Politique Internationale — The solar road is something we keep hearing about, but very few people know exactly what it is. Can you tell us a little bit about its history?
Anis Jouini — It all started with a global reflection process on how to make better use of existing artificial surfaces and make them more functional. All surfaces: not just roads but also cycle paths, roofs, gardens, swimming pool decks, terraced areas, etc. All these surfaces are exposed to the sun, with the often far from insignificant potential to produce photovoltaic energy. These sites are not necessarily stationary or permanent. They can offer additional services. Take the roof of a truck, for example, and bear in mind that truck drivers, who spend hours at a time in their cabs, need electricity for a TV, a microwave and heating; a 2 kilowatt (KW) installation on the roof will provide all the energy they require for their day-to-day needs. To go back to this problem of surfaces, we’re now shifting from a single functionality to several: a road that was previously only used for vehicles to drive on, or a roof designed for the sole purposes of protecting a home will now be able to offer a broader range of services.
P. I. — How does the technology work? Is there a set, standard blueprint for the function of a solar road?
A. J. — The identification of the site, such as the ones I’ve just mentioned, plays an important role; preferably an area with significant exposure to sunlight. Then it’s a matter of targeting a use, or an application. It depends on whether we’re talking about an isolated section of a parking lot, a cycle path, a main road or a very busy highway. With a road, for example, we could easily incorporate solar panels to produce energy, and then build an electricity storage station alongside this road, to power nearby facilities, such as e-bike charging stations, lighting, toll booths, a service station or business premises. In many cases, this type of solution proves to be much cheaper than connecting the facilities I’ve just mentioned to the main power grid, since that would require trenches to be dug to bury the cables. On a busy road, one option would be to use the solar energy to power adjacent traffic lights, for example. The solar road is not immutable technology that we simply replicate without question: the quality of the location and its energy reserve will govern how much power is produced. It should be pointed out that building a solar road is not the same as simply installing solar panels: a solar road is an infrastructure that, in some instances, needs to be capable of carrying thousands of vehicles per day. In concrete terms, solar cells, of standard design, are bonded together using a glass aggregate resin. The resulting slab is stuck to the asphalt mix to form a highly resistant material. Projects such as these are carried out by construction industry professionals who are perfectly skilled in the techniques involved.
P. I. — Is the solar road still at the prototype stage or has the technology already been deployed on an industrial scale?
A. J. — Several prototypes are already in operation. We’ve built more than 40 demonstrators, of various designs and sizes, that have been tested at several locations. For example, a busy junction in Nantes, a cycle path in Montpellier and in the grounds of the Technolac technology park in Chambéry, where CEA-INES is based. These first trials have now paved the way for the transition to the next phase: currently in France, the solar road is being tested at around forty pilot sites. So we have sufficient feedback to begin the industrial phase. The fact that the innovation has attracted significant interest from outside France backs this up: partnerships have been forged with Germany and Japan to develop the solar road.
P. I. — Who is in pole position where the solar road is concerned? Construction sector operators, infrastructure groups, energy providers, engineering specialists, etc.?
A. J. — One thing is sure, it is difficult to go it alone. In actual fact, we’ve formed a three-way partnership involving CEA-INES, Colas and a solar module manufacturer, VMH, based in the Vienne region of west central France. The pooled specialist expertise and experience of the three partners reflect the scale of the challenges associated with the solar road. All the work we’ve accomplished together has been properly patented. While we are not alone in the solar road sector, we are, without a doubt, pioneers in the field. Projects seeking to challenge us - and there are some, as is traditional in the wake of a technological development - will not be capable of catching up with us overnight: when it comes to research, there are preliminary steps that everyone has to go through. By the way, our research in this field is not subsidized: the public authorities are watching our initiative closely and have helped us by hosting and supporting trial sites.
P. I. — How far do you see the development of the solar road going? Do you believe it will become standard equipment one day?
A. J. — Projections are all the more exciting because they are supported by the rapid development of electric cars. The entire planet is heading towards the mass electrification of its needs in general, but that is especially true where mobility is concerned. The day will come when these vehicles represent the dominant sector and charging stations will be needed at regular intervals: in service stations, rest areas, highway exits, etc. A dense solar road network will be an ideal option to power these charging stations. We are currently also looking at the possibility of solar walls running alongside some of the busiest roads: for the time being, walls of this type are designed only to reduce noise but, once again, it would be possible to incorporate another functionality. The solar road is a foundation that offers opportunities for the development of other types of infrastructure.
