Low-carbon electricity generation is critical to Europe meeting its emissions targets. Making sustainable energy production as efficient and cost-effective as possible is a key part of this challenge. “A good example is offshore windfarms, where energy has to be transported to the mainland via underwater cables,” says GreenDiamond project coordinator Etienne Gheeraert from the University of Grenoble Alpes, France. To transport this electricity, two high-voltage converters are used – one at the wind farm, and another on the mainland. These converters usually contain silicon power devices. “This is a weak point,” explains Gheeraert. “Silicon is cheap, but a poor material for conducting high-voltage electricity.” The choice leads to high losses during energy transfer.
Industrial diamond power
The EU-funded GreenDiamond project, which was coordinated by the French National Centre for Scientific Research (CNRS), sought to meet industry demand for alternative semiconductors. The focus of this research was on a mineral with a reputation for luxury and decadence – diamond. “An important message here is that producing diamonds is not expensive!” notes Gheeraert. “It is actually quite easy to fabricate from methane and hydrogen or graphite.” This process gives a crystalline quality that is much better than natural diamond. “Diamond is the ultimate semiconductor,” adds Gheeraert. “No semiconductor has better intrinsic properties. We are still in the silicon age, but we are about to enter the carbon age with graphene, nanotubes and diamond.” The price of industrial diamonds is currently linked to the gem market, where the prices are significantly marked up. Gheeraert is confident that the two markets – industrial and gem – will soon split, with an emerging technology market offering synthetic diamond at a low cost. “The first challenge we faced was fabricating a new converter with diamond power devices inside,” says Gheeraert. “This required the development of semiconductor technology for diamond, based on standard silicon technology.” The project team also developed a device package to manage high power and high temperatures of up to 250 °C. “We wanted to make sure that our converter was as reliable as a regular converter,” explains Gheeraert. “This is critical. No maintenance should be required for offshore power converters.”
Capturing the market
Significant progress has been made on several of the key technologies. These include the design of the diamond devices, the high-temperature, high-power package and the diamond converter. Initial assessments suggest that the diamond power devices are four times more efficient than traditional silicon converters, resulting in a potential 75 % reduction in electricity losses. “Ultimately, all high-power electrical systems can save energy by using diamond devices,” he observes. Applications could include long-distance power lines, airplanes and industrial converters. Hydrogen production could be another viable end user, as this requires a huge amount of electrical power. The goal now is to attract more interest from industrial partners. Diamond is still associated with luxury goods and high prices. Effective communication is needed to promote the potential of low-cost industrial diamond production. Gheeraert and his team can then start moving towards commercialisation. Project partners have already created two start-ups dedicated to diamond electronics. The continued strong involvement of industrial partners in the development of this technology, adds Gheeraert, has been one of the key achievements of the project. Gheeraert is confident that diamond electronic technology will dominate the market. “It is critical that we keep this research going in Europe,” he says. “Otherwise the diamond energy conversion market will be dominated by others.”
GreenDiamond, energy, diamond, semiconductor, sustainable, windfarms, electronic, carbon