Interview with XAVIER GRANADOS

Xavier Granados García is a Senior Scientist at the CSIC and a member of the Department of Superconducting Materials and Nanostruction at Large Scale. Since 1987, he has collaborated with the Superconductivity group at the University of Barcelona and subsequently at the Materials Science Institute of Barcelona since its foundation, contributing to the development of R & D & I activities in the field of Superconductivity and its Applications in the Large Scale Area of ​​electrotechnical systems, leading the activities in this area within the Research group. He is a member of the Catalan Society of Physics, the European Society of Applied Superconductivity, the Institute of Electrical and Electronics Engineers, the Cryogenic Society of America, the High Temperature Superconductors Modeling Workgroup, CSIC representative at the JP Energy Sorage European Energy Research Alliance and coordinator of the sub-program Superconducting Magnetic Energy Storage. He has participated in more than 30 competitive projects and contracts with companies and has contributed in more than 150 publications.

Within the framework of development and improvement of technologies associated with the energy sector whose objectives are set in the SET-plan, it is necessary to suggest guidelines and priorities that will guide the research and development effort and thus improve its efficiency. In the specific case of the EERA Joint Energy Storage Program, EERA JP ES, an extensive consensus has been sought in conjunction with other entities including associations, companies, entities with the capacity to develop regulations and, finally, with active participation, with interests or which are affected by both the social and economic consequences of the development of storage technologies.

In this complex task, the European Association for Energy Storage, EASE, complemented its effort with EERA JP ES, leading a roadmap that was published in March 2013 under the title “EASE / EERA Energy Storage Technology Development Roadmap towards 2030 “(http://ease-storage.eu/easeeera-energy-storage-technology-development-roadmap-towards-2030/). Over the years and the development achieved, a process of revision and updating has become necessary.

The revision of the road map, once made with the contributions of the members of EASE and EERA JP ES, has been submitted to a public information process in which the affected agents, the “Stakeholders”, have been able to suggest and comment in order to send their opinions to the editor. At the end of this period of public information, a meeting of “Stakeholders” was convened in which it was intended, and achieved, that the sections concerned could be discussed before being incorporated into the drafting in the final phase of discussion by the core editor.

It is important to note that in our country the first document has served as one of the references in the drafting of other documents in relation to the perspectives, technologies and impact of energy storage. In particular, the Inter-Platform Storage Group (GIA) has taken into account the “EASE-EERA RoadMap”. Both the form of its wording and its content and the variety of institutions and countries involved suggest that it is a useful reference.

EERA was established as a formal commitment between 10 European Research Institutes on 27 October 2008. Its origins are in the need of combining efforts and being able to contribute at the global level and in the first line following the objectives set out in the SET-plan, making it easier to achieve the targets set for 2020 and 2050 in terms of greenhouse gas emissions, energy efficiency and renewable energy development.

The Alliance seeks to combat the fragmentation and under-funding of the European R & D system by coordinating efforts between research centers.

From this idea the mechanisms of relationship and governance are defined and the structure of the Alliance is built on the basis of Joint Programs (JP’s) that combine the combined effort of research groups in specific areas. Within each joint program, sub-areas or subprograms (SPs) are defined, dedicated to a specific technology such as the JP of Energy Storage (ES) in which 6 SP’s coexist: Electrochemical Storage, Chemical Storage, Thermal Storage, Mechanical Storage, Magnetic Storage and Economic and Social Aspects of Energy Storage.

In 2011 the number of Allied Laboratories in the energy storage program was 26 out of 12 countries. From Spain, five institutions: CIEMAT, IMDEA, CNH2, ICMM and ICMAB.

The development and growth of the Alliance and the need for a firm structure, with legal personality that allowed it to have its own resources, meant a change in its social structure and a reorganization leading to the non-profit-making society EERA AISBL in 2014, with headquarters in Brussels. During the reform period, which ends in 2015, CSIC becomes a full member. At present, it is CSIC and not its Institutes individually that participates in the Alliance.

In the joint energy storage project four Institutes, Ceramics and Glass, Materials Science of Madrid, Nano-Science and Nano-Technology of Catalonia collaborate, and the Materials Science of Barcelona. The Alliance allows coordinating efforts with other centers in Europe, optimizing resources and promoting strategies as well as giving visibility to the relevance of the subject in particular and the options under development. Centers with limited resources such as ours can access technology and state-of-the-art knowledge and trends more easily.