P. I. — Have the benefits of the solar road in terms of global warming already been calculated? Do models exist that can be used to quantify the volumes of CO2 avoided as a function of the number of kilometers equipped?
A. J. — We are working on these questions but we don’t yet have access to models providing easy answers. Where the solar road is concerned, it is necessary to compare complete and complex systems for a specific location; each application scenario is different. The solar road replaces other ways of providing electricity at sites equipped with the technology. So, for example, we need to be able to compare providing access to the power grid and the work and equipment that entails with the equivalent requirements associated with building a solar road. Then we have to take into account the level of carbon in the energy mix at the location concerned, the amount of sunshine in the region, at the chosen site, etc. It is by taking into account all these criteria that we will be able to evaluate the volumes of CO2 avoided, or other environmental benefits for a given case. The carbon footprint of a solar road panel is better than that of a standard photovoltaic panel for the simple reason that it does not require an aluminum frame to maintain its structure.
P. I. — While solar energy, like wind energy, is developing at a rapid pace, opposition to renewable energies remains strong. They are often criticized for being heavily subsidized, damaging the landscape and not producing enough to justify the amount of investment ploughed into them. What is your view?
A. J. — Know this: photovoltaic energy around the world has just reached a new milestone, with a total installed capacity of one terawatt (TW). That’s more than one million megawatts (MW). Do you think that the industry would have followed this exponential trajectory if its competitiveness hadn’t been demonstrated, as well as being a clean energy set to play a leading role in tackling global warming? Its efficiency is also obvious; while it’s true that solar energy is intermittent in nature we’re able to predict this intermittence and thus match it with electricity needs. Unfounded accusations are levelled against the solar power industry: it is accused of seeking to establish itself as the only remedy for the future, whereas exactly the opposite is true. At CEA-INES, we are the first to defend a balanced energy mix, i.e., the possibility for countries to draw on several complementary sources of energy. France is a good example, with its dual objective of renewing its nuclear facilities while at the same time developing its renewable sector. Other countries favor a combination of gas and green energies.
P. I. — Will we go beyond this installed terawatt?
A. J. — I’m always saying that nobody can stop the sun. Yes, roadmaps and national energy planning programs call for several Terawatts of production internationally. Photovoltaic energy can be used to meet the energy needs of a small village just as it can an industrial site, with the huge advantage of relocating the means of production locally. Transport is the enemy of electricity: when transported over long distances, energy losses are considerable.
P. I. — As far as you’re concerned, the competitiveness of solar energy cannot be doubted…
A. J. — It is constantly improving as it becomes more mass produced, with the resulting economies of scale, bearing in mind that the two materials making up photovoltaic energy technology – glass and silicon – are not rare commodities. On a global level, solar energy is now the cheapest energy and it is also the most installed energy in recent years; here, I’m talking about conventional solutions of course. Its many benefits explain this: the technology is tried and tested, and reliable; it is quick and easy to install, with no risk of irreversible damage to the environment. We are getting better and better at storing solar energy and we are capable of managing it.
Its price varies depending on the country and the type and size of facility. Large-capacity, ground-based solar facilities produce electricity at a different cost compared to solar panels located on your roof or at a remote site. In the most favorable scenarios, where very large plants are operating in countries with long hours of sunshine, the price of electricity produced using photovoltaic technology can be as low as under two cents (€0.02) per kWh.
P. I. — Geopolitical crises pose a regular threat to the supply of materials. Not to mention the shortage of some equipment, such as semiconductors. Is the solar energy sector impacted by these events?
A. J. — It is a commonly held belief that for reasons of competitiveness, solar panels can only come from China. On the contrary, I am among those who believe we can and must construct an industry, a complete industrial sector in Europe, and hence, in France. We must do it for reasons of environmental, social and economic responsibility, as well as for our energy independence. In any case, crises of all types – health, economic, geopolitical – should encourage us towards sovereignty of supply sectors. Europe, France and all countries across the planet are now looking at things in a different light.
P. I. — Personally speaking, what was it that brought you to the solar road?
A. J. — I studied science before going into research, beginning my career at a research center in Japan and then moving to a start-up in the USA. I have been managing the solar energy technology teams at CEA-INES since 2013. And it was at the same time that I first encountered the solar road and the Colas team: I am passionate about this adventure, in terms of both its technological challenges and the potential for new innovations it provides for roads and urban development. And this flagship project is a unique opportunity, as well as a human adventure with a tight-knit team.