Battery Energy Storage System Monitoring Technology, the Driving Force behind the Increasing Penetration of Renewable Energy – A Growing Presence Spurred by the Emergence of the Electricity Demand-supply Balancing Market
2023/01/25 Toshiba Clip Team
- Battery Energy Storage System plays a key role in electricity supply-demand balancing, essential for the roll-out of renewable energy.
- The appropriate monitoring technology can assess the condition of Battery Energy Storage System.
- The “Balancing as a service” that monitoring enables can help achieve carbon neutrality.
In July 2020, torrential rains swept through western and northern Japan, and in the following month a temperature of 54.4C was recorded in California’s Death Valley, the highest ever recorded on the planet. Will these kinds of extreme weather events become the norm? As climate change makes weather more variable and unpredictable, it is essential that we achieve carbon neutrality, which means reducing net emissions of greenhouse gases to zero. A key part of that effort is the promotion of renewable energy, such as wind power. As such, many companies are rushing to respond.
Unlike oil and other fossil fuels, renewable energy does not run out and does not directly emit CO₂. The drawback is that it depends on weather conditions, and its provision of power can be unstable. What is needed is a Battery Energy Storage System (BESS) that adjusts the amount of electricity by taking in and drawing out from the system, and it is vital that battery system and its batteries used are appropriately monitored for malfunctions and defects.
Toshiba has a number of battery monitoring technologies. How will these technologies enable the adjustment of electric power and the roll-out of renewable energy, and lead to a world where people can enjoy peace of mind? We spoke to Takahiro Kase and Kenji Mitsumoto from Toshiba Energy Systems & Solutions.
Addressing carbon neutrality with BESS-based electricity Demand-supply Balancing
With its basic policy of Generate, Transfer, Store and Use Smartly, Toshiba Energy Systems & Solutions helps underpin how our society functions. Takahiro Kase, who heads the company’s electric power distribution service business, explains this policy as follows.
Takahiro Kase, Senior Manager, Grid Service Business Creation Department, Grid Aggregation Division,
Toshiba Energy Systems & Solutions Corporation
“‘Generate’ electricity refers to power generation. Toshiba has been engaged in the provision of power generation equipment for many years, and is also developing renewable energy sources such as biomass, wind, solar, hydro, and geothermal. The ‘Transfer’ part involves Transmission & Distribution for smooth supply of power through distribution equipment and monitoring and control systems for power grids. Finally, ‘Store’ and ‘Use Smartly’ is where our BESS comes into play. We have also started a Virtual Power Plant* (VPP) business to link these areas together.”
*A system in which IoT devices remotely control distributed energy sources and make them function as if they were a single power plant
As the movement towards carbon neutrality picks up momentum, conventional energy supplies are being reevaluated. Renewable energy is becoming increasingly prominent as a replacement, but the amount of power that it generates is not stable, being subject to variations in environmental conditions. One idea is to store all surplus electricity in BESS once and then discharges only what is used, but Kase points out that this is “not very realistic at the moment.”
“A method by which all electricity generated from renewable energy can be stored and used when needed is possible if the price of BESS decreases considerably and their capacity expands many times over. Something like this will eventually become a possibility as BESS technology continues to develop. However, we believe that right now, where BESS has an important role to play in the power grid is in the electricity Demand-supply Balancing. As such, the development of a market for electricity Demand-supply Balancing will encourage the roll-out of renewable energy.”
The point to bear in mind is the frequency of the electricity supply. In western Japan, it’s supplied at 50 Hertz, and in the east 60 Hz. Whatever the frequency, it must be maintained. If it’s not, home appliances and factory machinery will not work properly, and generator operation will become unstable. At worst, it can result in large-scale power outages. A major source of disruption is an imbalance between demand, the electricity consumed, and supply, the amount generated.
This is why some generators are operated with surplus capacity to Demand-supply Balancing. They regulate the electricity generation in response to increases and decreases in demand and fluctuations in renewable energy, maintaining a balance across the power grid (the flow of electricity supplied from power plants to consumers, including generation, transmission, conversion, and distribution). This is how supply-and-demand adjustment works.
Electrical equipment does not work well if a balance is not maintained between power generation and demand
However, running thermal power generation facilities in this inefficient way in order to adjust Demand-supply Balancing result in unnecessary CO₂ emissions. “That is why we are pinning our hopes on BESS to achieve clean power adjustment,” says Kase. In other words, when there is an imbalance, electricity is momentarily transferred to and from BESS to restore the balance of supply and demand. This is called a BESS for Demand-supply Balancing, and Japan is expected to see increased deployment of such systems in the future.
To speed up this process, a Demand-supply Balancing market started operation in Japan from April 2021. Since its opening, businesses offering to adjust capacity with BESS can enter the market, and it is natural that the profile of BESS for power grids are increasing in prominence.
