UNDERGY project

Technologies for the development of seasonal renewable energy storage using green hydrogen as part of a smart grid

Spain’s energy commitments require a widespread roll-out of renewable generation to achieve targets that are clearly defined in the Integrated National Energy and Climate Plan (PNIEC) for 2030, with a timeline to become 100% renewable by 2050. The current energy context framing the UNDERGY Project reflects the need for a large-scale storage system to manage electricity surpluses from renewable sources and provide supply security to the energy system. By simply having sufficient storage capacity, we will be able to manage the seasonal fluctuations in renewable energy.

The UNDERGY Project (UNDERground enerGY) will research the technological basis for improving the competitiveness of seasonal renewable energy storage using green hydrogen.

UNDERGY proposes activities to harness renewable energy by integrating renewable generation and high-capacity seasonal energy storage into a smart grid based on two levers:  

  • the underground storage of renewable energy using green H2.
  • the creation of an efficient energy management system.

The project fosters activities to harness existing gas and electricity infrastructure grids to achieve the necessary transformation into a 100% renewable distribution network. The penetration of hydrogen as a renewable energy vector and its underground storage are still at an early stage, lending strong innovative characteristics to this project.
The UNDERGY Project is being undertaken by a consortium led by Petroleum Oil & Gas España (Naturgy subsidiary) alongside another five companies: Gas Natural Comercializadora (Naturgy Group), Ayterra, Gessal, H2B2 and Técnicas Reunidas. The project is scheduled to last for 39 months, up until the end of 2024.

Furthermore, six benchmark research organisations are also involved: The National H2 Centre, the Geological and Mining Institute of Spain, the Polytechnic University of Madrid, the University of Salamanca, the Loyola University and Tecnalia, which have the complementary technology capability to undertake all the research activities proposed for the duration of the project.

El proyecto UNDERGY cuenta con un presupuesto total de 5.599.227,00 € y una ayuda de 3.490.674,75 €. Ha sido subvencionado por el Centro para el Desarrollo Tecnológico Industrial (CDTI), en el marco de la convocatoria 2021 del Programa MISIONES CIENCIA E INNOVACIÓN (Plan de Recuperación, Transformación y Resilencia), y cuenta con el apoyo del Ministerio de Ciencia e Innovación. La ayuda otorgada al proyecto cuenta con la financiación de la Unión Europea a través del Fondo Next GenerationEU.

UNDERGY Project structure

Six complementary research activities

Petroleum Oil & Gas España will lead the project overall, while also leading Grupo Naturgy two specific activities: Activity 2 (through Petroleum Oil & Gas España) and Activity 6 (through Gas Natural Comercializadora). To do so, we will receive support from the National H2 Centre, the Geological and Mining Institute of Spain, the Polytechnic University of Madrid and the University of Salamanca.

In terms of underground research, the project will focus on validating conversion of our Palancares gas deposit into an underground green hydrogen storage facility. To this end, various laboratory studies will be carried out on samples from the reservoir that may be extended to other reservoirs with similar characteristics in the future.

The goal of this activity, led by the company Gessal, is to research and determine the green hydrogen geological energy storage capacity in the peninsular subsoil, finally creating a tool to enable the study of potential sites and suitable geological structures (resources, feasibility, potential).

Petroleum Oil & Gas España will address the feasibility of green H2 storage on a pilot structure. A depleted natural gas field located in Aljarafe (Seville) will serve on a laboratory scale, to investigate the reactions of the mixture of gases (H2-CO2-CH4) and containing rocks. In addition to the feasibility of storing H2, the potential methanation that could occur in the subsoil due to the joint injection of green H2 and captured CO2 will be investigated. Finally, a 4D modeling of the pilot storage will be carried out.

Furthermore, the possibility of scaling the results obtained from this activity to the other depleted deposits with similar characteristics will be assessed.

Led by the company H2B2, the objective of the activity is to analyze the main technologies of the electrolytic process to produce H2 from the integration of different sources of renewable electricity generation and water qualities. The activity aims at the conceptual design of a new 20 MW electrolyser suitable for operating on large energy storages (geological type) and designed ad hoc to function under the operating parameters of renewable energy.

The goal for this activity, led by Técnicas Reunidas, is to research the possibilities of reconverting the gas installations of the pilot site for the use of hydrogen gas and the technical-economic optimization of the new necessary processes. Conceptual study and design validated in the laboratory according to an initial transition scenario in which mixtures of H2 (20%) and CH4 (80%) are managed, and a final scenario that will entail the specific design for the management of pure hydrogen gas (100 %).

The goal for this activity, led by Ayterra, will consist of evaluating the potential risks related to the storage of green hydrogen in the subsoil. Environmental, hydrogeological, geotechnical and geomorphological aspects will be addressed, including seismic hazard, taking into account the processes of electrolysis and gas transfer in surface installations (H2-CO2-CH4). It will include the design of an environmental monitoring network for a future operational phase.

Considering the potential for in situ methanation determined in the laboratory, the supply of CO2, the capacity to reduce emissions associated with pilot storage and the possible use of existing infrastructure will be evaluated.

The goal for this activity, led by Gas Natural Comercializadora, will consist of proposing an efficient integrated energy management system, combining renewable generation and seasonal storage of green H2. To this end, various technical-economic studies will be carried out against different scenarios of the energy system, pursuing the avoidance of discharges and the optimal use of the renewable resource, in which the degree of penetration of the renewable generation of the Integrated National Plan will be taken as a reference of Energy and Climate (PNIEC).
In addition, a Geographic Information System will be developed that will collect the seasonal storage capacity in the subsoil, as well as various relevant information on the energy system such as data on generation, demand, renewable resources, networks, etc.