not comply will need to commit to retiring by 2030. The cost of achieving compliance with these new standards is high—high enough that retirement will be the most economical choice for many coal-fired facilities. According to a report by IEEFA, a total of 173 coal-fired plants in the US are expected to close by 2030, and another 55 by 2040. Those that do remain in operation will need to meet the new air and water pollution mitigation standards.

Coal ash ponds are a target for regulators

One area of particular focus for the EPA in recent years has been coal ash ponds. These structures commonly serve as receptacles for storing wastes generated from coal combustion. Known as coal ash, these wastes can contain various heavy metals and other toxic constituents. New regulations for safe disposal of coal ash became effective in 2016 under the Resource Conservation and Recovery Act (RCRA), which established restrictions on where coal ash landfills and ponds could be located, and created standards for design, inspections, groundwater treatment and monitoring, closure, and reporting requirements. One of these requirements is that coal ash ponds need to be equipped with an impermeable liner to prevent toxic contaminants from leaching into groundwater. When these standards went into effect, coal-fired plants were allowed to file permits for extra time to make the necessary changes to comply. However, beginning in 2022, the EPA began to ramp up enforcement by rejecting permit extension applications, and ordering facilities to cease dumping ash in unlined ponds. Facilities who plan to retire by 2028 are exempt from the new rules.

Due to tighter regulations, coal-fired plants who plan to stay in operation will need to remediate and/or close their unlined ponds. This process will generally require that water in and around the pond be removed and treated. Because of the complexity of coal ash, a facility will typically require a wastewater treatment train that can consist of various steps, including physical/chemical separation, biological treatment, reverse osmosis (RO), chemical softening, ion exchange (IX), and/or membrane filtration. Resulting solid wastes can be disposed of in a landfill, and remediated ponds can be capped off.

Renewable energy and water impacts

Much of the water that’s consumed for energy generation is used for cooling purposes. While the amount of water used to produce each MWh of electricity will vary depending upon the type of cooling system in place, coal tops the list at around 1100 gallons of water per MWh of power produced. In fact, since the US began to replace its coal-fired energy capacity with natural gas and renewables over the past decade, power sector water withdrawals have declined gradually, according to the EIA.

Renewables do generally require far less water than coal, although exactly how much varies by the energy source, and other factors. Here, we’ll briefly describe some key renewable energy sources and their respective water impacts:

Biomass energy

Biomass is a type of renewable energy fuel that uses organic material derived from plants or animals.  Biomass fuels are generally grouped into three categories:

  • Wood is the oldest type of fuel, however, its use was largely supplanted by the rise of coal and petroleum over the last 200 years or so. Even so, wood pellets continue to be used, especially for heating, and the wood pellet industry is still growing in parts of the southeastern US.
  • Biofuels: Biofuels are mostly used for transportation. This group includes include liquid fuels, such as ethanol and biodiesel, that are produced by chemically converting plant or animal material through a chemical process.
  • Biomass waste. Biomass wastes can include solids from municipal landfills, as well as waste residues from agriculture. In some cases, landfills and sewage treatment facilities also capture and use biogas—the waste product from decomposition—as a fuel.

All of these are used to fuel thermoelectric energy production through combustion—in essence, these materials are burned, and the resulting heat is used to produce electricity. According to the US Energy Information Administration (EIA), today in the US just under 5% of primary energy consumption is derived from biomass. While this seems low, biomass is the single largest energy source compared to all other renewables, accounting for over a third of renewable energy consumption.

The production of wood and biofuels requires moderately high water inputs for growing feedstocks, which can include corn, soybeans, canola, and livestock. Additional water inputs are required to convert feedstocks to biofuels, and to cool energy generation equipment. While biomass is technically a renewable source of energy since new feedstocks can be produced, it is not always considered a green or sustainable energy source due to high carbon emissions and high water use.

Solar energy

According to data from the International Renewable Energy Agency (IRENA), solar energy saw over $308 billion in investments in 2022, which accounts for over 60% of all renewable energy financial commitments worldwide. And for good reason, as photovoltaic (PV) solar emits no carbon, and uses very little water. Thermal solar, on the other hand, can have high water inputs depending upon the cooling mechanism used by the facility, but its use is rare in comparison to PV solar. In all, total average water input for all solar technologies is around 20 gallons per MWh, per a Solar Energy Industries Association estimate.

Of course, manufacturing photovoltaic cells for use in solar applications requires water usage, and it produces wastewater that will need to be treated. Waste streams can include rinse water, spent process streams, and sanitary wastewater from plant operations. Contaminants can include organics, fluoride or hydrofluoric acid, and silicon, among other constituents. A PV panel manufacturer may adopt several water treatment technologies to handle these streams. In areas of water scarcity, it’s also common for facilities to adopt zero liquid discharge (ZLD) systems. Still, the lifespan of a solar panel can be upwards of 30 years, so water used in manufacturing is minimal in consideration of the total energy output during its service life.

Wind energy

Wind energy is a close second to solar energy in terms of growth in investment and adoption in recent years. According to data from IRENA, global capacity for wind energy has more than tripled in the past decade, totaling nearly 900,000 MW in 2022. At virtually zero, wind also has the lowest water inputs for  all renewable energy sources.

How can SAMCO help?

SAMCO has over 40 years’ experience in the design and manufacture of water treatment systems for a range of applications within the power industry. Our separation and wastewater treatment solutions have helped our clients achieve goals like water conservation, process optimization, and regulatory compliance.

If you’re interested in learning about the best water treatment technologies for energy generation applications, we invite you to contact us. Our engineers will walk you through the process for developing a water treatment solution to meet your specific objectives. You can also request a quote to help you develop a realistic budget.

For more information, head on over to our blog to learn more about the role of water treatment in the energy sector. Some articles that might be of specific interest to you include:

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