Hybrid Energy Storage System Gets First-of-Its-Kind Certification

Marking an important milestone in energy storage’s steady charge to become a key element in balancing variability posed by renewables, ACCIONA Energia has received a prototype certificate from DNV GL for a wind project that is integrated with a grid-scale energy storage solution.

DNV GL, an Oslo, Norway-headquartered global quality assurance and risk management company that also acts as a certification body, handed the certificate to the Spanish conglomerate at WINDPOWER 2018 in Chicago this May. DNV GL’s certificate demonstrates the safety, performance, and reliability of ACCIONA’s hybrid plant for storing electricity in batteries as part of a grid-connected wind farm at Barásoain in Navarra, northern Spain.

The Barásoain plant has a storage system that consists of two batteries that are located in separate containers. One is a fast-response battery of 1 MW/0.39 MWh, which is capable of maintaining 1 MW of power for 20 minutes, and the other is a slower-response battery, though it has “greater autonomy” of 0.7 MW/0.7 MWh, maintaining 0.7 MW for 1 hour, said ACCIONA. Both employ Samsung SDI lithium-ion technology. The energy storage technology is connected to a single 3-MW AW116/300 wind turbine that uses ACCIONA Windpower (Nordex Group) technology. According to ACCIONA, the wind turbine is one of five that make up the Experimental Wind Farm at Barásoain, which it has operated since 2013. ACCIONA manages the entire system using control software it developed in-house. The system is monitored in real-time by the company’s Renewable Energies Control Center (Figure 4).

Figure 4_WindFarm_Acciona
4. A hybrid wind-battery project. ACCIONA’s experimental wind farm in Barásoain, in northern Spain, consists of five wind turbines. One turbine is connected to a storage system that has two lithium-ion batteries. The grid-connected storage solution is designed to advance technology services aimed at improving the quality of the energy sent to the grid. It will also analyze ancillary services—which are necessary to maintain a continuous balance between supply and demand—and the energy supply shift to match the production to periods of higher demand, which improves the economic performance of the installation. Courtesy: ACCIONA

The certification milestone is important because while energy storage technologies are increasingly being deployed along with renewable projects at a grid-scale, a comprehensive standard that guarantees their safety and reliability is rare. The certification is designed to provide more certainty to industry, including technology designers and manufacturers, as well as auxiliary backers like investors, insurers, and government authorities, which often seek information about risk mitigation and cost controls, particularly for fledgling energy storage projects.

“Certifying new systems like ACCIONA’s grid-scale storage plant demonstrates that pioneering projects like this are meeting the required safety, performance and reliability standards and providing the industry with confidence in the quality of emerging new technologies,” said Kim Mørk, executive vice president, Renewables Certification at DNV GL.

According to Carlos Albero, global finance segment leader of DNV GL’s energy division, as well as providing a quality benchmark, the certification verifies ways a hybrid renewables-storage project can make money. “We’re not speaking about the batteries themselves,” he explained to POWER. “You are integrating the wind turbines with the storage platform, and at the end of the day, they have to work together.” Hybrid projects have the benefit of providing revenue streams from grid-related services, such as from frequency and voltage regulation. “So, these are the kinds of revenue considerations that will need to support storage projects in the future,” he said.

For ACCIONA, the certification is an important aspect of technology qualification that is necessary to understand and manage its own risk. “In the near future, the bodies involved in the approval and financing of storage systems worldwide will demand these certificates,” noted Rafael Esteban, CEO of ACCIONA Energy USA Global LLC. “ACCIONA also wants to be a pioneer in this area. By applying for certification from such a solvent entity as DNV GL, we can guarantee that our plant fulfils all the conditions to operate with full confidence.”

The certification process was carried out under the GRIDSTOR Recommended Practice (DNVGL-RP-0043), which DNV GL published in January 2016 (and updated in September 2017). The freely available practice, which was developed by an international consortium from 15 global organizations, is essentially designed to “close gaps” in existing standards by covering a broad range of energy storage technologies and applications using a system-level approach, and offering a clear and comprehensive structure. Its various recommendations were adjusted to match well-known references to standards and guidelines like the International Electrotechnical Commission IEC 62933 standard. In the future, “I’m surely thinking that this recommended practice will end up being a standard,” Albero said. “We would create a guideline on that to develop a market.”

According to DNV GL, about 200 guidance documents are available as part of the practice that can be applied to grid-scale energy storage systems or components. The latest update provides industry guidelines on cybersecurity, communication protocols, microgrids, conformity assessment including factory acceptance testing and site acceptance testing, warranty, decommissioning, tendering and procurement, bankability, residual value, and greenhouse gas emissions calculations.

Albero said the recommended practice will undergo constant updates, so developers who have previously certified projects under an older version of the recommended practice will need to recertify, which takes about six months. DNV GL, meanwhile, is now assessing awarding certificates for hybrid projects on the Australian grid, but it expects that as the industry grows, and storage gains a stronger foothold on the market, demand for the certification will grow.

Sonal Patel is a POWER associate editor.