In the electricity market, there are two main markets that play crucial roles in ensuring the reliability of power supply: the energy market and the capacity market. The capacity market is designed to provide revenue assurance for power plants and incentivize investments in new generation capacity to ensure there is enough electricity available to meet demand, especially during peak periods.
Energy Market:
The energy market is where electricity is bought and sold on a daily basis. Power generators offer their electricity at a certain price, and electricity consumers, such as homes and businesses, purchase electricity at varying rates based on supply and demand conditions. This market operates in real-time or near-real-time, and prices can fluctuate throughout the day based on factors like weather, demand patterns, and availability of generation resources.
Capacity Market:
While the energy market handles the immediate supply and demand of electricity, the capacity market focuses on securing future power supply. It is essentially a forward market that addresses the need for reliable power generation capacity in the long term. The capacity market ensures that there is sufficient installed capacity (power plants) available to meet electricity demand even during extreme situations or unexpected events.
In many regions, grid operators or regulatory bodies run capacity markets. Periodically, they conduct capacity auctions or similar mechanisms where power plants (generators) can bid to provide a specific amount of capacity over a certain period (e.g., a year) into the future. The capacity needed is determined based on the anticipated demand growth, system reliability standards, and reserve margins (extra capacity as a buffer for emergencies).
Capacity Payments:
Generators that successfully bid and commit to providing capacity receive capacity payments. These payments are often fixed payments made to the power plants for their commitment to be available and operational during the contracted period, regardless of whether they are called upon to produce actual electricity or not. Capacity payments help power plants cover their fixed costs, such as financing, maintenance, and operation, and assure them of steady revenue in addition to the revenue they earn from the energy market.
The capacity market and capacity payments serve several important purposes:
Encouraging Investment: Capacity payments create financial incentives for existing power plants to continue operating and for investors to develop new generation capacity. This helps maintain and expand the diversity of the energy mix, including traditional power plants and renewable energy sources.
Ensuring Grid Stability: By guaranteeing a certain level of available capacity, the capacity market contributes to grid stability and reduces the risk of blackouts or power shortages during periods of high demand or unexpected generator outages.
Supporting Base Load Plants: Base load power plants, which operate continuously to meet the minimum demand, benefit from capacity payments as they play a crucial role in maintaining system stability.
Integrating Renewables: Capacity markets can also be structured to accommodate renewable energy sources that might have intermittent generation patterns. By providing capacity payments, renewable energy producers can secure revenue streams and remain viable in the market.
It's important to note that the specifics of capacity markets and capacity payment systems can vary from one region or country to another, as they are shaped by local regulations, energy policies, and market conditions.