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RICAS2020 Report Summary

Project ID: 654387
Funded under: H2020-EU.

Periodic Reporting for period 1 - RICAS2020 (Design Study for the European Underground Research Infra-structure related to Advanced Adiabatic Compressed Air Energy Storage)

Reporting period: 2015-06-01 to 2016-11-30

Summary of the context and overall objectives of the project

Challenges like climate change, economic and social development, human well-being, sustainable development and security are closely linked to the energy supply of European societies. In 2009, the European Union adopted a ‘climate and energy package’ including that at least 20% of EU gross final energy consumption and at least 10 % of transport final energy consumption have to come from renewable energy sources and a reduction in primary energy use until 2020. As a consequence, the demand for technologies and resources for providing and storing adequate, sustainable and cost-efficient forms of energy is consequently increasing, but renewable energy sources like Solar and Wind energy fluctuate on a temporally basis and require highly applicable energy storage technologies.
Compressed Air Energy Storage (CAES), where compressed air is stored in underground caverns, is a well-known option of energy storage and the only currently feasible large-scale energy storage technology apart from pumped hydrostorage. The only existing CAES plants are diabatic ones, where fuel is added in the discharging phase. The Adiabatic CAES, where no fuel is added in the process has been studied as pure green storage alternative and has some very interesting advantages. The Adiabatic CAES Method is designed to deliver higher efficiencies via a zero-carbon process to an efficiency of about 70%. Nevertheless, research on this method contends with difficulties like the geological restriction to salt domes.
RICAS2020 - European Underground Research Infrastructure for Advanced Adiabatic Compressed Air Energy Storage - will meet this challenge by providing an innovative design concept of an Underground Research Infrastructure to develop technologies related to Advanced Adiabatic CAES by which the storage of very high amounts of “green” energy will be more sustainable and efficient. The big advantage of the new design concept will be the independence from the encountered geological conditions. Energy will be directly stored at all places where high energy demands exist.
RICAS2020 will provide unique research opportunities for companies as well as for research institutions to contribute to this demand which is also of great interest for a variety of research fields in underground engineering. RICAS2020 will be located as an extension of the independent research infrastructure “research@ZaB” in Eisenerz, Austria, which is financed by the Austrian government and designed as a European underground research-, training- and test-facility.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Within the first reporting period the following activities have been carried out:
• Design of the complete plant layout and operating conditions of an AA-CAES plant;
• Research regarding the thermal interaction between the surrounding rock or soil, the lining materials behaviour and the pressure of the stored compressed air;
• Research on completely new resource-efficient environmental friendly excavation and cutting technologies for rock and soil, to be able to build large underground storage caverns even close to highly populated areas without producing noise and vibration;
• Research on dimensioning large underground storage caverns in various ground types using powerful 3D-numerical simulation tools which will be evaluated with underground 1:1 scale tests;
• Research on new economical advanced materials resistant to the extraordinary high pressure conditions and high temperature;
• Research regarding new principles for equalization of working pressures during compression and expansion of gases for substantially increased efficiency of air storage cycles;
• Research regarding operational safety aspects for high-pressure storage of inert gases in underground structures;
• Research on Modelling of compressed air flows;
• Research on System integration.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Alternative energy sources namely Biomass, Geothermal, Hydro, Ocean, Solar and Wind energy have many advantages such as reduction of CO2 emission and relative accessibility. However, there are technological restrictions and difficulties: in electricity systems, supply and demand have to be balanced in real time. Therefore, every electricity system requires sufficient power plants to be able to meet maximum electricity demand. Electricity demand furthermore fluctuates on a temporally basis. In these connections, energy storage technologies become very important. Currently the most mature is Pumped Hydro Energy Storage. However, this technology has its own disadvantages such as geographical limitations and the need of a great space requirement on the surface. A good alternative is a Compressed Air Energy Storage (CAES). CAES refers to the compression of air to be used later as an energy source. Energy is stored during periods of low energy demand (off-peak), for use in periods of higher demand. Advanced Adiabatic Compressed Air Storage (AA-CAES) is an evolution of CAES, designed to deliver higher efficiencies via a zero-carbon process. The main idea is to collect the heat produced by compression and return it to the air when the air is expanded to generate power. The heat can be stored in a solid such as concrete or stone, or in a fluid such as hot oil or molten salt solutions. In practice, round trip efficiency of AA-CAES is expected to be 70%.
Benefits of AA-CAES in the sense of RICAS2020 are:
• no CO2 emission,
• it does not use any fuel for heating the air in expansion process,
• efficiency is higher compared to conventional CAES (up to 70%),
• reduced temperature and pressure fluctuations in the storage cavern.
Newertheless, AA-CAES has crucial restrictions such as dependence on geology (salt or porous rocks), geographical limitations (underwater air bags) or need large areas on surface to install the cisterns and tanks. RICAS2020 will help to overcome these factors which impose limits on the applicability of the AA-CAES technology. One of the main outcomes of the research in the underground infrastructure will be an opportunity to store compressed air in an underground storage cavern in any geological formation, which means in future AA-CAES facilities could be implemented wherever required, for instance very close to big cities or other high capacity energy consumers. RICAS2020 designs an unique research infrastructure which provides opportunities for companies as well as for research institutions to contribute to this demand which is also of great interest for a variety of research fields in underground engineering.

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