Electricity: the power-to-gas essential for a 100% renewable future Electricity: the power-to-gas essential for a 100% renewable future

By Bernard Reinteau, specialist journalist

In just a few years, the idea of ​​100% renewable electricity has taken hold. So much so that manufacturers offer technical solutions to the difficulties of frequency variation or energy intermittency.

All observers of the electric power world have heard the reversals of discourse over the past 15 to 20 years. Thus, we have gone from an impossibility of ensuring electricity production with renewable energies to a “proven technical and scientific feasibility”. A Webinar conducted by négaWatt at the beginning of April ⁽¹⁾ presented the latest advances on this important subject for the decades to come. How is an electrical system mainly powered by variable renewable energies technically possible?

One of the keys to the success of this transition is the development of power-to-gas, i.e. the combination of renewable energies and hydrolysis in order to optimize the use of renewable electricity by producing hydrogen which will be injected into the natural gas network or consumed to produce electricity.

Power-to-gas concept to contribute to 100% renewable electricity

The convergence of studies towards 100% renewable electricity

Spokesperson and longtime activist within négaWatt, Marc Jedliszka underlines the interest shown in this subject since the beginning of the 2000s. In Germany, the 2004-2007 Kombikraftwerk 1 study developed by the Fraunhofer IWES institute in Kassel aimed to prove the feasibility of a 100% renewable electricity system. This approach on a 1/10000th model showed that the balance was reached at all times without importing. However, important issues such as the quality of the wave and the stability of the network had not been addressed at that date.

The Kombikraftwerk 2 study from 2011-2013 – which concerns a complete modeling of the German high-voltage network – came to fill this gap with this conclusion: “Simulations show that an electricity supply with 100% renewable sources is technically possible in Germany in the future under good conditions of reliability and stability, provided that production, storage and backup interact intelligently with renewable gas. »

Other studies have come to similar conclusions. Marc Jedliszka recalls the 2015 ADEME study on a 100% renewable energy mix. Last November and January, Cired (CNRS) ⁽²⁾ returned to this subject. Its work on renewable electricity is based in particular on the hourly profiles of wind power and photovoltaics for the past 18 weather years (2000-2017) and on an estimate of the average cost of renewable energies of €52/MWh.

He also cites the REStable project piloted from 2015 to 2019 by Mines ParisTech to assess the frequency variations on the network of 12 wind farms and 5 photovoltaic farms: the frequency variations remain within the tolerance range of +/ -10%.

This fear of electricians should be put aside by the Migrate program ⁽³⁾ led by the National School of Arts and Crafts with Schneider Electric and RTE and other partners. The idea is to install equipment on the networks such as synchronous compensators to maintain 50 Hz with 100% renewable energy production. Finally, last January, a joint report by the RTE manager and the International Energy Agency ⁽⁴⁾ indicated to the Ministry of Energy Transition the "conditions and prerequisites" for creating an electrical system with a significant share of RE by 2050.

For Marc Jedliszka, a 100% renewable electrical system is therefore feasible, while respecting:

1. technical conditions, with in particular the use of solutions such as Power-to-gas to smooth production, the commissioning of asynchronous compensators to maintain power quality and industrial operation production forecasts;
2. regulatory conditions, because texts still need to be produced to move forward on this path;
3. and managerial, because collaboration is essential between the stakeholders.

He stresses that "in any case", it will be necessary to invest massively in the means of electricity production, nuclear or renewable, but it is now a question of taking into account the "spectacular drop in the production costs of PV and wind power compared to other "carbon-free" means of production", in the same way as the management of demand and production of electricity, batteries or Power-to -Gas. And to conclude: “Thus, refusing to embark on this path is not a technically and economically rational choice, but an ideological or political choice. ”.

