Within the energy transition process currently taking place, renewable energies have been identified as one of the main drivers of transformation. For example, in February 2018, renewables (excluding hydraulic power) overtook coal for the first time in the European electricity mix. And by 2030 they are expected to account for 50% of this mix.
Wind turbines and fields or roofs decked with solar panels are now part and parcel of our everyday landscape. But behind these visible aspects of renewable energy sources lies a concentration of technologies and a race for innovation to improve their efficiency, maintain them and integrate them into power grids, while ensuring that they remain financially, ecologically and socially viable.
“Innovation is essential to accompany the sector’s transformation and meet the challenges of the future”, says EDF Énergies Nouvelles, the renewable energies arm of the French utility company, EDF. “We are working with EDF’s R&D teams which carry out technical research and tests on projects aimed at providing solutions to the problems of incorporating renewable energies and managing their intermittent production. We are already working on new business models (decentralised production, energy storage, contracts with major corporations for them to sell electricity back to the grid, etc.).
Capturing ever more solar power
In this context of intense engineering needs, solar power technologies are still a particularly popular area of innovation. The reason is simple: the Earth receives more energy in one day from the sun than it uses in one year. The potential is therefore enormous – we just have to leverage it!
The efficiency of crystalline silicon solar cells and cadmium telluride (CdTe) wafers has grown in the space of the last ten years and has now reached 20%, enabling solar panels to be manufactured on a mass scale.
However, current research and innovations promise even better efficiency. One of the greatest hopes today is the use of solar cells made of perovskite – a highly polyvalent and inexpensive material. During laboratory testing, these cells have already attained an efficiency of 22% in less than 5 years of tests. A success that led Michael Saliba (ranked in 2017 by the MIT Technology Review as one of the top 35 innovators aged under 35) to state that they are “the future” of photovoltaics.
As we wait for the chemical processes underway to stabilise and for the ensuing technology to be industrialised, it is clear that numerous developments are in the offing for the surface area that can be used to capture the sun’s rays and heat.
Working in partnership with the CEA and the Institut National de l’ Énergie Solaire, the engineers of the Armor group based in Nantes, France, have created a solar film called Asca which is a malleable and organic solar power support made from polymers. Containing no silicon or precious metals, thanks to its malleability, this technology can be incorporated into small objects such as bags, clothes or sun awnings as well as any other surface exposed to the sun, even if it is curved. Although the expected efficiency is only 8% (4% today), the advantage of this innovation is that it can maximise solar coverage, from bus shelters to swimming pool covers.
With the same aim of capturing ever more solar energy, engineers from the LafargeHolcim group and the start-up, Heliatek, have recently invented a prototype of a photovoltaic building facade which combines fibre-reinforced concrete panels with an integrated power production system. Meanwhile, Sunpartner has gone one step further by launching, on 5 October 2017, its first production line of transparent and coloured solar panels that invisibly clad the facades of buildings.
In the solar power market for private individuals, the technology developed by manufacturer Systovi avec R-Volt is of particular interest. Called Aérovoltaïque, this solution allows the production of electricity and heat and enables residents to use up to 80% of the solar energy captured on their roof during the day. “The front side of the panels produces electricity and on the reverse side hot air is collected via a patented air duct. This air is then sucked in and filtered through a thermostat-controlled central air processing and energy management system and is blown into the dwelling as required”, describes Systovi.
In order to improve efficiency, an increasing amount of technology is being integrated into solar power systems. “We’ve identified two new technologies that can help improve the efficiency and production of a solar power unit: trackers (which can increase a panel’s efficiency by up to 30% by following the course of the sun )and two-sided modules”, explains EDF Énergies Nouvelles. “These modules produce energy via both the front and the back. The efficiency gain achieved through the energy generated on the back of the module via reverberation can reach 50% for surfaces with high reverberation levels, such as snow. For ordinary surfaces the gain is around 10%.”
The huge potential of offshore wind farms
Wind power is another source of renewable energy that is attracting not only engineering talent but also investments from both major groups and start-ups in order to tap its full potential. While onshore wind farms are evolving in terms of power and robustness, it is offshore farms – both on and in the water – that are drawing the most attention. There are already more than 3,500 wind turbines off the European coast, representing 12.6 gigawatts of power, and floating, tidal and wave technologies are paving the way for huge opportunities to generate energy from the planet’s seas and oceans.
According to EDF Énergies Nouvelles, “For several years now, our company has positioned itself as a specialist in the emerging technology of renewable marine energy – in tidal energy, with a tidal farm currently under construction at Raz-Blanchard in the English Channel, and in floating wind farms, with a pilot project in research phase for off the coast of Fos-sur-Mer in the south of France.”
Called Provence Grand Large, this latter project comprises three 8 MW turbines supplied by Siemens Gamesa and a floater system developed by SBM Offshore and IFP Énergies Nouvelles, all installed 17 km off the coast of Port-Saint-Louis-du-Rhône.
