Op-ed articles

Power grids: discover the op-ed of two experts

Michel Derdevet
Michel DerdevetSecretary General and Member of the Board of Enedis

"We need to broaden the discussion to the challenges of distribution, which covers all local low and medium voltage networks."

Power Grids as Vectors of Solidarity

Political debates on energy in France as well as in Europe are often restricted to unproductive cultural clashes around generation methods, pitting supporters of renewable energies and nuclear powerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output... against each other. People tend to forget about the power grids that connect regions and people beyond their borders, tie in renewable energies and constitute a platform on which, tomorrow, the energy transition and the digital revolution will converge. Michel Derdevet, a renowned expert in European power grids, argues the case in this article.

The classic image of a power grid is that of huge, extra-high voltage (EHV) power transmission infrastructure, with giant pylons straddling fields and mountains. We need to broaden the discussion to the challenges of distribution, which covers all local low and medium voltage networks. Up until recently, distribution networks served people vertically, feeding out of the EHV network. Now, they have also become extensive collection networks, hosting the majority of wind and solar power produced by hundreds of thousands of scattered facilities.

At the same time, these distribution networks make it possible to more effectively take account of demand to assist consumers in their efforts to improve efficiency and reduce energy use, while providing them with an increasing quantity of easy-to-understand smart data. With the arrival of smart meters, such as Linky in France, power grids will have to manage a considerable amount of data. This data must first be put back into the hands of consumers and all local and regional decision-makers, who are eager to play a part in the energy transition.

In this way, power grids are more than simply technical or economic feats, they form part of a vision of society that dates back well into the past. In the early 19th century, the Saint‑Simonian movement encouraged industrialists, engineers, scientists and individuals to come together and build a more fraternal, economically efficient society than that found under the worn concept of autarky, where each region lives off its own resources.

Power grids therefore become vectors of solidarity, helping people to avoid withdrawing into themselves and share resources beyond their own community, with all the diversity and synergies that has to offer. This quest inspired the idea for the European Energy Union.

Equality Among All Consumers

Directly after WWII, France organized power distribution into a public service, a novel and unique approach in Europe which has since far beyond proved its worth.

The low and medium voltage networks belong to local or regional authorities which, generally speaking, delegate network operation to the national utility – EDF until 2007, then ERDF, which has since been renamed Enedis – to ensure regional cohesion and equal treatment for all consumers.

This organization has helped to incorporate the concept of solidarity into power generation and optimize costs, with distribution tariffs currently among the lowest in Europe (23% lower than in Germany). To date, it has ensured equal and consistent treatment across the country, in both urban and rural areas, thereby avoiding an electricityForm of energy resulting from the movement of charged particles (electrons) through a conductor... "divide" between the haves and have-nots.

At a time of increasing regional polarization, as confirmed by geographers, and the emergence of major urban hubs, ties with peripheral communities are clearly cemented by networks, whose financial and operational set-up must continue to be based on solidarity.

In Europe, these networks also have the potential to play a vital role in industry, particularly in terms of pooling investment and increasing cooperation in research. To stay competitive, especially with China and the U.S., we urgently need to prioritize and unify R&D across Europe to focus on a few major areas, such as energy storage, clean mobility, smart grids and direct current. A genuine industry policy on energy infrastructure is possible, so let's champion the idea with determination and ambition!



Michel Derdevet is Secretary General and Member of the Board of Enedis, and senior lecturer at the Paris Institute of Political Studies (IEP) and at the College of Europe in Bruges. From 1997 to 1998, he served as Chief of Staff for Christian Pierret, Minister for Industry, then member of the executive committee for French transmission system operator RTE between 2000 and 2012. He is the author of a number of works and has recently published Énergie, pour des réseaux électriques solidaires (with Alain Beltran and Fabien Roques, May 2017, Editions Descartes & Cie). He also drafted the report "Energy, a Networked Europe" at the request of the French president in February 2015. 