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Webinar - Can the electrical system operate with 100% renewables – Négawatt webinar of April 7, 2021 – source Négawatt -

EnR helped by major energy managers

On the negaWatt side, this discourse is hardly surprising. It is in line with the white papers that this association of scholars regularly produces. Its 2017 scenario indicated electricity consumption falling from 431 TWh in 2015 to 305 TWh in 2050, and total energy consumption (heat, transport and electricity) falling by 55% (1830 TWh in 2015, 806 TWh in 2050 ). The update of this exercise is announced for fall 2021.

On the other hand, what may be surprising is the accompaniment of this discourse by a company such as Storengy. This subsidiary of Engie specializes in the storage of natural gas in underground geological sites (aquifers, salt cavities). The company ⁽⁵⁾ has 21 storage facilities in France, Germany and the United Kingdom, representing a capacity of 12.2 Gm³, the equivalent of 75 nuclear units.

Pierre Chambon, Managing Director of Storengy France, sees in the development of renewable electricity the opportunity for a new activity for his company: the storage of renewable gases which will participate in new methods of producing this energy. This is mainly biomethane from methanizers now widely distributed across the country, and hydrogen produced by hydrolysis powered by excess energy from photovoltaic and wind farms. This power-to-gas makes it possible to compensate for the intermittency of the installations: essentially storing the energy and supplying it by shifting the production phase to avoid reinforcing the networks.

A renewable hydrogen highway

To put forward its arguments, Storengy is launching, over the 2021-2023 period, the Hypster demonstrator project, a storage of renewable hydrogen on its Etrez site, in Ain. It will enter the commercial phase in 2023. Hypster brings together 7 partners (industrialists, researchers, consultants in low-carbon solutions) and the 3 countries where Storengy is present. The investment budget reaches 13 M€ (5 M€ of European subsidies). This new industrial facility consists of a salt cavern with a capacity of 44 t associated with a 1 MW electrolyser.

At the same time, Storengy is leading the development of a European transport network dedicated to hydrogen. Currently essentially Franco-German, this "Backbone H2" is planned to transit from Marseille to Hamburg, via Cologne and Hanover. Thus, in France, underground cavities such as those of Manosque, Tersanne, Etrez or Cerville will only be dedicated to hydrogen, and the pipelines which initially transported natural gas will be converted to be able to transport this molecule. In addition, on this main trunk, new branches of pipelines will be built and connected to irrigate France, Germany and other Central European countries.

This project is part of the company's Vision LT of a "100% carbon-free gas" scenario. It confirms the paradigm shift of energy manufacturers regarding 100% renewable electricity and their battle order to bring it to an end.

^1- https://negawatt.org/Le-systeme-electrique-peut-il-fonctionner-avec-100-de-renouvelables-replay

^2- http://www.centre-cired.fr/fr/ International Center for Research on Environment and DevelopmentWebinar: Is 100% renewable electricity possible in France? by 2050 and, if so, at what cost? (http://www.centre-cired.fr/fr/webinaire-une-electricite-100-renouvelable-est-elle-possible-en-france-dici-a-2050-et-si-oui-a-quel -cout/)What optimal electricity mix in France in 2050 (http://www.centre-cired.fr/fr/quel-mix-electrique-optimal-en-france-en-2050/)

^3- Massive Integration of power electronics devices (https://www.h2020-migrate.eu/)

^4- RTE and the IEA publish their study on the conditions for an electricity system with a high share of renewable energies in France by 2050: https://www.rte -france.com/actualites/rte-aie-publient-etude-forte-part-energies-renouvelables-horizon-2050

^5- In France, a second player, Teréga, a subsidiary of Total, manages 2 sites.

About the author

Bernard Reinteau

A journalist in the building press since the end of the 1980s, Bernard Reinteau is a freelance journalist. He has worked for the Public Works and Building Monitor, the Heating Journal, and Chaud Froid Performance. He is particularly interested in technical construction solutions, the environment, renewable energies, the energy and environmental performance of buildings. He mainly collaborates with the biggest construction press titles and in particular with Xpair.