In the Group of Superconducting Materials and Nano-structuring to Large Scale, one of the aspects in which it has had interest is in the development of its applications. This helps to understand and value the impact that the development and diffusion of the material can have in diverse fields like the one of the energy. This understanding has implications for the development of the material and for the development of the design tools and manufacturing methods of both the material and the device, ie the development of a specific engineering.

Participation in the Joint Energy Storage Program gives us a perspective of collaboration that would otherwise not exist. In the specific case of the development in which I participate, the SMES (Superconducting Magnetic Energy Storage) the encounter and joint work allows to improve the cohesion and the capacity and this, in itself, leads to a greater probability of success in the calls for financing . Europe is included in the race for the development of this type of systems that can be competitive because they cover, with simplicity, needs that others can not provide.

EASE is an association dedicated to the storage of energy from the point of view of providing an overview of the energy system with the inclusion of the concept of storage. Unlike EERA, it includes industrial partners. EERA not only focuses its effort on energy storage, this section corresponds to one of its Joint Programs and there are 17. In EERA, the partners are research institutions. The intersection between EASE and EERA is not null and limited to some members of the JP ES.

The collaboration between both associations is inevitable and one of the fruits is precisely the coordination of efforts through the RoadMap.

There are Spanish institutions in the two associations. In the case of EASE, institutions such as CENER and CIRCE are partners, but companies such as ENDESA, IBERDROLA, GAS NATURAL FENOSA and RED ELECTRICA DE ESPAÑA also participate. CSIC does not participate and ICMAB is part of CSIC

In the RoadMap, and in the EERA JP ES, the various technologies in development for the storage of energy are included. Many of them are hybrids in the sense that they convert one energetic vector into another. Storing electrical energy in the form of mechanical or thermal or chemical energy is a clear example, although not always the final destination has to be electrical energy. These processes, in general, allow storing a large amount of energy but the processes of interchange usually have weaknesses and limitations, which include delays in their availability, they need time to be active; degradation produced in the loading and unloading processes, which requires a good control of the conditions in which both processes are performed, or mechanical complexity in systems based on flywheels.

In the paper, according to the RoadMap, two directly electric storage technologies are considered: electric field (or Polarization, depending on the view) or magnetic field, ie electric voltage or electric current. The first case corresponds to the Super-capacitors while the SMES corresponds to the second. I have introduced the second technology. The storage in the form of magnetic field has, by contrast a great flexibility and its electromagnetic nature does not require reconversion, it is already electricity. In essence, it is a coil of superconducting material through which electric current flows without loss and generates a magnetic field. The use of superconductor allows the circulation of very intense electric currents without heating the coil and with this can reach very intense magnetic fields. From the point of view of stored energy, a cubic meter of 10T magnetic field (Tesla is the density unit of the field) represents an energy 30 times greater than that of a cubic meter of water at 100 meters in height.

These systems are not new in Spain. During the 1990s, a great effort was made to place superconductivity in Spain at a competitive level through a macro project, the MIDAS project, financed by a small fraction (less than 0.1 per thousand, if I am not mistaken ) of the electric bill. ASINEL, RED ELECTRICA, IBERDROLA and other companies coordinated part of this fund to finance conceptual and practical development projects, including the AMAS 500 project, led by ASINEL and IBERDROLA, among others.
The development of high-temperature superconducting materials since 1987 is a simplification of cooling systems since it is possible to think of operating temperatures above 4 K (-269 ºC) corresponding to the boiling of the liquid He used by systems based on low temperature superconductors. This is a further step in the viable development of these devices, regardless of the dependence with the He, and using more efficient, affordable and cheaper heat and cooling systems, so that large-scale commercialization would be possible.

Already in the present century, the occurrence of the superconducting tapes takes place, especially the calls of 2ª generation (2G) that have been a challenge of manufacture of materials very important from the point of view of functional ceramic coverings. In them the superconductor covers the 600 m of metallic tape (hastelloy, steel or NiW, according to the technology used) forming a textured layer, that is to say, the formed crystalline layer maintains its crystalline orientation along those 600m or more. That layer of one or two microns thick is the one that drives the 500 A per centimeter of width at temperatures as high as the boiling of Liquid Nitrogen.

With this type of materials the cooling is simpler and the thermal stability of the coil is higher. Given the industrial availability of LN2, LO2 and LCH4 as industrial gases and as energy storage systems, it is possible to make hybrid energy storage systems where SMES can be incorporated into the electronic system that is common to all storage. Together with the possible use of LH2 (Hydrogen liquid) as energy reserve, the SMES achieves a unique robustness and rapidity. Responds easily to power demands in times less than millisecond. Both its power and responsiveness, its efficiency and the unlimited number of unloading load cycles make it a key element in hybrid storage systems, giving them a large capacity to cover virtually all storage needs. In the background, it is nothing more than a coil and electronics, a bit sophisticated but nothing more. It can only be made with superconducting material.

