the simplicity and complexity of wind: an engineer’s tale · the simplicity and complexity of...

The simplicity and complexity of wind:an engineer’s tale

Joint Lecture at The Royal Society of Edinburgh

16 March 2010

Speaker: Ian IrvineSgurrEnergy

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The Royal Society of EdinburghThe Royal Society of Edinburgh (RSE) is Scotland’s National Academy of Science & Letters. It is an independent body withcharitable status. The Society organises conferences and lecturesfor the specialist and for the general public. It provides a forum forinformed debate on issues of national and international importance.

Its multidisciplinary fellowship of men and women of international standing provides independent, expert advice to keydecision-making bodies, including Government and Parliament. The Society’s Research Awards programme annuallyawards over £2 million to exceptionally talented young researchers to advance fundamental knowledge, and to develop potential entrepreneurs to commercialise their research and boost wealth-generation. Among its manypublic benefit activities, the RSE is active in classrooms from the Borders to the Northern Isles, with a successful programme of lectures and hands-on workshops for primary and secondary school pupils. The Royal Society of Edinburgh, working as part of the UK and within a global context, is committed to the future of Scotland’s social,economic and cultural well-being.

The Royal Acacemy of Engineering"As Britain’s national academy for engineering, we bring together the country’s most eminent engineers from alldisciplines to promote excellence in the science, art andpractice of engineering. Our strategic priorities are to enhance the UK’s engineering capabilities; to celebrate excellence and inspire the next generation; and to lead debate by guiding informed thinking and influencing public policy."

Strategic PrioritiesThe Academy’s work programmes are driven bythree strategic priorities, each of which provides akey contribution to a strong and vibrant engineeringsector and to the health and wealth of society.

Enhancing national capabilitiesAs a priority, we encourage, support and facilitate links between academia and industry. Throughtargeted national and international programmes, we enhance – and reflect abroad – the UK’s performance inthe application of science, technology transfer, and the promotion and exploitation of innovation. We supporthigh quality engineering research, encourage an inter disciplinary ethos, facilitate international exchangeand provide a means of determining and disseminatingbest practice. In particular, our activities focus on complex and multidisciplinary areas of rapid development.

Recognising excellence and inspiring the next generationExcellence breeds excellence. We celebrate engineeringexcellence and use it to inspire, support and challenge tomorrow’s engineering leaders. We focus our initiativesto develop excellence and through creative and collaborative activity, we demonstrate to the young, andthose who influence them, the relevance of engineeringto society.

Leading debateUsing the leadership and expertise of our Fellowship, weguide informed thinking; influence public policy making; provide a forum for the mutual exchange ofideas; and pursue effective engagement with society onmatters within our competence. The Academy advo-cates progressive, forward-looking solutions based onimpartial advice and quality foundations, and works toenhance appreciation of the positive role of engineering and its contribution to the economicstrength of the nation.

The Royal Academy of Engineering and The Royal Society of Edinburgh Lecture

The simplicity and complexity of wind: an engineer’s taleThe energy in the wind is generated by the Sun heating the Earth’s atmosphere, which then cools as theEarth rotates on its axis, forcing movements of large volumes of air across the globe; a simple behaviourthat will persist for as long as conditions on Earth allow.

Humans have been utilising this energy for thousands of years and have used increasingly technical developments to extract its power efficiently. However, despite the general development of engineering capability, there is still some way to go towards optimising fully the potential of wind energy conversiondevices.

Ian Irvine, co-founder and Technical Director of SgurrEnergy, will explain why he believes the origin of thisissue is the character of wind and a general lack of understanding of the complexity of this renewable energy resource. Ian will also explain his belief that remote sensing will enable wind energy technologyto increase its contribution to carbon emission reduction.

In the final part of his presentation Ian will talk more generally about how developments in renewable energy technology can be used to generate sustainable energy at the levels needed to maintain the simple, relatively well-understood cycle of the wind.

Contents

SgurrEnergy 4

Biography - Ian Irvine 5

Wind Energy 6

Case study - Galion Lidar 8

Case study -SgurrTrend 10

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SgurrEnergy SgurrEnergy is a leading independent engineering consultancy specialising in renewable energy projects worldwide. With a highly qualified team of over 100 consultants and engineers, SgurrEnergy has a significant trackrecord in the wind, solar, biomass and marine energy sectors. To date, over 40,000MW of renewable energy development has been assessed internationally; a figure that continues to grow.

