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Keeping Up with Energy Storage

Solar and energy storage are a match made in heaven and a new report from the Solar Electric Power Association, “Electric Utilities, Energy Storage, Solar: Trends in Technologies, Applications and Costs,” takes a deep dive into the energy storage sector. The report uses information from the Department of Energy’s Global Energy Storage Database to analyze 215 distributed generation energy storage projects developed by or in partnership with utilities.

“Electric energy storage (EES) has the potential to provide services to the grid, utilities, and downstream customers by improving power quality, reliability and adding needed capacity. EES should enable more solar to be installed on the grid while reducing the operational impacts of this variable resource,” the report says. 

Terry Allison, a senior engineer at American Electric Power, said to SEPA researchers, Miriam Makhyoun and Mike Taylor, “Storage is absolutely necessary and it’s getting cheaper.”

According to a recent report from Navigant Research, the annual energy capacity of advanced batteries for utility-scale energy storage applications will grow from 412 megawatt-hours (MWh) in 2014 to more than 51,200 MWh in 2023, at a compound annual growth rate of 71 percent.

The highest growth and volume of sales of advanced batteries over the next 10 years will occur in Asia Pacific, according to the report.  Power grids in the region are relatively immature, and the grid infrastructure still needs much work in many countries.  This provides an enormous opportunity for the use of batteries on the grid as one method to balance the load with generation.

“While there are several chemistries suitable for large energy storage installations for the grid, the clear leader is lithium ion and its subchemistries,” said Sam Jaffe, principal research analyst with Navigant Research.  “Lithium-ion manufacturers have raced ahead in building manufacturing facilities, giving them considerable advantages in the ability to meet large-volume orders and utilize economies of scale in order to bring prices down.”

The report, “Advanced Batteries for Utility-Scale Energy Storage”, analyzes the global market for advanced batteries for large-scale grid applications. 

In related news, the first grid-scale iron-chromium redox flow battery was recently used to commission EnerVault’s long-duration energy storage system.  In May, the California Energy Commission and the U.S. Department of Energy (DOE) dedicated EnerVault Turlock, the first grid-scale iron-chromium redox flow battery deployed in the world. EnerVault designed and manufactured the long-duration, grid-scale energy storage system in Silicon Valley with a combination of private funding and research and development grants from the DOE and the Energy Commission.

Long-duration energy storage systems are emerging as the lynchpin to efficient operations for resilient grids as aging conventional power plants are replaced by higher levels of solar and wind, according to EnerVault. Interconnected to the distribution grid, EnerVault Turlock is co-located with a dual-axis tracking solar photovoltaic system in an almond orchard in California’s Central Valley.

EnerVault’s system is a 1-MWh, 250-kW system that was manufactured in partnership with New-York based Ascension Industries, who built the first prototype.  NORAM, a specialized engineering and process design firm, worked with EnerVault to scale production and commercialize the system, which is designed to continuously deliver full rated power for up to four hours.

EnerVault is promoting the wide-scale use of energy storage to enable the expanded use of renewable energy, make fossil fuel power plants more efficient, reduce the costs of grid infrastructure, and increase the reliability of electric service to commercial and industrial users. The company targets applications with demand for large amounts of energy and said that its approach is ideal for supporting renewables, peak shifting in commercial and industrial facilities, or enabling operation and increasing fuel efficiency in micro-grids.

Aerial view of the EnerVault Turlock demonstration project. Credit: Eddie Shvartzman/EnerVault

In the same month, on the same coast, Seattle, Washington-based UniEnergy Technologies (UET) announced commercial availability of its grid-scale energy storage system, called the Uni.System.  The company said its system is modular, factory-integrated (including power conversion), and “plug & play,” comprised of five 20’ standard containers requiring only a concrete pad and interconnection that provides 500 kWAC of power for 4 hours, with power up to 600 kWAC and energy up to 2.2MWhAC.

The product uses a new generation of vanadium electrolyte that was initially developed at Pacific Northwest National Laboratory with support from DOE’s Grid Storage program, said UET President and CEO Gary Yang, who believes that the product is a breakthrough because it has “double the energy density and much broader operating temperature range.”

