Megawatt-Scale Energy Storage Opens Up a New Range of Possibilities

03-Nov-2016 15:12:36

The changing market landscape is creating a growing demand for advanced storage systems, especially with regard to renewable energy inputs. Toshibas’ Battery Energy Storage System (BESS) does a lot more than make it possible to control fluctuations in frequency of wind and solar inputs. It automates voltage regulation, optimizes demand and supply, and provides reliable back-up in blackout or disaster situations. Little wonder this 1.2 MW battery storage unit is rapidly gaining favor with major utilities.

sahkovarasto-15_edit_v3.pngThe recent installation of BESS in Helsinki, Finland is a case in point. Helen, one of the leading energy retailers in the Nordics, has set up a pilot system to study and test optimal operating principles together with the local DSO, Helen Electricity Network, and Finland’s national TSO, Fingrid. The Finnish operators were looking for proven technology with an attractive price/quality ratio suitable for a smart grid environment. The Toshiba battery system supplied by Landis+Gyr has a rapid charging/discharging capability and a long 10,000-cycle battery lifetime which makes it ideal for smart grid infrastructure. Once the pilot is complete, BESS will become a permanent fixture in Helen’s renewable energy generation structure.

Mind the gap

Regardless of energy source, BESS makes it possible to better manage demand. This is because energy stored in the 13,440 Toshiba SCiB™ battery cell units and the 560 storage battery modules (SCIBTM Type3-23 Ah) during low demand cycles compensates for gaps between power set points and current generation during high load periods. The BESS is also equipped with two power conversion systems for storage batteries, a battery control and management system with HMI and a three-winding transformer for interconnected systems. The advanced control and management system ensures power is fed into the grid as needed within the desired range.

Whether loading or discharging, BESS takes into account aspects like the current temperature of battery modules, the state of charge (SOC), charge/discharge rate, the characteristics of the inverters and the status of the grid.

Effective frequency regulation

The volatility of the renewable energy sources necessitates the use of highly responsive tools to iron out frequency fluctuations and resulting network instability that could lead to operational disturbances in equipment connected to it. This makes primary frequency control one of the most important use cases of a battery energy storage system. BESS is able to counter frequency fluctuations because it can be charged or rapidly discharged in response to changes in grid frequency. When the need arises BESS is capable of providing full power within milliseconds, creating an effective intervention until alternative reserves can be ramped up. In Finland, utilities currently provide the disturbance reserve for the transmission system operator (TSO) Fingrid. The installation of BESS means a utility can extend the portfolio of its reserve power offerings and provide the TSO with a new, more flexible tool to improve grid stability.

Automated voltage regulation

In addition to frequency fluctuation, distributed renewable energy inputs can affect voltage, power factor, and reverse power flow. Existing voltage control systems, such as tap changers in distribution transformers, may no longer be sufficient where generation is connected to the feeder. Overvoltage situations also have a negative impact on the service life of electrical devices. This can cause higher technical losses and trigger feeder line/ transformer protection. In reverse proportion, undervoltage situations are potentially equally damaging. They can cause flicker, alter the operation of synchronous machines, or unintentionally trigger device protection. Installing BESS means distribution system operators (DSOs) can balance voltage fluctuation by absorbing or injecting power as the need arises. The ability of BESS to compensate enables the DSO to keep the power factor within given limits and minimize network losses. In Finland, this means DSOs can avoid penalty fees imposed by the TSO for exceeding approved deviation levels.

Optimized demand and supply

BESS can also be valuably employed to smooth peaks and lows in electricity demand. Its batteries can be discharged during peak load and the reverse applies when demand is low, when its batteries can be charged. In Helsinki, BESS is used to optimize the purchase and sale of electricity, or to “buy low and sell high.” During peak load, the energy stored in batteries can be sold at top prices and there is also no need to buy additional power on the energy market. When prices are low, renewable inputs can be stored until such time as prices rise again. Helen will be investigating further business potential and business models for energy storage utilization during the course of its pilot project.

Backup for blackouts

In cases of blackout or major failure, vital infrastructure has to be kept going. Telecommunications, data centers, and hospitals are obvious examples of services that could be severely compromised through loss of power. BESS is a highly effective solution in this scenario because the energy stored in its batteries is immediately available and can bridge the gap until alternative back-up reserves can be brought online.

The considerable benefits outlined above make it clear that an ever-increasing number of battery energy storage systems will be incorporated into smart grid solutions in coming years. Effective storage is key to optimizing use of renewables.

Other BESS projects in operation

Two large-scale BESS systems have been installed in two different substations belonging to the Tohoku Electric Power Co. in Japan as a counter-measure to deal with network stabilization issues (frequency variation) caused by the penetration of wind and photovoltaic generation. The first system is a 40 MW/20 MWh BESS in Nishi-Sendai Substation, in operation since February 2015. The second system is a 40 MW/40 MWh in Minami-Soma Substation, in operation since February 2016.

Two 1 MW/1 MWh BESS systems have been installed for Terna S.p.A. in Sardinia and Sicily, in order to increase grid stability with high RES penetration. Terna tested different technologies from a grid and module scale perspective and Toshiba’s SCiB technology was proved to be the best performing in terms of round-trip efficiency and aging (higher number of charging/discharging cycles).

One 500 kW/776 kWh BESS system has been installed for Gas Natural Fenosa in the Alcalá Substation in Spain to evaluate the batteries’ effectiveness in responding at times of peak demand, as well as their capacity to manage electricity supply in places with high temporary or seasonal electricity demand. This project will also evaluate the batteries’ effectiveness in terms of managing network fluctuations caused by renewable energy sources.

New BESS projects given go ahead

Two more BESS projects recently received the green light. The first was the result of a contract signed to provide a BESS system for an Italian renewable independent power producer, Enel Green Power s.p.a. It is envisioned that the 4 MW/1 MWh storage unit will be used to smooth the intermittent flow of power on a wind farm.

The second project in Tucson, Arizona, is more than double the size: Landis+Gyr will partner with E.ON Climate and Renewables and Tucson Electric Power (TEP) to provide a 10 MW energy storage system to help balance load and regulate frequency on the TEP distribution system. 

The global energy storage initiative is heading east

  • $ 44 billion to be invested in storage between now and 2024, with $8.2 billion flowing into the market in the final year of the period.
  • Worldwide, annual installation rates will have risen from just under 2 gigawatt-hours this year to more than 16 gigawatt-hours in 2024.
  • The top five markets, which also includes the United States and the whole of Europe apart from Germany, Italy and the U.K., will make up 71 percent of all storage installed.
  • By 2024, BNEF predicts annual demand for lithium-ion batteries for electric vehicles will hit 163 gigawatt-hours, or more than 10 times the capacity needed for stationary storage.
  • The real energy storage heavyweights in 2024 are expected to be India and China, installing 2.2 gigawatts and 1.8 gigawatts of capacity, respectively.
  • Lithium-ion has been the preferred technology to date and was used in 90 percent of utility-scale projects, based on power output, in 2015.
  • The Asia Pacific region will host a majority of the 45 gigawatts and 81.3 gigawatt-hours of non pumped-hydro storage due to be installed worldwide by 2024.

Visit our European Utility Week page on battery energy storage to learn more:

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Sources: Global Energy Storage Forecast, 2016-24, by Bloomberg New Energy Finance (BNEF) 

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