Founded by Ian Irvine and fellow Director Steve McDonald in 2002, SgurrEnergy is headquartered in Glasgow, Scotland and has

international offices in China (Beijing), the United States (Portland, Maine), Canada (Vancouver), India (Pune), France

(Paris) and Ireland (Wexford). With a wealth of internationalexperience, the company has worked in many of the most

challenging environments towards its aims of bringing en-vironmental, economic and social benefits to communi-ties around the world through renewable energyengineering.

Trusted by world-leading utilities, developers, independent power producers and financiers,

SgurrEnergy provides full-project life-cycle engineering services for renewable project development, delivering at

each phase of a project from early stages of feasibility andplanning through implementation and into operations and

maintenance. With an eight-year track record of successful engineering consultancy and a wealth of expertise and unparalleled

understanding of wind farm development within the company, SgurrEnergy is in an ideal position to develop innovative products that could bring greater efficiency to wind farmdevelopments. In 2008, the company moved into product development with the launch of Galion Lidar, a remotesensing device for measuring wind data.


Wind turbine erection onsite in Inner Mongolia Wind farm site in the Philippines

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Ian Irvine, Technical DirectorIan Irvine has been in the renewable energy industry for 25 yearsand, as an experienced engineer, has become an internationally recognised expert in the sector. With a background in mechanical engineering, he has been involved in a wide range of renewable projects, from small community projects to multi-GW renewable energy portfolios. He is particularly skilled in technical assessments, front-end project development and innovation.

As SgurrEnergy’s Technical Director, Ian was engaged through theChina Renewable Energy Scale-up Programme (CRESP), which isfunded by the World Bank and the Global Environment Facility toevaluate multiple offshore wind farm sites along the Fujian coast in China.

As a result of this project, SgurrEnergy was further engaged to advise on the offshore wind farm potential along a further 10,000 kmof the Chinese coast. Appointed by the EU–China Energy & Environment Programme to work in partnership with the China Meteorological Administration (CMA), SgurrEnergy is training localexperts on offshore wind farm assessment methodology and project development techniques. As part of the project, SgurrEnergy andCMA have produced a handbook for the offshore wind farm development process in China. The results ofthese projects form a central part of the Chinese Government’s strategy for developing offshore windprojects in China.

In addition, Ian has financial due diligence assessment and ongoing lender’s engineer experience onmajor offshore wind farm projects, including London Array, Lynn and Inner Dowsing, Borkum West II, NordSee Ost, Ormonde, Q7/Princess Amalia, Horns Rev 1 and 2, Yttre Stengrund, Samsø, Rødsand 1, ScrobySands, Kentish Flats, North Hoyle, Barrow, Thornton Bank, Thanet, Greater Gabbard, Sandbank 24, KentishFlats.


Ian Irvine, SgurrEnergy

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Wind Energy As climate change and decliningsupplies of fossil fuels become increasingly pressing issues, it isbecoming widely acknowledgedthat we need to derive more ofour energy from clean and renewable sources such as windenergy. However, wind energy isnot without its difficulties, andkey amongst them is the diffi-culty of predicting accurately thewind resource and character at a potential wind farm site. It isoften said that the wind is free,which is true, but the flipside tothis coin is that it is also variableand difficult to predict. Further-more, the capital costs of constructing wind projects is relatively high, so it is essential to

have accurate revenue (i.e. wind resource) predictions in order to gain access to financing.

As a result, estimation of wind resource and character is the single largest risk factor when consideringthe viability of a wind farm project. The energy output of a wind farm installation is typically proportionalto the square of the wind speed. So the difference in energy output between a 6m/s project and a 7m/sproject is about 35%, even though the difference in wind speed is only about 17%. Given this level ofsensitivity, it is therefore crucial that a developer does as much as possible to minimise uncertainty in assessment of the wind resource. The wind character will have a significant impact on operational costsand turbine life.

