Greener Upgrades blog series #15
What is peak shaving?
Peak shaving is a strategy aimed at supporting peak power demand when available power is restricted. When it comes to Battery Energy Storage Systems (BESS), this involves storing energy when demand is low and deploying the stored power when demand exceeds the available capacity from the primary power source, whether this be a grid connection or a generator package. In this blog, we investigate how BESS can effectively address capacity constraints associated with limited power availability, making it a valuable tool for ensuring a stable, resilient power supply.
Many facilities and projects encounter peaks in energy demand, driven by factors like time of day, HVACR equipment, heavy duty machinery or motor starts. When power demand surpasses the available capacity, it can lead to equipment malfunctions, decreased production efficiency, or even process disruptions. By integrating BESS into a power system to mitigate these constraints, we can enhance system flexibility, manage demand peaks, improve efficiency, reduce emissions, and optimise energy consumption.
How does this work?
We can talk about peak shaving in two ways.
1. In terms of a hybrid power system, using a BESS to downsize a generator.
2. A limited grid supply, using a BESS to help overcome a limited grid connection.
Peak shaving to downsize a generator package
The Problem: In many projects a generator is sized for large peaks in power, however this means the generator is often oversized for the normal running load of the equipment. The initial peak current drawn would trip a smaller generator so how can we get around this challenge? Take the example of a 750kW chiller, we could use a generator to cover the start up load of 580 amps but the remainder of the time run underloaded.
Aggreko Solution: Aggreko can address this issue by integrating a BESS with a downsized generator, ensuring the efficient operation of equipment such as a 750kW chiller. The BESS, in peak shave mode, allows the chiller to accommodate higher current during start up without the need for an oversized generator.
Benefits: This mode enables the generator to be downsized which immediately gives fuel and emissions saving. It also ensures that when the generator is running, the load is sitting at a higher percentage ensuring a more efficient consumption rate and improve equipment reliability.
Peak shaving for a limited grid supply
The Problem: A project is limited to a small grid connection during working hours the power demand is higher than the available power, the BESS is able to save stored energy at low load intervals and use them when the power is needed. For example, an EV charging site has a power connection of 125A but the peak demand from multiple EV chargers is greater than supply available.
Aggreko Solution: Aggreko can address this issue by providing a mid-size BESS. The BESS will enable this solution to work from a small grid connection by storing the energy during low demand periods and discharging the power when the power demand exceeds the size of the grid connection.
Benefits: This mode enables a virtual capacity to be available, this allows the downsize of generation or the use of a smaller available grid connection. In some instances,this will negate the need for an upgrade in capacity.
Why BESS is an effective solution?
- Avoiding costly grid upgrades: BESS can mitigate or eliminate the need for expensive grid upgrades.
- Rapid power delivery: BESS can provide power almost instantly, whereas generators have longer startup times
- Handling larger load steps: BESS can handle larger load steps whilst maintaining system stability
- Emissions reduction: BESS minimises emissions and reduces fuel consumption compared to a traditional generator setup
- Increased generator efficiency: Integrating BESS can enhance generator efficiency
- Energy security: By reducing dependence on the grid, BESS enhances energy security
Peak shaving and grid power
BESS can be used to avoid or limit consuming energy from the grid during high tariff periods to reduce energy expenditure. Some companies may also want to limit using grid power when carbon intensity is high. This is done by the BESS charging during off peak periods, and utilising BESS power when the tariff is high. In addition, a BESS can be used to prevent companies from exceeding their import capacity.
Renewable integration
If a site or project has renewable sources of energy available, BESS can help increase utilisation of renewable energy by storing excess renewable energy when it is not needed and discharging the power stored in the BESS when it is needed on site. This not only increases a sites renewable penetration but also adds resilience to an energy system and reduces reliance on grid or generator power.
Important considerations
To determine the most effective temporary power solutions for a peak shaving application it is vital to understand the anticipated load profile, including peak loads, base load, and any high inrush currents. It is important to always involve a product expert to ensure that the project is fully understood and that the solution is specified.
Conclusion
Battery Energy Storage Systems (BESS) offer a versatile solution for managing power constraints. Applications like peak shaving demonstrate their ability to optimise generator sizing in hybrid power systems, particularly when grid connections are limited. This leads to enhanced efficiency, improved resilience, reduced emissions, and minimised fuel consumption. In the face of persistent grid congestion and power shortages, BESS emerges as a critical tool for achieving optimal power balance.