Smarter calculations can cut offshore wind costs further
Green transition 15 May 2018 Søren Juel Petersen Ronnie Refstrup Pedersen
To optimise the design of wind foundations and turbines, engineers need a platform for fast, robust and cloud-based data storage and execution. Ramboll has teamed up with Google Cloud to improve its in-house wind software in this area.
In March 2018 the Dutch government decided to develop the twin Hollandse Kust Zuid offshore wind farms – the world’s first to be built without a public subsidy. This represents a key development in the steep decline of renewable energy prices, and thus a major step in making wind energy increasingly competitive with fossil fuel.
However, there is still no guarantee that offshore wind will be preferred over fossil fuels, especially not in the developing world. Thus, the industry must continue to focus on cost-cutting measures, say energy experts like Luisina Berberian, Associate Director at Standard & Poor. In a blog at WindPower Engineering she writes that “ technological developments have contributed most to cutting costs and the subsequent boom of offshore wind projects”. At the same time, she emphasises that “hurdles, like a complex design process” remain.
An innovative way to tackle some of these challenges and further cut costs can be found, for example, in Ramboll’s software program Ramboll Offshore Structural Analysis Package (ROSAP). The calculations that ROSAP performs are so accurate and advanced that the steel required for an offshore Chinese wind farm could be reduced by 20%, thus enabling Ramboll to beat a local competitor’s bid.
Ramboll will now further improve ROSAP by utilising measurement data from the offshore wind industry. To this end, we will team up with Google and the IT specialists at Computas, a Norwegian IT solutions company able to provide the necessary advanced technologies that are both scalable and extendable. Google Cloud will supply the required advanced analytics packages, also both scalable and extendable, and Ramboll is enrolled in the Google Partner Program and participating in Google’s training courses on cloud architecture and data analytics – the aim being to establish a robust and fast cloud-based data storage and ROSAP execution platform.
First foreign advisor in China
ROSAP was originally developed by Ramboll's oil and gas division back in the 1980s. Around 2000, Ramboll added a small version for offshore wind turbines, which has now grown big enough to enable bids that are more competitive than those of state-supported Chinese companies.
Ramboll has a market share of around 60% of offshore wind foundations installed worldwide – all of which have a bearing capacity capable of supporting turbines even in weak and earthquake-prone seabed soils.
In 2015, the company became the first foreign advisor to design one of China’s largest offshore parks – SPIC Binhai North H1 in Jiangsu province, five hours’ north of Shanghai – and since then three other design orders have come from China, as well as two orders for design from Taiwan and one for project development in Japan.
"The secret here is that ROSAP can optimise the design of the wind turbine foundations", says Søren Juel Petersen, Wind Market Director at Ramboll.
No over-sized buffer
Competitors in Asia and elsewhere typically purchase software externally to calculate the impact of all relevant factors on wind turbine performance and stability. With ROSAP, Ramboll has all the answers in-house: How do waves, currents and tides impact the foundations – both in the general short term and in relation to long-term corrosion protection? What about the weight of – and loads from the wind turbine itself? And what kind of seabed are we talking about here? How does it react, for example, to soil liquefaction – a phenomenon where soil loses significant strength and stiffness in response to an earthquake or other applied stress, thus causing it to behave like a liquid?
Ramboll typically calculates more than 10,000 different combinations of loads from the above factors – referred to as load cases per wind turbine position.
"When there are, for example, 100 turbines in a farm, we typically go with three design positions, so we end up with more than 30,000 load simulations. On this basis, we can with great certainty determine how strong the various elements of the wind turbine foundation should be, among other things. And with the new cloud-based ROSAP execution platform, the large number of load calculations and associated data processing can be easily handled", says Søren Juel Petersen.
He stresses that without a software program like ROSAP calculations will often be over-conservative.
"You have to put in a buffer, and as you have to be cautious, you typically put in too large a buffer, thus investing too much. We can avoid this because our calculations are so accurate", he explains.
Mr Zhang Yi, a project manager with the Chinese State Power Investment Cooperation, has confirmed that the total price was a decisive factor in awarding the SPIC Binhai North H2 contract:
“Ramboll could supply a solution that was 20% cheaper than what the competitors had to offer and could deliver a better thought-out solution owing to its wide palette of competencies," says Zhang Yi.
Further optimising designs
It is becoming increasingly evident that measurements are a key element in lowering not only capital expenditures but also operating expenses. Ronnie Pedersen, project manager of our development project with Google, emphasises that offshore wind turbines and foundations will be strategically monitored in the future, and therefore it is vital to have full control of different sources of real-time data.
Ramboll is expanding the smart service by providing a cloud-based data storage and execution platform that systematically run data to facilitate decisions on, e.g., life-time extensions or inspections.
“This can be used to offer new real-time insights into the health of the structure and further optimise future structural designs, for instance, by further minimising the undesired conservatism in the calculations, which stems from the complex interaction between wind turbine and turbine foundation,” says Ronnie Pedersen.
The system used for the long-term storage of the measurement data must have two properties. It must first be able to scale to the large volumes of data produced and also allow fast queries to be performed on the stored data. This is achieved with Google Cloud Platform. Google’s systems offer the added advantage that the data storage has built-in support for secure, transparent user access control. This can be useful in allowing partners and certifiers direct access to subparts of the data.
“Google is committed to carbon neutrality in our own operations, and we are very pleased that Ramboll has chosen Google Cloud Platform to help leverage data to improve offshore wind efficiency,” says Mads Kjærsgaard, Sales Manager for Google Cloud Denmark and Iceland. “We look forward to being a part of Ramboll’s efforts to improve adoption of green energy.”
Based in the Nordics, Computas delivers services and solutions for technological innovation. The company is one of the largest Google Cloud Platform Partners in Europe, and specializes in cloud solutions, data science and machine learning.
“Computas is extremely proud to assist Ramboll in realizing their vision to increase efficiency and lower costs in offshore wind industry,” says Lars Brantshaug, VP Sales for Computas Denmark. “This is a truly inspiring innovation project in making offshore wind a sustainable industry.”
Optimising with digital waves
There are other smart ways of improving offshore wind projects. Ramboll has constructed a digital wave tank that uses computational fluid dynamics (CFD) to help design wind turbine foundations and substations that are faster and cheaper to construct and more cost-efficient to operate, because they are based on real-world data, simulations and assessments.
Ramboll has worked with CFD for over 20 years, initially on projects for building interiors where the technology helped to dimension ventilation systems and improve fire safety. This gradually extended to other areas like urban planning in Hong Kong, baseball stadiums in the USA and advanced railway and high-speed train projects in the Nordics.
The digital wave tank and other CFD performance simulation models were used to optimise 44 offshore wind turbine monopiles for the Norther Offshore Wind farm in Belgium. This generated more than one million euro in construction savings – because the solution used less steel and avoided on-the-job redesign – plus life-cycle maintenance costs went down 75%.
Written by Michael Rothenborg.
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