Australia's energy landscape is a tale of two systems.. On one hand, we have the National Electricity Market (NEM), a vast network that stretches the eastern and southern shores. On the other, we have the South West Interconnected System (SWIS), a smaller but no less significant infrastructure serving Western Australia. Although both NEM and SWIS have the same objective—providing homes and businesses with electricity—these two systems work in distinct ways.
The NEM is the largest interconnected power system in Australia. It stretches from Port Douglas in Queensland to Port Lincoln in South Australia and across the Bass Strait to Tasmania. This makes it one of the longest interconnected power systems in the world. The NEM connects five regional market jurisdictions - Queensland, New South Wales, Victoria, South Australia, and Tasmania. It operates on a gross pool, energy-only market where the Australian Energy Market Operator (AEMO) co-ordinates the dispatch of generation to meet demand on a five-minute basis.
The SWIS, on the other hand, is the major electricity grid in Western Australia. It covers the area from Kalbarri in the north, east to Kalgoorlie, and south to Albany. It is a smaller network compared to the NEM but serves a critical role in powering the state's southwest. Unlike the NEM, the SWIS operates under a capacity market. It is designed to ensure there is sufficient generation capacity available to meet peak demand.
While both the NEM and SWIS are designed to deliver reliable and affordable electricity, their different structures and operating mechanisms reflect the unique challenges and needs of their respective regions. The NEM, with its vast coverage area and diverse energy mix, requires a high degree of coordination and flexibility. The SWIS, with its isolated grid and peaky demand profile, requires a system that ensures reliability even during periods of high demand.
The NEM operates on an energy-only market. This is where generators are paid for the electricity they produce, and prices are determined by supply and demand. This market design encourages competition and efficiency, with generators incentivised to produce electricity at the lowest cost. However, it also means that prices can be volatile, fluctuating with changes in demand and supply conditions. The NEM also has a high Market Price Cap and a Market Floor Price to manage this volatility.
In contrast, the SWIS operates on a capacity market. This is where generators are paid for having capacity available to produce electricity, in addition to being paid for the electricity they produce. This dual payment system provides a steady income for generators, reducing price volatility and encouraging investment in new capacity. However, it can also lead to overcapacity and higher costs for consumers.
Regulation also differs between the two systems. The NEM is regulated by the Australian Energy Regulator (AER), which oversees compliance with the National Electricity Rules. The SWIS, on the other hand, is regulated by the Economic Regulation Authority (ERA) of Western Australia, which enforces the Wholesale Electricity Market Rules.
The NEM covers a range of generation sources. These include coal, gas, hydro, wind and solar. This diversity helps to ensure supply reliability and resilience. Meanwhile, the SWIS has traditionally been dominated by coal and gas, but there has been a significant increase in wind and solar in recent years. The increase in renewables can be attributed to the state's abundant renewable resources and supportive government policies.
As we look to the future, both the NEM and SWIS face the common challenge of managing the transition to a cleaner, more sustainable energy system. This involves not only increasing the share of renewable energy but also ensuring the reliability and affordability of the electricity supply.
In the NEM, the rapid growth of wind and solar is putting pressure on the grid, requiring significant investment in transmission and distribution infrastructure. The market design is also being tested, with questions about whether the energy-only market can provide sufficient incentives for investment in new capacity and storage.
In the SWIS, the challenge is to integrate increasing amounts of wind and solar into a system that has traditionally been dominated by coal and gas. The capacity market provides a steady income for generators, but it also risks leading to overcapacity and higher costs for consumers.
Despite these challenges, there are also significant opportunities. The transition to renewable energy opens up new possibilities for innovation and economic growth. It also offers the chance to reduce greenhouse gas emissions and make the electricity supply more sustainable.
In navigating this transition, there is much that the NEM and SWIS can learn from each other. The NEM's experience with managing a diverse generation mix and promoting competition can provide valuable lessons for the SWIS. Conversely, the SWIS's capacity market and its approach to managing overcapacity and price volatility could offer insights for the NEM.
In conclusion, while the NEM and SWIS have their differences, they also share common challenges and opportunities. By learning from each other's experiences, they can both navigate the energy transition more effectively and ensure a reliable, affordable, and sustainable electricity supply for all Australians.