Valerick Cassagne
Valérick CassagneHead of the TotalEnergies Company's photovoltaic development operations

"The district, and the interconnected buildings located within its boundaries, have the ability to independently produce photovoltaic power and store energy, heat and cold."

IssyGrid, a Smart Grid to Improve Energy Management

The Paris suburb of Issy-les-Moulineaux launched a project in 2013 to study the development of a "smart" district. A life-size test lab, IssyGrid monitors the energy consumption and production of around 2,000 residents and 5,000 employees over an area spanning 100,000 square meters. Valérick Cassagne, a representative of the Total Group, took part in the project1 and explains a few of its main characteristics in this article.

IssyGrid is the first district smart grid in France, putting energy management to the test on a variety of different scales: within a building, across the neighborhood and throughout the city of tomorrow. The aim is to enable residents, companies, stores and offices to optimize energy consumption within their district in order to reduce both energy bills and greenhouse gas (ghg) Gas with physical properties that cause the Earth's atmosphere to warm up. There are a number of naturally occurring greenhouse gases... emissions.

The district, and the interconnected buildings located within its boundaries, have the ability to independently produce photovoltaic powerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output... and store energy, heatIn the field of statistical thermodynamics today, heat refers to the transfer of the thermal agitation of the particles making up matter... and cold. At the same time, they are connected to the public power grid. In developed countries, power grids are highly reliable but they have been designed to supply power to meet annual peak demand levels. The rest of the time, they are underused.

In a "smart" district, a two-way data distribution network is connected to the public power distribution network. At any time, producers and distributors know how much energy consumers are using, and consumers can see the extent of grid congestion in real time. All parties are able to access the necessary information to make the best choice, individually or collectively. Decisions can be made at either the building or district level in order to achieve maximum efficiency, both in terms of cost and environmental impactAny change to the environment, whether adverse or beneficial, wholly or partially resulting from human activity... .

IssyGrid uses photovoltaic solar technology to produce electricityForm of energy resulting from the movement of charged particles (electrons) through a conductor... for the district. Energy is stored in either stationary batteries installed in the buildings or mobile alternatives fitted in electric vehicles. Storing energy can still be extremely problematic, in terms of cost rather than technology: batteries are expensive, and it takes a long time for the savings they generate to cover the cost of their purchase. Currently, they do not therefore present any economic benefit over the power grid. But every year the cost of this equipment is falling by 10% to 15% and, in countries where electricity is expensive, like Germany for example, the solar power/battery combination is becoming increasingly competitive.

Two tangible innovations developed during the IssyGrid project were:

  • Weather forecasting – To better manage and make use of solar power, it is essential to be able to anticipate the amount of sunlight that panels will receive. Traditional weather forecasts are reliable up to around a day or half a day in advance. We developed systems for very short-term forecasting (from several minutes to an hour), whereby 360 degree images of the sky are taken in real time using an infrared camera. These images are sent to a company located thousands of miles away on Reunion Island, which process them to predict cloud movements and therefore the amount of sunlight. We then use this data to calculate how much power will be generated in the following minutes. This enables us to decide whether to store the energy or align our consumption with the peaks and troughs of this form of power generation.
  • Staggered consumption – We conducted an experiment in the tallest office block in the district. In the height of summer, we turned up the air conditioning for two hours in the morning and then turned it down for an hour and a half during the afternoon when overall consumption was at its peak. By staggering power use in this way, we were able to reduce total district consumption by 350 kilowatts. The temperature in the offices increased by just 0.2 degrees Celsius, so the people working there could not feel any difference.



An engineering graduate from Arts et Métiers in Paris and Ph.D. in materials science, Valérick Cassagne has managed the Total Group's photovoltaic development operations since 2009. He was previously Director of Research and Development at Unaxis and Riber before becoming Head of Mechanical Metrology at the French National Laboratory of Metrology and Testing (LNE).


Source :

(1) See the IssyGrid website – In addition to Total, partners include Bouygues (Immobilier, Energies & Services, Telecom), EDF, Enedis, General Electric, Microsoft, Schneider Electric and Sopra-Steria. 

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