Technology Overview
Widespread adoption of renewable energy is at the center of our transition to sustainable energy around the world. Yet the increasing penetration of renewable generation imposes significant challenges on power system operation due to its natural uncertainty and variability. Energy storage systems (ESSs)—such as electrochemical batteries, pumped-storage hydropower, and hydrogen energy storage—can save energy from electricity for later use and respond instantaneously to unpredictable variations in demand and generation; therefore, they are promising to resolve various operational issues in power systems.
According to the U.S. Department of Energy Global Energy Storage Database, there are almost 1,700 operational energy storage projects around the world testing ways to integrate these technologies into existing and evolving electricity infrastructure. Few of these projects, however, are truly cost-effective commercial ventures. ESSs are still expensive to install. Value streams must be identified and appropriately monetized to make ESS a more financially competitive option to be adopted at scale.
Model, Optimize, Evaluate Energy Storage Systems with ESET
Electric utilities, legislators, regulators, ESS vendors, power market participants, energy customers, and researchers and developers need modeling and analytical methods and tools to understand how ESSs can be used in different use cases and the potential benefits. The lack of knowledge concerning energy storage capabilities and the ability to generate value from multiple applications results in an incomplete assessment of ESS value and becomes a significant barrier to ESS penetration in the marketplace.
To address this challenge, a research team from PNNL has developed a suite of five modules and applications that enable utilities, regulators, vendors, and researchers to model, optimize, and evaluate various energy storage systems. The software tool, called Energy Storage Evaluation Tool (ESET), examines a broad range of use cases and grid applications to maximize benefits from stacked value streams. The five modules that make up ESET are Battery Energy Storage Evaluation Tool (BSET), Microgrid Asset Sizing considering Cost and Resilience (MASCORE), Hydrogen Energy Storage Evaluation Tool (HESET), Pumped-Storage Hydropower Evaluation Tool (PSHET), and Virtual Battery Assessment Tool (VBAT).
Each module is used to evaluate different types of energy storage systems, including battery energy storage systems, virtual batteries from flexible building loads, pumped-storage hydropower, hydrogen energy storage systems, and storage-enabled microgrids. An earlier, far-less powerful version of the ESET module/app was launched in 2013 and has been licensed by 50 utilities, consultants, and vendors.
The current ESET version enables users to identify and appropriately monetize a broad range of value streams for various energy storage systems, thereby making energy storage a more financially competitive option to be adopted at scale.
Advantages
There are several other open-source and/or publicly available tools developed by national laboratories or non-profit energy research institutes to optimize and evaluate energy storage systems for targeted use cases. ESET is the most comprehensive of these tools. It evaluates a wider variety of energy storage technologies, and it models individual technologies in greater detail than other products.
For example, the battery storage evaluation module in ESET contains a high-fidelity, nonlinear model with dynamic operation range, as well as an advanced state-of-health model considering both degradation in performance and loss of life. Other energy storage valuation tools with modules for battery energy storage are based on simplified linear models with constant efficiency and static operating range. In addition, only the simplified loss of life model is used without considering degradation in performance and optimization of battery life.
ESET contains a set of modules and applications enabling a broad range of users to evaluate and size different types of energy storage systems for bundling grid and end-user services, including bulk energy, ancillary, transmission, distribution, and customer energy management services.
- Modules and applications model various energy storage systems with different levels of complexity and fidelity
- Easy to use without requiring knowledge of the modeling and optimization behind the tool
- Appropriate formulation and solution methods are selected or developed based on the energy storage systems and applications of interest
More comprehensive and powerful ESET modules are available for a licensee.
State of Development
The PNNL team partnered with local and regional utilities, as well as vendors, and used ESET to evaluate more than 30 energy storage systems across the country. Examples of these types of analyses included
- A lithium-ion battery storage system that was part of a smart grid demonstration project: The system was underutilized, operating an average of 14 hours per month for primary frequency response, with annual benefits estimated at $264,000. System operation optimized with ESET for multiple use cases simultaneously revealed a potential additional $170,000 of value available annually.
- A Massachusetts microgrid that added energy storage at one of its three sites: An ESET analysis indicated that a 441-kW 1-hour battery paired with 386-kW photovoltaic solar array can generate $2.5 million in present value benefits from stacked value streams, yielding a 1.16 return on investment ratio. In addition, forming a microgrid generally improved system survivability.
- Battery storage for a regional utility’s electric grid on a northeastern U.S. island: ESET analysis showed that the present value benefits for a 6-MW lithium-ion battery storage system, along with upgraded combustion turbine, are estimated at $145.9 million, yielding a 1.55 return on investment ratio. The majority (75 percent) of the benefits are tied to deferring the investment in a new submarine transmission cable.