Another French pilot project is Floatgen, which is being tested off the west coast from the town of Le Croisic. Fitted with an innovative concrete floater anchored to the ground by nylon cables, this floating wind turbine – developed by the start-up Ideol in association with Bouygues TP and the École Centrale de Nantes – should soon be supplying power to 5,000 homes.
It’s not just in France that floaters have become all the rage. Scotland has recently gone beyond the prototype stage by being the first in the world to connect up a floating wind farm to the electricity grid. Called Hywind and comprising 5 floating turbines located 25 km offshore, this wind farm was developed by the Norwegian company Statoil and UAE-based Masdar. Standing 253 metres high, each turbine is mounted on a 90m-long semi-submerged floater filled with 5,000 tonnes of iron ore. It’s a real engineering feat and Statoil and Masdar say the turbines can operate in water depths of up to 800m.
Operating offshore is the whole advantage of floating wind farms. Not only do they appease the critics for whom onshore turbines are a blot on the landscape, but they also generate more energy, as winds are stronger and steadier offshore.
Researchers are also actively pursuing their studies of tidal technologies, which harness the power of ocean currents. Sabella in France was one of the first companies to install a tidal power station (off Ouessant Island in north west France), which now supplies electricity to the whole island. And EDF Énergies Nouvelles has begun work on a pilot tidal farm – Normandie Hydro – in Raz-Blanchard. “Our objective is to demonstrate the viability of the technology, operating model and maintenance solutions for tidal farms in order to create them on an industrial scale. And we want to test the amount of output from a tidal farm that has some of the strongest undersea currents in the world”, says EDF Énergies Nouvelles.
Still in France, but further north, at Boulogne-sur-Mer, Eel Energy is testing a brand new technology: a tidal turbine with an undulating membrane developed under the leadership of Eel Energy’s President – Jean-Baptiste Drevet – an engineer who has worked on fluid-structure interactions for the past twenty years. It uses a membrane shaped like a large flipper, which undulates like a fish against tidal currents of 3m/second, causing it to produce electricity. Although still in its early stages this innovation illustrates the advantages of tidal power, of which France has the second-largest potential in Europe.
Another technology with huge prospects is wave power although this is even more in its infancy than tidal power. Like the current, waves form regularly day and night and are a lot stronger than tidal movements. Two industrial players have particularly invested in developing an efficient, manufacturable and financially viable engineering solution for harnessing wave power – the Finnish company Fortum and the Dutch firm SBM Offshore.
Energy storage: the most closely scrutinised area of innovation
If there is one area of research and innovation where engineers are being asked to demonstrate their skills, it’s energy storage. Because in order to achieve a future energy mix composed entirely of renewables, we have to prevent wasting surplus energy produced on sunny days for solar power and in windy weather for wind power. Linked up to city grids (both smart and non-smart), energy storage systems enable the stored energy to be used later and therefore smooth demand.
That is why the potential of batteries is being widely researched and tested. “EDF Énergies Nouvelles is working on two storage projects: the Toucan solar power station in French Guiana (5 MWc) and the McHenry project in the United States (20 MW in nameplate capacity and 40 MW of flexible capacity), says EDF Énergies Nouvelles. “These two projects have an innovative storage system that combines a power storage battery and an energy management software”.
EDF Énergies Nouvelles’ UK subsidiary is working on a project it was awarded to provide 49 MW of battery storage at the West Burton combined cycle gas power station in Nottinghamshire. “Against a backdrop of strong growth in renewable energy production and the closure of large power plants, battery-storage technology helps smooth the output of the national electricity grid. The storage system can be activated on the grid to respond quickly to fluctuations in demand”, explains EDF EN.
As well as batteries, other technologies currently being researched or rolled out are based on the power to gas concept – i.e. converting electricity to gas, such as hydrogen, which once compressed can be more easily stored. It would be impossible to list here all of the hydrogen storage projects in process, but French precursors in this domain were the Corsican project Myrte and the company, McPhy Energy, and a recent example is the Smart Energy Hub launched by the start-up Sylfen.
The Smart Energy Hub was born out of ten years of research work conducted within the CEA, enabling surplus electricity to be stored in the form of hydrogen and then given back to users when needed. Covered by 22 patents, this solution stands out because its energy processor is reversible. “It’s a worldwide first”, according to Nicolas Bardi, President of Sylfen. “Our equipment can operate like an electrolyser to transform into hydrogen the surplus electricity produced locally and, inversely, like a fuel cell to turn the hydrogen back into electricity when required”, Bardi told Le Monde newspaper in April 2017.
Renewable energies therefore lie at the heart of tomorrow’s engineering landscape. But to be rolled out widely and sustainably they need a broad array of skills in areas such as electrical systems, digital technology and resistance of materials.