How Battery Energy Storage System (BESS) Solves Grid Instability?
- Posted On:
- November 20, 2024
- Category:
- services
Battery Energy Storage System
Battery Energy Storage System in Home Energy Systems
As more people worldwide increase their electricity consumption,
Electricity distribution companies face significant challenges related to grid instability.
Grid instability is when there are fluctuations in the balance between electricity supply and demand within an electrical grid.
This can cause disruptions, outages, or inefficiencies in energy distribution.
In a metropolitan area, the electricity demand significantly spikes during hot summer afternoons due to widespread use of air conditioning units.
As more people use electricity for cooling, the demand on the grid rises sharply.
If the existing infrastructure is not designed to handle these peaks, it can lead to overloading of transmission lines and substations.
This might cause power outages, where certain areas of the city lose power.
If the grid relies heavily on renewable energy sources like solar or wind, which can be intermittent (not consistently available), this further complicates stability.
For instance, a sudden cloud cover could reduce solar energy output at the same time demand is peaking, amplifying the instability.
Rapid fluctuations in energy demand can lead to outages and the need for additional power generation, especially during peak usage times.
Battery Energy Storage Systems (BESS) provide effective solutions to enhance grid stability and manage these challenges.
Let’s dig in!
Impacts of Grid Instability
When demand surges, existing transmission lines and substations may not be equipped to handle the increased load, leading to potential overloads. This can result in equipment damage or failure, further exacerbating the instability.
Overloaded infrastructure can cause blackouts, where certain areas lose power. This disrupts daily life and can impact critical services such as hospitals and emergency response systems.
Relying heavily on renewable sources like solar and wind can create complications, as these sources are not always available. For example, sudden cloud cover can decrease solar output precisely when demand is high, increasing the likelihood of instability.
Fluctuations in electricity supply and demand can cause voltage instability, which can damage sensitive equipment, appliances, and infrastructure, leading to increased maintenance costs and potential failures.
Utilities may need to invest heavily in upgrades to manage peak loads and avoid outages. These increased operational costs can lead to higher electricity prices for consumers, impacting affordability.
How Battery Energy Storage System (BESS) Solves Grid Instability?
Demand surge typically occurs between 3 PM and 8 PM during summer months when temperatures exceed 90°F (32°C).
As temperatures rise, usage of air conditioners can spike by 50-100% compared to off-peak times, resulting in a sudden demand increase of 20-30 GW across regional grids.
If the local grid capacity is 10 GW, a sudden surge of 20-30 GW can overwhelm the system, leading to potential overheating of transformers and subsequent equipment failures.
When demand spikes, the grid frequency can drop below the standard 60 Hz.
For instance, if the frequency drops to 59.5 Hz, it may trigger automatic protective measures that could result in rolling blackouts affecting thousands of homes.
How BESS Solves the Problem?
Before the BESS can start working, it has an initial state of charge (SoC), which indicates how much energy is stored in the battery pack.
Lithium-ion batteries battery packs are widely used in BESS due to their high energy density, long cycle life, and efficiency.
The lithium-ion battery pack stores electrical energy as chemical energy during the charging phase and releases it during discharging to provide electrical power to the grid.
Inside a battery pack, energy is stored chemically through electrochemical reactions.
During charging:
- Anions (negatively charged ions) and cations (positively charged ions) move between the anode and cathode, driven by the electric field created by the applied voltage.
- This process converts electrical energy into chemical potential energy stored in the battery.
Charging Process (Energy Storage):
The system receives energy from the grid at a specified power level.
- During charging, lithium ions (Li+) move from the cathode to the anode through the electrolyte, while electrons move through the external circuit.
- The anode typically consists of graphite (C\text{C}C), and the cathode is made of a metal oxide compound like lithium cobalt oxide (LiCoO2\{LiCoO}_2LiCoO2).
Oxidation at the Cathode
At the cathode, lithium ions are removed from the cathode material (lithium cobalt oxide) through oxidation, losing electrons. The oxidation reaction is:
LiCoO2→Li++CoO2+e−
- Li+is a lithium ion that moves toward the anode through the electrolyte.
- e – is the electron that travels through the external circuit to the anode.
Reduction at the Anode (During Charging):
At the anode, the lithium ions (Li+) and electrons combine to form neutral lithium atoms, which are intercalated into the graphite structure of the anode:
C+Li++e− →LiC6
Here, lithium ions are embedded (intercalated) into the graphite layers (LiC6).
Overall Reaction During Charging:
The net reaction during the charging process can be represented as:
LiCoO2+C→LiC6+CoO2
This stores electrical energy as chemical potential energy in the anode.
BESS systems, like those with a capacity of 500 kWh, can charge overnight (off-peak) when electricity demand is low, storing energy at a cost of approximately $0.05 per kWh.
During discharging
When demand peaks, the system sends energy back to the grid at a specified power level.
BESS can discharge energy at a rate of 100 kW, supplying crucial power to the grid within milliseconds.
When discharging, the process is reversed.
Lithium ions (Li+) move back from the anode to the cathode through the electrolyte, and electrons flow through the external circuit to provide power.
Oxidation at the Anode (During Discharging):
At the anode, lithium atoms are oxidized back to lithium ions and electrons:
LiC6→C+Li++e–
This releases lithium ions (Li+) back into the electrolyte and electrons (e -) to the external circuit to supply power.
Reduction at the Cathode (During Discharging):
At the cathode, lithium ions are reduced as they combine with electrons to form lithium cobalt oxide again:
Li++e−+CoO2→LiCoO2
This reaction completes the cycle, allowing the lithium ions to recombine with the cobalt oxide, restoring the cathode material.
Overall Reaction During Discharging:
The net reaction during discharging is the reverse of the charging process:
LiC6+CoO2→C+LiCoO2
This releases the stored chemical energy as electrical energy that can be used to power the grid.
Utilizing advanced algorithms, BESS can forecast peak load times, reducing the likelihood of grid overload.
If the BESS anticipates a peak load of 25 GW, it can discharge energy to mitigate the risk of exceeding the 10 GW capacity.
During discharge, the battery pack’s State of Charge (SoC) drops from its initial value (e.g., 100% to 20%) based on how much energy has been released. A 500 kWh BESS discharging at a rate of 100 kW could fully deplete its charge in about 5 hours if the entire capacity is used.
500 kWh BESS discharges 80% of its energy (400 kWh), it would require roughly 4-6 hours to recharge at an off-peak rate of 100 kW. Charging costs during off-peak hours can be as low as $0.05 per kWh, making the recharge cost approximately $20 for 400 kWh.
By balancing energy discharge and efficient recharging, BESS battery packs continue to provide stable power to the grid while maintaining their performance over many cycles.
Final Thoughts
Battery Energy Storage Systems (BESS) effectively mitigate grid instability by storing energy during off-peak times and discharging it during peak demand.
Utilizing lithium-ion battery packs and advanced Battery Management Systems (BMS), BESS helps maintain grid frequency, prevents overloads, and supports renewable energy integration.
This makes BESS essential for enhancing grid reliability and stability.
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