Discovering is perhaps an excessive word. Since a few years, since 2010 essentially, it has been suggested that the use of superconductors in electric generators powered by wind turbines, windmills, could simplify the necessary mechanical structure and coupling. Especially in Off-shore mills, those installed in the sea. In this case, they could make viable the construction of mills of 10MW. To give you an idea, the mills that we see in the heaths of the hills and mountains of our geography usually have a power of about 2 MW and each blade measures around 60m. The whole, not counting the tower, comes to weigh between 200 and 300 tm.

The ability of superconductors to produce magnetic fields in excess of the somewhat less than 2T that can be achieved in conventional generators with iron-based magnetic circuit gives rise to two things. The first is that iron can be removed from the magnetic circuit: it drastically decreases its weight. The second is that the magnetic field is higher, which decreases the size or allows to generate the desired power at lower speed. In the wind turbine (windmill or wind generator) there are, basically, four elements: The turbine (the blades), the multiplier, the generator and the converter. The turbine rotates at a speed between 10 and 15 turns per minute and the conventional electric generator does at 1500 revolutions per minute, this necessitates a gearbox that multiplies the speed of rotation of the blades about 150 times. The multiplier is a heavy mechanical assembly, about 20 tm in a 2MW mill, and subjected to enormous mechanical stresses. Reducing the speed of the generator means a great simplification and lightening of the system that results in greater reliability, lower maintenance and lower cost.

The strategy followed with the research group led by Gamesa Innovation and Technologies SLU and the institutes of CSIC ICMAB and ICMA, has been different. Based on a partial funding from the Ministry, Project RTC-2014-1740-3 “DESIGN OF A NEW GENERATION OF GENERATORS AND AUXILIARY EQUIPMENT FOR WIND ENERGY BASED ON SUPERCONDUCTORS”, and the contribution of Gamesa. It has started from a Generator, of the type DFIG, of common use in the wind turbines of 2MW. In the first phase the standard cooling system has been removed, thus halving the total volume of the generator and replacing the copper and iron stator with a superconducting stator which generates the static field. The thermal sustainability of the assembly has been proven as well as the operation of the generator, within the limits of power that the test bench allowed, demonstrating the validity of the technology used and specifically designed. The possibility of obtaining the same power as the original generator (even greater) at a rotation speed three times lower has been demonstrated. In a second phase, pending co-financing, it is proposed to modify the rotor by eliminating the magnetic iron circuit making way for the possibility of systems with direct coupling. One of the aspects that has been verified is the economic viability of the system in production so it could be a surrogate generator of conventional systems in a new generation of machines of medium speed in which the reliability is greater, much lower weight and the losses by heating are evacuated with a simpler and reliable refrigeration system.

It remains to be done but the road is clear. Unfortunately it is difficult to have a reliable and continuous financing if the support of cofinancing should be made from projects that do not guarantee continuity despite the success of the first stages however we are hopeful to be able to continue advancing to see in operation this type of generators.

For the whole team, the success of the project has been an injection of optimism. Moving from calculations to reality is always a satisfaction, especially when experience in that technology is being forged. Our greatest satisfaction would be to go one step further and be able to turn the definite set into a commercial reality, possibly with more advanced versions with direct coupling although the mid-speed versions are economically viable in the framework of medium powers.

One of the points that seems to emerge from the existence and use of TRLs is to transfer to researchers the idea that what they are trying to develop has a future in the market. For many of us that idea may be new, but remember that there is a certain need for an advance of technology towards a commercial level.

Another thing is that ideas or basic studies must have room even though they are very far from the market. The point is not TRL but how many resources are devoted to each level. Remember old controversies about whether basic or applied research, the answer has always been: both.

The TRL in the calls depend very much on the state of the art in advanced solutions for each subject or type of technological requirement. New solutions have no place if the particular issue has existing options with high TRL. The question would be whether they should have a choice in that call or there should be calls for new technologies to be explored and that, evidently, have a very low TRL but can be intuited can lead to breakthrough solutions. This is a complex field in which one must face the risk that the proposal does not lead anywhere, but without abuse. The money of the calls is effort of the taxpayer, it should not be forgotten.