Generation
In order to ensure reliability of power systems, electricity generation and demand must be balanced at all times. For this, power systems operator put in place operating reserves and ancillary services that are capable of responding at different timeframe, from sub-seconds to hours, all of which are required to ensure grid stability. BESS can within a fraction of a second, responding to grid requirement by charging or discharging, making them a suitable resource for short-term reliability services, such as Primary Frequency Response and Regulation. BESS if sized appropriately, can also provides longer duration services, such as load-following and ramping services, to ensure supply meets demand.
Electricity demand fluctuates daily based on the economic activity at the load center, and can also fluctuates based on seasonality factors. For grid stability, a good power system operator will ensure that it is able to provide electricity supply during the highest electricity demand at any given period of time, or the peak demand. This is achieved with the installation of peaking capacity, conventionally with power plants such as gas fired power plants, which are able to start and synchronized to the grid within a short period of time. However, these gas plants are typically higher cost generators in the power generation mix and they produce greenhouse gases. BESS is now a viable option to provide such peaking capacity where if sufficiently sized, can provide equivalent peaking capacity as a conventional gas plant without emission of greenhouse gases. In this case, BESS is charged by the grid during off peak hours, and discharge energy to the grid during peak hours, ensuring reality of the power system.
To start-up large power generators, it requires external sources of electricity to perform key services such as cranking up of a turbine rotor, lube oil system operation and other cooling services, for these generators to reach operating speed and conditions, before they can start generating power to the grid. Under normal operating conditions, these start-up power can be imported from the grid. However, if there is a power system failure, these generators can no longer obtain this start-up power from the grid and will need to depend on an on-site source of power (typically large set of diesel generators) to perform a process known as black start. An on-site BESS can also provide this service, which is a viable alternative to diesel generator which requires periodic testing and maintenance. A BESS on the other hand requires very little maintenance, does not require fuel and will not emit greenhouse gases to the atmosphere. Furthermore, if engineered and designed properly, the same BESS can be used to provide additional frequency response support and other services to the grid, putting the asset in good use rather than a capex which sits at the plant waiting to react to an emergency that may never happen during the life of the power plant.
As a result of various technologies’ cost competitiveness and government incentives, the world is witnessing a steep rise in the installation of renewable energy power plants such as solar and wind to the grid. As renewable energy share in the total generation mix increases, intermittency of renewable energy plants to the grid can no longer be ignored. BESS is the perfect solution to act as renewables stabilizer as it charges during excessive renewable energy generation and discharges whenever there is a dip in renewable energy generation. The BESS flattens the curve!!