26km off the windy coast of northern Scotland, the future of renewable energy is taking shape. Swinging in rhythm with the wind, the five giant turbines at the Highwind Scotland wind farm look like any other offshore wind project, with one difference: they float.
Whereas traditional offshore wind turbines are mounted on metal and concrete towers attached to the sea floor, highwind wind turbines are supported by floating steel keels that flow with the waves. Carefully balanced, they stay upright despite the waves of the ocean. This seemingly simple, yet devilishly complex design is changing the way green developers view offshore wind power.
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This could be a significant development as the world strives to meet the net zero carbon target of countries committed to the Paris climate change agreement. The energy sector as a whole currently accounts for about three quarters of the greenhouse gases emitted by human activity.
According to the International Energy Agency, reducing these emissions will require green electricity to be at the heart of global energy. It states that by 2040, half of the world’s energy needs will have to be met with net-zero generated electricity.
With the increasing number of electric vehicles and the increasing demand for electricity to replace fossil fuels in domestic and industrial uses, the power grid will also need to become more resilient and offer more ways of producing and storing energy. This means that by 2045 our energy grid could be radically different than it is today.
Projects like the Highwind Floating Wind Farm offer a present-day glimpse into the future.
There are two reasons for this. First, unlike stationary units, floating turbines can operate in deeper waters away from shore, where winds are faster and more regular. The world’s most densely populated coastal areas lie along these deep waters, according to Danish inventor Henrik Steisdal at the forefront of floating wind innovation. According to him, this gives floating air another advantage: it can serve communities that do not currently have significant wind power potential.
“Many countries have large offshore areas close to their population centers, but at depths that are great for turbines attached to the bottom,” Steisdall says.
“In places like Korea, Taiwan, Japan, and California, you can only manage a moderate amount of conventional offshore wind turbines, if any, with floating turbines being the only long-term option.”
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While floating turbines can overcome some of the problems that make offshore wind farms in deep water impossible, there are still challenges ahead. Some are concerned about the impact that large arrays of floating wind turbines can have on the marine environment.
The cost of floating wind turbine projects is still higher: it costs almost twice as much per megawatt hour of electricity produced than stationary offshore wind turbines. But these costs are expected to come down as technology takes hold, as has been the case with other wind power projects.
But when one question is answered – how to cut winds in deep and distant waters – another arises: what to do with the electricity produced?
Grid constraints have long been a problem for wind power developers, fearing system overloading when it comes to systems, especially in windy conditions. To avoid this, turbines are regularly de-energized, a costly process known as power reduction. And what happens when the wind isn’t blowing hard enough? If we add to the logistical challenge of laying tens of kilometers of submarine cable, it is clear that another approach is necessary.
Although high voltage submersible power cables are now relatively common, they are expensive to install and maintain – five to ten times more than overhead lines by some estimates.
This is where hydrogen comes in, the most abundant element in the universe and, for many, the key to the future of floating wind power.
“If it’s particularly windy outside and you have excess electricity being generated, one option is to shut down the system,” says Scott Hamilton, head of the renewable energy division at Xodus, an energy company. Energy Consulting. “Instead of wasting those extra electrons, we can use them to make hydrogen.”
To do this, you need an electrolyzer – a machine that separates water into its components: oxygen and hydrogen. When renewable sources are used to power this process, it is referred to as “green hydrogen”.
Highly combustible, hydrogen can replace fossil fuels as a carbon-free energy source. On the Scottish island of Orkney, a world leader in green hydrogen development, the gas is already being used to power vehicles and heat buildings, and a hydrogen ferry is expected in the not-too-distant future. A similar pilot project, also set to be completed in 2023 in Buckhaven, Fife, Scotland, will use renewable wind power to produce hydrogen for heating and cooking around 300 homes.
The fact is that hydrogen can be stored – compressed and pumped into tanks – and transported like gasoline or diesel. This is why the developers of floating wind turbines are so concerned.
Attached to the floating base of a wind turbine, an electrolyzer can instantly harness wind-generated electricity to produce green hydrogen from desalinated seawater. With the strongest winds accelerating hydrogen production, grid problems and shortfall calculations will not hinder the process.
Several companies in the energy sector are interested in this technology, and one of the developers, ERM, expects a prototype to be operational by mid-2020.
Once the prototype is operational, the green hydrogen generated from floating air has immense potential for use. As a fuel for vehicles, analysts such as Jess Ralston of the Energy and Climate Intelligence Unit say it lends itself to heavy and long-distance transport – road, rail, sea and even possibly air. gives. Thus hydrogen could fill the gap in electricity generation by the middle of the century.
“It’s not too hard to imagine a situation where a country with a large floating air capacity sells green hydrogen abroad, shipping it in giant tanker-type vessels or through pipelines”, says head of hydrogen development at European James Walker explains. Marine Energy Center. “We may also have a situation where electrolyser-equipped floating wind turbines serve as refueling stations for long-distance ships.”
It’s an exciting sight, but the adoption of green hydrogen faces its own obstacles. Its production is currently expensive, but the International Energy Agency estimates that as renewable energy becomes cheaper to produce, so will green hydrogen. There are also concerns about the safety of storing large amounts of hydrogen, and development of the infrastructure needed to transition to a hydrogen economy has been slow.
This means that in order to meet the ambitious net zero emissions targets, all kinds of sustainable progress will need to be made. Massive production of solar energy, new ways of harnessing marine and geothermal energy, as well as breakthroughs in biofuel and battery technologies will all play a part.
But with these bottom-up eco-innovations, floating wind power and green hydrogen will find their place, helping to pave the way for a future powered by net zero emissions and carbon-free fuels.
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