Since the 1970s, the Tennessee Valley Authority has been burning coal just west of Nashville at its Cumberland Fossil Plant in Stewart County.
The nearly 2,500-megawatt plant is the largest coal plant in the Tennessee Valley and the largest single contributor to climate change in the state.
TVA plans to retire both coal units at the plant no later than 2033, depending on how soon the utility builds new generation.
For this new generation, TVA has outlined three options: one combined cycle gas plant (gas plus steam engine), two simple gas plants, or solar and storage.
Individuals, entities or organizations have one more week to weigh in on this decision, as the public comment period ends on June 13. TVA recommends submitting them online or by email to nepa@tva.gov.
TVA chose the first option, which requires a pipeline that is already being planned, in its Draft Environmental Impact Statement.
In the draft, TVA said it made this decision because of “economic, reliability and environmental risks”, with the basis that a combined cycle gas plant would allow the utility to build solar reliably and retire the coal units early.
However, building a gas plant will harm the environment because burning fossil fuels causes climate change. Gas produces roughly half as much climate pollution as coal when considering reported greenhouse gas emissions. But government estimates only tally the emissions coming directly from combustion and ignore the emissions from extraction, transport and end use, which can impact the environment in other ways.
Natural gas is mostly methane. When oxygen is added to the odorless gas, it combusts and produces energy with the byproducts of water and carbon dioxide. For example, TVA’s Allen Fossil Plant, a natural gas plant in Memphis, emitted about 1.3 million metric tons of carbon dioxide in 2020 — or the equivalentof about 300,000 cars driven for one year.
But methane, which is 25 times more potent than carbon dioxide at heating the planet, can also directly leak into the atmosphere from pipelines — and researchers are just starting to estimate how much with satellites.
There are also economic concerns with building a new gas plant. The board of the Nashville Electric Service, TVA’s largest customer, came out against this plan largely for business reasons.
After the comment period closes, TVA will publish its final environmental review before the end of the year. Then, CEO Jeff Lyash will make the decision because the TVA Board, which has only five of nine president-appointed seats currently filled, voted to give him autocratic power in the matter.
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