Yang said that traditional vanadium redox flow batteries have advantages such as “superior safety, unlimited cycle life, long duration, and full use of the battery from 0 to 100 percent state of charge” but in addition to those benfits, the Uni.System is fully containerized and includes “integrated electrolyte tanks, field-proven large-scale stacks, and optimized controls and power electronics.”

The Uni.System helps integrate renewables onto the grid by providing buffering capabilities – both short and long duration – to smooth the intermittent nature of wind and solar power.  It also supports smart grids and micro-grids and meets other utility needs, according to the company.


Credit: UniEnergy Technologies

Speaking of integrating with the grid, S&C Electric Company recently announced its new PureWave SMS-250 Storage Management System, the latest in S&C’s portfolio of solutions to integrate energy storage to power systems. By providing a new building block with which to integrate energy storage to the grid, this new 250-kW storage management system offers more flexibility in how energy storage is implemented while also maximizing economic requirements, according to the company.

The product is currently in use in Field, British Colombia. The system, owned by BC Hydro, integrates a 1-MW sodium-sulfur battery bank to the power grid so that it can provide up to seven hours of back-up power should the power grid experience a disruption. The system also provides peak shaving on a daily basis.

Field is a remote mountain community that relies on a single 55-km overhead distribution line to deliver power from the substation in Golden, B.C. to the town. In this mountainous terrain, heavy forestation, difficult access, and adverse climate conditions result in frequent faults affecting reliability, according to S&C. The company said that the energy storage system alleviates this problem by automatically transferring Field’s electric load to battery power when the grid is disrupted.

On the technology front, Somerset, NJ-based NEI Corporation said that it is developing a lithium-ion battery where the electrolytes are dissolved in water instead of an organic solvent. The aqueous-based lithium-ion battery has the potential to eliminate the risks associated with lithium-ion batteries, where the organic solvents are highly flammable, according to NEI. In addition, aqueous-based lithium-ion batteries have the potential to significantly reduce cost, measured in terms of $/kWh, the company said.

The company explained that while the concept of a lithium-ion cell using a water-based electrolyte has been known and studied, a major limitation is the narrow electrochemical stability window for water, which restricts the cell voltage. For example, the electrochemical stability window for water is within the range of 0 to 1.25V; electrolysis of water occurs outside this voltage range. In contrast, organic solvent-based electrolytes are stable up to at least 4V. The lower the cell voltage is, the lower the energy density is, and consequently, water-based lithium-ion batteries have had low energy densities.

However, scientists and engineers at NEI Corporation have recently developed new materials concepts that can overcome the voltage stability issue of water-based lithium-ion systems. The innovations pertain to the composition and morphology of the materials used in the lithium-ion cell. The aqueous-based technology is being developed with funding from the Environmental Protection Agency’s Small Business Innovation Research (SBIR) Program.

The company said that it is now looking to partner with a battery manufacturer to co-develop, test and qualify the water-based lithium-ion batteries.

Credit: NEI Corporation.

Residential Energy Storage Taking Off, Too

Energy storage solutions are set to play a larger role in the German electricity market at solar generation continues to increase. German solar photovoltaic generation peaked at around 15 GW on 11 May 2014 – a record high that caused prices to sink briefly into the negative. “Balancing supply with demand in the grid presents operators with a significant challenge and leads to market price fluctuations. That is where storage solutions come into play,” said Tobias Rothacher, renewable energies manager at Germany Trade & Invest (GTAI).

While politicians and the media have focused largely on smart grids as a solution, a quiet revolution has been taking place in the photovoltaic industry, said GTAI.

“Many solar installations will have paid for themselves in the next couple of years and some will soon reach the end of their 20-year feed-in tariff contract,” said Rothacher, who advises and supports international companies planning to invest in Germany. With modern and cheaper battery technology now available, these owners are able to store excess power during the day instead of feeding it into the grid at low prices and buying it back at night when it is more expensive. This helps to reduce grid fluctuations and with feed-in tariffs set to fall this summer, it makes even more economic sense.

