We deepen into the monthly subject: battery electrical energy storage systems. This time, we have interviewed Gabriel García, member of CENER‘s Renewable Energy Grid Integration Department.
What recent advances in battery energy storage technologies would you highlight?
The sector of batteries has experienced a spectacular development these last decades. It has become one of the main actors in segments as important as electronic devices, EVs and renewable energies. The huge demand, mainly from the first two abovementioned sectors, helped the sector to achieve a great maturity and reduce costs. Moreover, the cost reduction will go on during next years, so new market niches will appear for batteries.
As it is a component always present in our lives, news on new and promising developments stirs up the interest of the public. Everyone wants to have batteries with longer autonomy and lifespan, lighter batteries that could be recharged in less time. The scientific community works to make progress in these aspects and to reduce costs, increase their efficiency and recyclability, and minimise the use of scarce resources and of the dependency on certain geographical areas, etc.
Particularly, one of the most expected advances is the development of solid electrolytes, as that kind of batteries can achieve a greater energy density. They also improve the safety in comparison to liquid electrolyte batteries and could reduce the recharge time to ten minutes. On the other side, batteries should reduce the use of cobalt, for humanitarian and economic reasons, among others.
There are numerous studies in this field and news on successful advances, but the thorough and feasible ones must be identified. Usually, there are very promising advances in labs but then they fail in the industrialization and scaling process and finally do not get a significant impact in the market.
What is clear is that the battery sector, particularly lithium batteries, has achieved a high level of maturity thanks to the development of EVs and other applications can get benefits from them. We are talking about a growing sector, with a wide range of reliable suppliers that has been able to scale battery installations to meet the expectations of on-grid applications.
What are the main challenges to integrate energy storage systems and renewable energies?
In the preliminary stage, the sizing of the energy storage project is one of the main challenges. It depends on several factors such as the estimated renewable resource and the possible planned business cases. Depending on that and other factors, the energy storage system will be decided, at this point it is when the most suitable technology is chosen. Lastly, we need to calculate the ideal dimensions depending on the aim of the installation, considering the economic return, estimated lifespan, environmental conditions, etc.
This process can fail if regulations or the market conditions change during the lifespan of the project. The uncertainties of a sector in development such as the renewable sector, together with the energy transition, are important challenges for the energy storage sector and its deployment.
What are the main benefits for the energy sector of the implementation of storage systems?
Energy storage systems can be very interesting for the energy sector. Firstly, for the electrical system, as they can be used to replace some services that were usually provided by other technologies. Due to the gradual reduction of the installed capacity of synchronous generators connected to the grid, other technologies must replace the necessary inertia with fast-response systems. Luckily, there are storage systems that, together with the suitable power electronics, can give a fast response and regulate the system. Moreover, electrical systems will become more and more flexible as renewable generation increases to meet the Energy & Climate National Plan 2021-2030, so energy storage systems will be necessary to carry out different tasks and to provide energy when needed.
Figure 1 | Classification of the different energy storage applications. Source: EASE
On the other hand, apart from some exceptions such as supercapacitors, where energy is stored as electrical power, most of the energy storage technologies need to transform electricity into another kind of energy −chemical, thermal, etc.− to store it. Although this requirement implies some energy losses during the process, in cases such as hydrogen, it opens the door to interesting applications in sector coupling, a matter of vital importance to carry out the energy transition of the European agenda. The possibility to interconnect different sectors: electricity, gas, heat & cold, and mobility, gives us the opportunity to make the best out of our resources, to opt for different revenue sources, to increase the global efficiency of the system and to stabilise the markets.
What is your vision of the future electric grid?
Lately, the electric grid has been transformed to successfully integrate a huge amount of variable renewable generation. This transformation is still going and has to continue to meet international climate plans.
According to the European guidelines, the transformation must be an opportunity to implement changes in the electric market design to get a reliable supply at a competitive cost for the citizens. The market must be improved to attract the necessary investments for the long-awaited energy transition.
Even though the electrical market is usually considered to be a conservative environment, as it is more concern for supply reliability, distribution and transportation companies are immersed in the duty to create a smarter and more flexible system. It is the only way to integrate many distributed generation systems and allow the participation of other actors such as aggregators and related services such as demand management or smart EV recharge.
Would you like to talk about any project related to electrical energy storage the CENER is involved in?
Now, we are taking part in a very interesting European project whose aim is to increase the electric grid flexibility thanks to the perfect coordination of different renewable generation sources, energy storage systems and loads. It is the OSMOSE project (LCE-04-2017 – Demonstration of system integration with smart transmission grid and storage technologies with increasing share of renewables). RTE leads 33 partners, including some of the main European TSO.
The project has 4 demonstrators, one is being developed in Spain and led by REE. It is going to be commissioned in the months to come, connected to CENER’s ATENEA microgrid infrastructure located in Sangüesa, Navarra, Spain.
Figure 2 | ATENEA microgrid installations at CENER
This demonstrator will operate connected to the grid and it will use an HFD that combines STATCOM, supercapacitors and a 1500V DC lithium battery system. It will also use the equipment available in the microgrid, such as renewable generation, a vanadium redox flow battery, among other storage technologies, together with a programmable load system.
The solution will provide different flexibility services −inertia simulation, frequency regulation, voltage control, etc.− and will be managed by a control system. CENER provides its experience in renewable energy integration and energy storage management to develop the control system. It has two main aims, on one side, to provide the demanded flexibility services, respecting the predefined priorities and, on the other side, to manage the power requirements of equipment, considering the degradation of the different technologies to maximise its lifespan.
Once the operation of the demonstrator is validated at the CENER’s installations, it will be moved to be deployed at a REE distribution grid in the Canary Islands. The idiosyncrasy of the Canary electric system makes it the perfect test bench to assess the effectivity of the different technologies.