Toshiba produces the SCiB™ rechargeable lithium-ion battery. It is ideal for electricity Demand-supply Balancing because of its long service life and rapid charging and discharging. There is no doubt that the SCiB™ has a role to play in the transition to carbon neutrality. “Even if other companies are hesitant to use BESS for supply and demand adjustment, we are prepared to take the risk and move forward,” says Kase emphatically. “In fact, alongside the SCiB™ business unit, we have been developing SCiB™ models that can support supply and demand adjustment and withstand high output and high voltages, and we are conducting feasibility studies in Japan and overseas.”
The SCiB™ rechargeable lithium-ion battery, widely used for applications that include automobiles and industrial equipment
Maximizing performance by using multiple monitoring technologies to diagnose BESS
Toshiba’s strengths don’t stop there; it also excels in monitoring technology for assessing the condition of BESS. Kenji Mitsumoto, who works in the Energy IoT Department, in the same division as Kase, explains.
“It’s a fact of life that batteries degrade with continual use. This also includes reduced charging capacity and increased heat generation due to higher internal resistance. If the extent to which a BESS has degraded can be monitored, it can be used consistently to the full limit of its service life, and its performance potential can be exploited to the full. We have several of these monitoring technologies, so we can use the appropriate diagnostic method for specific situations.”
Kenji Mitsumoto, Fellow, Energy IoT Department, Grid Aggregation Division, Toshiba Energy Systems & Solutions Corporation
“Our four main monitoring technologies are the Charging Curve Analysis Method, Battery Capacity Estimation Testing, the Deviation of State of Charge (DSOC) method, and the Voltage Deviation Method (VD).” These may be difficult terms to understand, but Mitsumoto uses the metaphor of a medical checkup to explain.
“It’s a bit of a forced analogy, but Charging Curve Analysis is like the blood tests or ultrasound scans taken during a routine physical examination. For the test, the BESS is given what we call a test-specific charge, a charge with defined characteristics, and the in-depth data from that is used to diagnose the factors behind any degradation. It gives a precise diagnosis of the extent and causes of health problems.
As the name suggests, a Battery Capacity Estimation Test literally measures a BESS’s capacity. The amount of power that a BESS draws when it is charged from empty to full after being fully discharged is its charge capacity, and the reverse is its discharge capacity. In terms of a health checkup, this would be the equivalent of measuring a person’s weight and waist. The actual test takes several hours to a day, so it is not an easy measurement to perform like weighing someone on a pair of scales.
DSOC can be thought of as an estimate of weight condition based on the amount of exercise one normally does (distance or time spent jogging or walking) and one’s heart rate before and after exercise. If a person exercises at an appropriate level and monitors heart rate relaxation afterwards, it can be used for daily monitoring.
VD also uses everyday data, but it is unique in that a diagnosis can be performed regardless of whether the subject has exercised or taken a break. It is like a smartwatch that statistically processes pedometer and heart rate monitoring data to estimate health condition on a given day.”
When the Demand-supply Balancing market takes off, many operators, including those in renewable energy resource developer, will enter. BESS that suppresses frequency fluctuation by moving power in and out in precise and fast increments will be essential. If we were unable to visualize BESS’s condition and rate of degradation, we would never have the confidence to enter the market and put them into operation. That is why, in order to promote renewable energy and achieve carbon neutrality, Toshiba is putting so much effort into the monitoring of BESS.
BESS and monitoring technology work as a set to provide peace of mind and promote the roll-out of renewable energy.
The Demand-supply Balancing market, which launched in 2021, is gradually increasing the number of transactions. Given this, Toshiba aims to use IoT technology to provide the solutions vital for the next generation of electric power distribution. Kase, who leads services relating to electric power distribution, says, “with BESS, we’re talking about ‘adjustment as a service.’” As you may have already surmised, the idea is to provide a service that absorbs any disruptions in the electricity supply-demand balance by charging and discharging BESS.
BESS monitoring technology is also important for VPPs, which are expected to expand further with the emergence of the Demand-supply Balancing market. Again, VPP refers to distributed power generation and storage facilities that are remotely controlled by IoT devices in response to supply and demand conditions, so that they function as though they were a single power plant. So why does monitoring technology constitute a service? Mitsumoto gives us the specifics.
“In the future, people like owners of home-use BESS will join VPPs. However, if BESS is repeatedly charged and discharged remotely, some of them will degrade rapidly, and the owners will suffer. Therefore, a service that uses monitoring technology to show the condition of the BESS and provide a warranty for the amount of degradation could be provided. This monitoring technology holds all sorts of possibilities, and I think it will be used in many different settings,” he says.
For many years, Toshiba has been engaged in the operation of power plants and the monitoring of power grids. Of course, it also has a proven track record in renewable energy, while its SCiB™ rechargeable lithium-ion battery sees wide use in electric vehicles, industrial equipment, and frequency-regulating BESS. Then, there is its monitoring technology.
If extreme weather events caused by global warming, such as drought and severe flooding, become more frequent, neither our nor future generations will be able to live with peace of mind and security. As such, it is clear that carbon neutrality and more renewable energy are necessary to address this. Although the use of monitoring technology to assess the health of BESS may seem trivial at first glance, it is something we are working to implement as a solution to this problem.
* Note: Departments and titles are as at the time of interviews.