Good winds ahead
World Energy Focus talks to Michael Hannibal, chief executive of offshore operations Siemens Gamesa, the company's renewables division, about what has driven its development and how the industry plans to continue to drive down the cost of renewable energy
Offshore wind power has come a long way since the first turbines began operating at
Vindeby, Denmark, in 1991. That installation was recently decommissioned. With 11 turbines, each producing 450 kilowatts, it now seems a far cry from the large-scale turbines producing hundreds of megawatts at wind farms today.
But it is only in the last few years that the industry has seen an acceleration that has surprised even the most ardent wind power supporters. Not only has technology advanced but the wind sector has matured and industrialised to a level that has seen the levelised cost of energy (LCOE) reach its 2020 target level of €100/MWh ($113.50) three years ahead of schedule. And there is more to come.
According to Hannibal, the industry has got where it is today through continuous innovation.
"From the early days, we developed platforms and evolved them to produce more and more energy. Then there would be a revolutionary step to the next platform," he says. "For example, the 2 MW turbine became a machine with a larger rotor and a larger rating to 2.3 MW; then there was the jump to the 3.6, which evolved to 4 MW through a larger and larger rotor; and then there was the revolutionary step to the 6 MW, which today is the platform for the 6, 7 and 8 MW units."
At the same time, the industry has gone from placing a handful of single turbines on the water to installing entire wind farms, with the commissioning of
London Array in 2013 (including 175 turbines and 20 wind farms) marking the point where power plants were essentially being built at sea.
"London Array is so big that it can replace an entire onshore power plant," notes, Hannibal. "It has been a remarkable development. To come from small turbines to real power plants at sea has been an exciting journey to be on. It has happened over 20 years or so, with the real acceleration coming during the last 10 years."
Offshore wind power has developed quickly in terms of technology, scale and job creation while consistently beating cost reduction estimates.
Hannibal says: "We have constantly forecast to say where we will be in five years, 10 years, etc. And basically the 10-year point has been reached within five years by bringing in elements such as bigger turbines and industrialisation.
"The new wave is digitisation, where computing power is being used on our backlog of data. Basically, how you run a turbine or wind farm offshore has moved from reactive servicing to pro-active, and now with digitalisation, to interactive servicing. Here, we can look at a digital twin [model] of a turbine to model what will actually happen with the turbines."
All of these developments have seen offshore wind take a role in the generating mix that is indisputable. Wind provided more than half of all renewables growth in 2016, said BP in its
2017 annual statistical review. Yet challenges remain if this rollercoaster progress is to continue. Policy, technology and manufacturing are all key areas that could present obstacles.
Hannibal says policymakers need to continue their drive. "They could fall into the trap of, say, stopping subsidies or volume tomorrow because they have proven they are now where they should be.
"If we want to make the [cost] curve price points and the drivers for those points sustainable, there needs to be a pull from society. To run stable production factories, developers have to be sure that projects are coming," says Hannibal.
Manufacturers and developers essentially have to be sure that there are certain volumes in the market in order to make the investments needed that will keep bringing costs down.
Hannibal says that technology and manufacturing challenges go hand-in-hand. While the industry has been able to design larger and larger machines, he notes that the size-to-weight ratio is not linear. For example, if the weight of a hub for a 6 MW unit is 50 tonnes, it does not mean that a 12 MW turbine hub will weigh 100 tonnes.
"When the weight to power ratio is not linear, you start to go against the thinking that bigger is more beautiful. So technology and manufacturing have to work together to determine where the real optimum is for the next generation turbines."
This not only applies to turbines but to foundations, towers, vessels for installation, etc. While it may possible to engineer and even build a very large turbine and even install a single unit, commercialisation and industrial production may be too difficult, resulting in a high LCOE from the wind farm.
"This is the current challenge for the next technological step for offshore turbines," says Hannibal.
In addition to the ongoing innovation in turbines, the last four or five years has witnessed notable advances in foundations. Prior to this, foundations were typically built one at a time in a shipyard.
"We came up with several foundation designs with the aim of having one that could be serially produced. With our concept you can do a lot prefabrication so you can perform lean manufacturing and assembly of components," Hannibal explains."This has challenged some of the other foundation manufacturers, leading to more innovation in the area over the last couple of years."
He adds that because foundation manufacturers started later than the turbine manufacturers, there is still room for improvement in the area.
Driving down costs
Looking ahead, Hannibal anticipates several things coming together that will result in the LCOE from offshore falling to nearly half of what is today over the next decade or so.
For existing turbines, evolving technology will allow more energy to be produced from machines already installed. At the same time a new generation of larger machines will cut costs further. The electrical grid system will also be a key area that will contribute to lowering electricity costs. Just over a year ago,
Siemens introduced what it calls the Offshore Transformer Module (OTM). The much reduced size and weight of the lightweight AC grid access solution serves to lower capital spending by up to 40% and is expected to reduce wholesale energy costs by £1.7/MWh ($2.2) in 2015 prices. The first OTMs have now been sold and will be installed at projects in the UK and Germany.
In servicing, using data from machines in the field is also expected to drive down the cost of energy.
Hannibal says the project developers will play a major role in improving efficiency. "They now have a good understanding of risk and opportunities. This has a positive impact on the LCOE. Also we are currently supported by the low cost of capital."
All of these factors lead to a prediction of LCOE reaching below €80/MWh in 2025. And Hannibal believes that with a sustained volume of projects, this could fall to around €50- 65/MWh between 2025 and 2030.
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