Market research company EuPD expects sales of solar power storage systems to rise in Germany to 100,000 units in 2018, up from 6,000 in 2013. It is a development that has not gone unnoticed by politicians with the Federal Minister for Economic Affairs and Energy Sigmar Gabriel calling for battery technology to be returned to its position as a leading German industry.

“A number of factors are coming together that will lead to a boom in PV energy storage solutions in Germany,” Rothacher said.

To help meet that need, German company Sonnenbatterie GmbH presented its “eco” battery in Munich at Intersolar. The company uses lithium-iron-phosphate technology coupled with “high-quality” electronic components, according to the company to produce what it said is a compact wall-mountable design that it sells at “highly attractive pricing.”


The basic version of the Sonnenbatterie eco has a capacity of 4.5 kWh. The system is wall-mounted and can be expanded modularly up to a maximum storage capacity of 13.5 kWh. As with previous generations of its products, the company said that the Sonnenbatterie eco is a ready-to-use complete system that includes intelligent energy management, online access via an app or the internet and pre-configured connections for additional applications, such as back-up power, heat pumps or CHP.

“In combination with a PV system, an operator can benefit from up to 80 percent self-consumption at constant production costs, which are already significantly below current electricity prices,” according to Christoph Ostermann, CEO. He said that the lower price reflects the economies of scale that the company was able to capitalize upon.

Saft also launched what it said is the world’s first long-term warranty extension option for domestic lithium-ion energy storage modules. The company said that its storage systems ensure the effective grid integration of solar PV at all levels from enhancing domestic self-consumption through to megawatt-scale installations that support the operation of large PV generation plant as an integral element of power networks.

Saft is now offering a warranty extension of up to 15 years for Synerion Storage Systems integrated into Bosch’s BPT-S 5 Hybrid intelligent energy management and storage solution.

In extended cycling in particular, Saft batteries maintain a high capacity, even after more than 7,000 charge/discharge cycles, according to the company. Saft’s domestic scale ESS solutions are based on its Synerion Li-ion battery modules, each of which delivers around 2 kWh energy and up to 4 kW power.

The Bosch BPT-S 5 Hybrid system, launched in 2012, integrates a solar inverter, an energy management system and Saft’s Synerion modules.

Credit: Saft

Off-Grid Battery Technology Also Improving

Trojan Battery is trotting out its new lines of deep-cycle batteries that featuring “Smart Carbon” technology, which addresses the impact of partial state of charge (PSOC) on cycling batteries in renewable energy (RE), inverter backup and remote telecom applications.  Smart Carbon is designed to enhance life and performance of Trojan batteries operating in PSOC.

Smart Carbon is a proprietary Trojan formula that provides improved performance when the batteries operate in PSOC, enhancing overall battery life in off-grid and unstable grid applications where the batteries are under charged on a regular basis, said Trojan. Along with increased life in PSOC, Trojan’s Smart Carbon provides improved charge acceptance and faster recharge in PSOC applications.

With batteries now being one of the most expensive components of RE, inverter backup and remote telecom systems, it is critical to maximize the life of the battery bank in order to reduce total cost of ownership.   Trojan understands that batteries used in these systems are regularly cycled at PSOC due to the intermittency of solar generation, an unstable grid or to minimize operating costs of a hybrid Charge-Discharge-Cycle (CDC) system.  Operating at PSOC can quickly diminish the overall life of a lead acid battery, which results in frequent and costly battery replacements.  

Trojan chose to add Smart Carbon first to its deep-cycle flooded batteries because flooded technology is the most widely used in off-grid and unstable grid applications globally due to its cycling performance, ability to withstand harsh conditions, widespread availability and economical price point.  

“Trojan’s engineering team has spent more than five years in research and development experimenting with many types of carbon to ensure the right formula to successfully address PSOC,” said Bryan Godber, senior vice president of global market development at Trojan Battery.  “While most carbon additive research has focused on VRLA batteries for start-stop automotive applications, Trojan’s focus has been on the addition of carbon to deep-cycle flooded batteries for stationary applications in off-grid and unstable grid locations.

Credit: Trojan Battery

Lead image: Update via Shutterstock

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