The first Power-to-Hydrogen-to-Power plant


Storing electrical energy through hydrogen conversion. This is at the heart of an ambitious European project developed in France: the first industrial Power-to-Hydrogen-to-Power plant fully integrated into an existing power plant application. An example of how renewable energies can be coupled with excess RES to produce and store zero-emission energy while stabilising the grid.

With a name meaning «Hydrogen as a flexible energy storage for a fully renewable European power system», Hyflexpower is an innovation project that is the first demonstration of an industrial Power-to-Hydrogen-to-Power plant. Implemented by a consortium led by Siemens Gas and Power, the project received funding from the European Union’s Horizon 2020 research and innovation programme and includes the participation of  Centrax, a British engineering company active in the gas turbine sector.

The Hyflexpower project

Peter MCCaig, project manager at Centrax Gas Turbines, who presented Hyflexpower at the Miac Energy 2022 conference, explains how the industrial Power-to-Hydrogen-to-Power plant is fully integrated into an existing power plant application, including a gas turbine with a low-emission system (DLE) with high hydrogen (H2) fuel.

The pilot site is an industrial plant in France, in Saillat-sur-Vienne, and is operated by Engie Solutions. This is a project, says MCCaig, in which the coupling of renewable energies can be demonstrated. It is an innovative and very interesting idea that allows, in practice, excess electricity to be stored through the process of electrolysis of water and re-electrification of the hydrogen produced in an existing thermal power plant that has been upgraded.

To realise the project, an infrastructure was developed with a hydrogen electrolyser, a hydrogen storage solution, a compression zone, and a mixing station.

The thermal power station, the manager continues, includes a Centrax CX400 package plant – which is planned to be upgraded to operate at up to 100 per cent hydrogen – equipped with a Siemens Energy SGT-400 gas turbine. The latter is an industrial gas turbine used in power generation and oil & gas applications. Its objective is to supply the site with heat and electricity, with a power output of up to 12 MW for this application. For this purpose, a pioneering supply and storage concept will be developed and installed, providing the industrial site with heat and power from renewable energy sources (RES).

How it works: from RES to RES

The project is designed to allow green energy to be harnessed for the needs of the industrial site, producing electricity and reducing emissions to zero.

Hydrogen, MCCaig explains, is produced through the process of electrolysis of water, generated in turn by exploiting excess flows from renewable energy sources – wind and photovoltaic – in the grid. Generally, these flows would remain unused or, again, the inability to store them would determine the need to reduce their production, while their transformation into chemical energy, precisely through the electrolysis of hydrogen, allows them to be stored in reservoirs. This hydrogen is then available to be electrified again and thus harnessed to produce energy when there is a shortage of wind or sun.

On days of higher energy production by RES or low consumption by the grid, the excess energy will be harnessed by the site to produce green hydrogen.

This will then be stored; storage takes place in pressurised tanks. The chemically bound energy in the hydrogen will then be converted into electrical and thermal energy in the SGT-400 gas turbine if required. Precisely to allow maximum utilisation of this mechanism, MCCaig points out, the gas turbine package, as mentioned above, will be upgraded to allow a variable supply from pure natural gas to 100 per cent hydrogen. The ultimate goal, which the project consortium aims to achieve in 2024, is to be able to validate up to 100 per cent hydrogen, demonstrating carbon-free energy production from stored renewable energy. Not only that, in this type of system the stored hydrogen itself becomes a load component that allows power supply fluctuations in the grid to be compensated and, consequently, stabilised.

The pilot project, moreover, was created for an industrial application, but is in fact replicable in other realities, and can therefore also be extended, says MCCaig, to large-scale storage and re-electrification concepts.

The project and next steps

Started in 2020, the first stage of the project was the installation of the hydrogen production site, which continued until 2022 with the installation of the gas turbine and the start-up of the plant with a mix of hydrogen and natural gas. In particular, MCCaig continues, a 30% hydrogen mix has been achieved, another goal the project consortium had set itself by 2022. The next step is to test using 100 per cent hydrogen in 2023. At the moment, Siemens in Germany is adapting its machinery for this phase: then the plant will be installed with a new gas turbine engine and tests for operability and operational stability will be carried out, using precisely no longer a mixture but 100 per cent hydrogen.

For the realisation of the project – which is worth 15 million pounds, or almost EUR 17 million – the consortium created for this purpose was made up of the three industrial companies involved – Siemens Gas and Power, Engie Solutions and Centrax – and a number of European universities that collaborated specifically in the study and analysis of combustion technology – Universität Duisburg-Essen, Deutsches Zentrum für Luft und Raumfahrt, Lund University, University College London, National Technical University of Athens and Arttic. Finally, economic, social and environmental impact assessments of the project are underway.

English heart

Centrax was founded in Newton Abbot in the UK – where it is still based today – seventy-five years ago, employs around 250 people and serves a diverse international market made up of a wide range of industries – including paper – and power applications. It provides complete power generation solutions, designing and manufacturing high-efficiency packages for power generation, in which it employs Siemens Energy’s gas turbine technology. Centrax’s packages cover a power range from 3 MW to 15 MW – implementing 85 per cent efficiency – and are primarily intended for combined heat and power generation, but are also used in base load, simple cycle and standby applications.

In addition to the construction, the company’s experienced technicians also follow the installation and maintenance of the systems, with the possibility of signing full maintenance contracts, offering support services that guarantee fast response times. Currently in the paper manufacturing sector, Peter MCCaig recalls, more than 60 sites in Europe have a maintenance contract with Centrax.