When considering wind resource, it is important to realise that it varies both in time and space, and anywind assessment campaign must address both of these issues. Looking first at time, wind speed variesfrom one second to the next, and from one year to the next. Standard deviation in mean annual windspeed is about 6% in the UK, which would result in a variation in energy output of around 12%. To minimise the uncertainty associated with variation in wind speed over time, the ideal solution would beto measure the wind speed at a proposed wind farm location for a very long time, for example 25 years,before building the wind farm. However, this is not generally practical, and so wind speed is typically measured for a period of a year, and the data collected is then corrected to a long term valuethrough a procedure called Measure–Correlate–Predict (MCP). This involves correlating the wind datameasured on site with concurrent data from a long-term met station and effectively allows one year ofdata to be extrapolated to a long-term value, reducing the uncertainty associated with temporal variation.

Turning now to variation in wind speed with space, wind flow is affected by the local topography of theland, roughness effects such as areas of forestry or houses, and obstacles such as single buildings. In


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addition, it is also affected by the wind turbines that make up a wind farm. A number of software packages have been developed to model wind flow, allowing single-point wind measurements from ameasurement mast to be extrapolated across a potential wind farm site. However, these models are generally limited, and so it is strongly recommended that wind measurements are made at several locations across a wind farm site to ensure that the model is correctly calibrated and to reduce uncertainty. The conventional method for capturing wind speed and directional data has been the use of anemometer cups installed on met masts at various heights; the data is logged and analysed using computer modelling techniques to build up a picture of the entire site. This allows consultants to thendesign the wind farm and position the wind turbines.

However, Lidars are quickly becoming the tool of choice for this type of work. Lidars use a laser to measure wind data, and compared to a mast they are highly portable, can measure at various heightsand are easy to deploy.

SgurrEnergy’s Galion Lidar is the second generation of this mature technology, transforming wind measurement campaigns and allowing a far greater understanding of this complex energy source.

A strong wind measurement campaign accompanied by good analysis and modelling will typically resultin an uncertainty in the energy yield prediction of around 10%. This could make it easier to secure finance and the best possible terms.


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Case study – Galion Lidar

Remote sensing – the data solution A Galion Lidar campaign and analysis allows the remote detection ofwind conditions using lasers and gives measured data where onceonly model approximations have been possible. This is revolution-ising the ability to predict the wind resource and wind character atproposed wind farm sites and enabling existing wind farms to operate more efficiently.

This breakthrough device allows wind farm developers to assess accurately the wind resource at any proposed site over a massively extended range in comparison to previous devices and methods,tackling issues such as complex or forested terrain. For the very firsttime, it is possible to measure accurately the wake created in the windafter it has blown through turbine blades. This is particularly useful forturbine spacing at the design phase. The importance of this knowledge, which has previously been available only using model approximations, cannot be underestimated. With Galion measurement, turbines can be sited confidently, taking into accountthe optimal wind resource, and the effects of obstructions which impact the wind flow on proposed sites. This ensures that the

maximum amount of energy is derived from the site and ensures optimum developments with regard tooperational costs and operating life.

Galion Lidar deployed on a Scottish wind farm

Scan over complex terrain to visualise the effects on wind flow Survey of multiple potential turbine positions from a single deployment


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Independently validated by Risø DTU at its Høvsøre facility against its 116-metre instrumental mast, GalionLidar has the ability to measure wind speed anywhere within a two-kilometre radius of the device, allowing it to produce scan images showing the wind flow over an entire wind farm area. This kind of information allows a developer to predict far more accurately the wind speeds across the wind farm site,reducing the uncertainty in the energy yield prediction, particularly for complex sites where steep slopesor forestry may be inaccurately modelled, thus fully characterising wind flow at a target site.

One of the most significant features of Galion Lidar is the steerable beam, allowing total freedom to selectcustom scans most suitable for any given application. So, for example, multiple proposed wind turbine locations can be surveyed from a single Lidar deployment, leading to cost savings and an improved dataset. Previous Lidar devices for wind power applications are restricted to a single scan function that measures wind in the 200-metre space immediately above them. The freedom to choose other customscans allows the Galion to acquire measurements anywhere within its two-kilometre range. For the firsttime, Galion allows full visualisation of a potential wind farm site. This ensures the site is developed optimally and the maximum amount of clean, green wind energy is extracted.

