SEQUENCING OF COAL PHASE-OUT IN ELECTRICITY SYSTEMS

1. Meaning and Purpose

Sequencing of coal phase-out means the planned legal, technical and economic order in which coal-fired electricity generation is reduced and ultimately removed from the power system. A lawful phase-out cannot be treated simply as closing coal plants on a fixed date. Governments must coordinate plant retirement with replacement generation, transmission reinforcement, storage, demand flexibility, workforce transition and security-of-supply measures.

Great Britain illustrates this approach. Government policy ultimately brought the deadline for ending unabated coal generation forward to 1 October 2024, accompanied by an emissions-intensity limit of 450gCO₂/kWh. The final coal-fired station at Ratcliffe-on-Soar closed in September 2024.

2. First Stage: Restricting New High-Carbon Capacity

An orderly coal phase-out normally begins by preventing the electricity system from becoming locked into additional unabated coal investment.

The Energy Act 2013 established the Emissions Performance Standard (“EPS”), which imposed an annual emissions limit equivalent to approximately 450g CO₂/kWh for baseload generation. Government explained that unabated new coal generation would normally emit substantially more than this level.

This regulatory stage reduces future coal dependence before existing stations are retired.

3. Second Stage: Developing Replacement Capacity

Coal retirement must then be coordinated with adequate replacement resources. Renewable electricity, nuclear generation, interconnection, storage, flexible demand and dispatchable capacity may all contribute.

The legal principle is sequencing rather than abrupt withdrawal. Security of supply remains an important statutory and regulatory consideration. Significantly, the Energy Act framework permits modification or suspension of the EPS where an electricity shortfall, or significant risk of one, arises.

This demonstrates that decarbonisation rules are designed alongside reliability safeguards.

4. Third Stage: Progressive Retirement

Older and less efficient coal stations can then close as environmental standards tighten and alternative capacity becomes available.

Plant age, emissions, profitability, reliability and network location may influence closure sequencing. The transition should also consider whether simultaneous retirement of geographically important stations could create congestion or regional adequacy problems.

R (ClientEarth) v Secretary of State for BEIS [2021] EWCA Civ 43

Facts: The case concerned development consent for up to 3.8 GW of new gas-fired generating capacity at Drax. Two existing coal units at the site were expected to be decommissioned, with proposed gas units using part of the existing infrastructure.

Legal Issue: Whether the Secretary of State lawfully interpreted national energy policy when consenting new fossil-fuel generation despite climate and carbon considerations.

Judgment: The Court of Appeal dismissed ClientEarth’s challenge and upheld the development consent decision.

Legal Principle/Ratio: Energy planning policy permitted the decision-maker to consider the continuing system need for dispatchable generation during the transition to a lower-carbon electricity system. Judicial review concerns the legality of the decision-making process rather than the court substituting its preferred generation mix.

Significance: The case illustrates the sequencing problem directly: retirement of coal may legally coexist with temporary or transitional reliance upon other dispatchable technologies where policy regards them as supporting system reliability.

5. Fourth Stage: Managing Environmental and Carbon Constraints

The transition must also comply with environmental assessment, air-quality obligations and climate legislation. Coal plants face increasingly restrictive emissions requirements relating to carbon dioxide, sulphur dioxide, nitrogen oxides and particulates.

In the High Court proceedings preceding ClientEarth, the court noted that substantial generation capacity was expected to close because of stricter environmental standards and ageing power stations.

ClientEarth v Secretary of State for BEIS [2020] EWHC 1303 (Admin)

Facts: ClientEarth challenged the Secretary of State’s consent for replacement gas generation at Drax, where coal units were scheduled for closure.

Legal Issue: Whether the Secretary of State had lawfully applied national policy concerning need, carbon emissions and electricity-system transition.

Judgment: The High Court dismissed the challenge.

Legal Principle/Ratio: National energy policy may lawfully balance climate objectives against the recognised need for reliable generating capacity, provided the statutory and policy framework is correctly applied.

Significance: Coal phase-out decisions therefore form part of a broader legally supervised transition rather than an isolated plant-closure exercise.

6. Fifth Stage: Social and Regional Transition

Sequencing also has a just-transition dimension. Coal regions may depend upon power stations for employment, local tax revenues and supply-chain activity. Closure planning can therefore involve site redevelopment, worker retraining and replacement investment.

Ratcliffe-on-Soar illustrates this post-closure stage. Local planning arrangements have been developed to facilitate redevelopment of the former power-station site following its 2024 closure.

7. Conclusion

The sequencing of coal phase-out requires coordination between decarbonisation, security of supply, environmental regulation, infrastructure investment and social transition. A robust legal sequence typically restricts new unabated coal, creates replacement capacity, tightens emissions standards, retires existing plants progressively and manages affected workers and regions. UK law demonstrates that coal phase-out is therefore not simply a prohibition on one fuel; it is a carefully governed restructuring of the electricity system in which climate obligations and reliability must be implemented together.