The structure of the UK’s electricity market continues to attract scrutiny, particularly during periods of high energy prices and increased reliance on global gas markets. A recent article from Energy UK reinforces a key point in this ongoing debate: marginal pricing, despite criticism, remains the most efficient and cost-effective way to run a modern electricity system.
For organisations navigating energy procurement and long-term planning, understanding how this system works is essential. It underpins not only wholesale electricity costs but also the wider dynamics of investment, supply, and system reliability.
What Is Marginal Pricing?
Marginal pricing is the mechanism used to determine wholesale electricity prices in competitive markets. In simple terms, electricity generators submit bids based on their operating costs, and the price paid across the market is set by the most expensive unit required to meet demand at that moment.
This means that even if a large share of electricity is generated from lower-cost sources such as wind or solar, the final price can still be influenced by higher-cost generation, typically gas-fired power stations.
While this may appear counterintuitive, it reflects how supply and demand operate in real time. Electricity cannot be easily stored at scale, so the system must constantly balance generation with consumption. Marginal pricing ensures that enough generation is available to meet demand at all times, even during peaks.
Why It Is Considered the Most Efficient Model
Energy UK’s position is clear: marginal pricing is not an arbitrary policy decision but a fundamental feature of competitive markets. It is widely used across OECD countries and forms the basis of pricing for many commodities beyond electricity, including oil and gas.
The key advantage lies in efficiency. By ensuring that the lowest-cost generation is dispatched first, the system minimises the overall cost of meeting demand. Higher-cost generation only enters the market when required, preventing unnecessary expenditure.
This approach also provides a clear signal for system operation. Generators are incentivised to run efficiently, and the market naturally balances supply and demand without the need for constant intervention. In this sense, marginal pricing supports both operational stability and economic efficiency.
Addressing Common Criticisms
Despite its advantages, marginal pricing has faced growing criticism, particularly during periods of volatile gas prices. One of the main concerns is that electricity prices can remain high even when cheaper renewable energy makes up a significant portion of generation.
This is largely because gas often acts as the “marginal” source needed to meet demand, meaning its cost sets the overall price. As a result, fluctuations in global gas markets can have a direct impact on electricity bills, even in systems with increasing renewable capacity.
However, Energy UK argues that alternative pricing models do not necessarily reduce overall system costs. In some cases, interventions designed to cap or adjust prices have led to unintended consequences, such as market distortions or increased subsidies.
This highlights a key point: while marginal pricing can produce challenging outcomes in the short term, it remains the most reliable framework for ensuring that electricity systems operate efficiently over time.
The Role of Renewables and Market Evolution
As the UK continues its transition towards a lower-carbon energy mix, the role of marginal pricing is evolving rather than disappearing. Renewable energy sources typically have low operating costs and are therefore dispatched first under the current system.
This has already contributed to a shift in how the market operates, with renewables increasingly setting the baseline for generation. However, until storage and flexibility solutions are fully developed, higher-cost generation will still be required to balance supply and demand during periods of low renewable output.
In this context, marginal pricing continues to play a critical role in maintaining system reliability. It ensures that backup generation remains available when needed, while still prioritising lower-cost, low-carbon sources.
Alternative Market Approaches
Zonal Pricing
Zonal pricing is one of the most widely discussed alternatives. Under this model, electricity prices would vary depending on location, reflecting regional supply and demand. Areas with strong renewable generation, such as wind in Scotland, could see lower prices, while more constrained regions may experience higher costs.
Supporters argue this would improve system efficiency and reduce the need for costly grid interventions, although it could introduce greater complexity for organisations operating across multiple sites.
Separating Renewable and Gas Pricing
Another proposal involves decoupling renewable energy prices from gas-fired generation. In the current system, gas often sets the overall market price, even when renewables provide a large share of electricity.
By allowing low-cost renewable generation to be priced independently, this approach aims to ensure consumers benefit more directly from cheaper energy sources. However, implementing this model would require significant market redesign and could impact investment signals for flexible generation.
Expanding Long-Term Fixed Price Contracts
There is also growing interest in expanding mechanisms such as Contracts for Difference and other long-term agreements. These contracts provide generators with a fixed price for the electricity they produce, helping to reduce exposure to short-term market volatility.
For organisations, this could translate into more predictable energy costs. While this approach supports stability, it typically operates alongside the wholesale market rather than replacing it entirely, meaning marginal pricing would still play a role in balancing supply and demand.
Geopolitical Pressures and Market Volatility
It is also important to view the current debate around electricity pricing in the context of wider global events. The ongoing conflict involving Iran has triggered significant disruption across global energy markets, particularly through impacts on oil and gas supply routes such as the Strait of Hormuz.
While marginal pricing is often criticised during periods of high prices, these spikes are largely driven by underlying fuel costs and geopolitical pressures rather than the pricing mechanism itself. In this sense, recent global instability highlights the importance of maintaining a market structure that can respond efficiently to changing supply conditions, even during periods of significant uncertainty.
For organisations managing energy costs, the continued use of marginal pricing reinforces the importance of a strategic approach to procurement and risk management. Wholesale electricity prices will remain influenced by the marginal cost of generation, particularly the role of gas in balancing the system.
At the same time, the growth of renewables and the development of new market mechanisms, such as long-term contracts, are creating opportunities to manage exposure to volatility. Understanding how these elements interact is key to making informed decisions.
Ultimately, while debate around market reform will continue, marginal pricing is likely to remain a central feature of the UK electricity system for the foreseeable future. Its ability to deliver efficient outcomes at system level means it continues to underpin both current operations and the transition to a more sustainable energy future.