Understanding wind flow in operational wind farmsThe propagation of wind turbine wakes has been a subject of intense study, due to their implications forturbulence, fatigue loading and power production in arrays of turbines. The Galion allows the direct measurement and dramatic imaging of wind turbine wakes with previously unattainable degrees of precision and detail, allowing us to understand their formation and propagation and mitigate their impacton other turbines as never before. Galion can capture multiple turbine wakes in a unique way.

Galion deployment Galion is currently undertaking a measurement campaign at an existing wind farm in Scotland, assessing the applicability of cutting-edge methods that will inform future industry standards.

The results of the deployment to date show a more precise and revealing assessment of turbine performance than that achieved by assessment of operational power curves by plotting wind speed athub height. This allows genuine turbine-related issues to be differentiated from simple nacelle-mounted sensor errors, and the assessment of wind flow characteristics that have a negative impact on wind turbine performance and condition. The work being carried out at this wind farm will ultimately allow amore focused, better performed operations and maintenance strategy, leading to higher revenues andlower operational expenditure for the wind farm operator.

Galion can uniquely capture multiple turbine wakes Galion deployed on a Scottish wind farm


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Case study – SgurrTrend

The operation of wind power assets presents a unique set of challenges and, if these are to be met andsuccessfully overcome, some cherished paradigms must be discarded and novel approaches adopted;otherwise the immense potential of wind power may go at least partially unrealised.

In response to this, SgurrEnergy has introduced SgurrTrend, a suite of powerful software tools developed in-house which build on SgurrEnergy’s extensive experience and expertise, with staff performing routine analysis and review of the operational performance of a number of wind farm sitesacross the globe.

Operation and maintenance of wind farm sites The operation and maintenance of established modes of power generation such as coal or hydro, usually entails monitoring the performance and condition of a relatively small number of turbines installed in the well-regulated environment of a turbine hall close toinfrastructure, and exploiting a controlled, relatively non-variable resource.

In direct contrast to a turbine hall, wind power sites are a considerablydifferent animal. By its very nature, the wind itself is highly variableand anintermittent resource to which the assets respond in a neces-sarily highly complex manner and which has characteristics such as turbulence which can have a damaging effect on the assets.

As wind turbines are installed in progressively more remote, inaccessible and hostile locations and as the industry continues itsmove offshore, where the consequences of component failure anddowntime are catastrophic and intolerable, one can no longer afford to be reactive when it comes to keeping the turbines turning,and the need to take a different approach becomes compelling. Yetthe greater difficulty of performing inspections makes proactive

measures of the sort that would be implemented at conventional facilities often prohibitively expensive.

These considerations have placed a greater emphasis on the analysis of SCADA data. SCADA (Supervisory Control and Data Acquisition) systems enable operators to interact with the assets they handle, and routinely produce and store large quantities of operational data. Extracting valuable and necessary performance information from these data has hitherto been regarded as onerous and


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expensive. It is in precisely this area that innovative methods are being developed to deliver the benefitsthat overcome the limitations of conventional methods and enable the effective operation and mainte-nance of large arrays and portfolios of wind power assets.

The key impediment has been the rapidity with which anomalous performance can be identified, andthe extent to which this process can be automated, to allow analysts to focus their attention in the mostproductive and cost-effective manner where it will make the most difference. Conventional plant, with itssmall number of well behaved and relatively unstressed assets, has not driven innovation in this area,since traditional methods have been adequate.

However wind power, where rapidly identifying anomalous performance and warning signs such as signatures of incipient component failure in the data can seem like finding a needle in a haystack, haswitnessed the development of paradigm-altering techniques, such as Response Deficit Analysis, whichlink disparate information and highlight asset behaviour of interest.

SgurrEnergy implement these techniques in a suite of software tools called SgurrTrend which are used tosupport the delivery of wind turbine performance monitoring, review, assessment, and auditing services,support management, operation and maintenance functions, and prioritise inspection and repair. Response Deficit Analysis, as implemented using SgurrTrend, radically accelerates and automates theidentification of anomalous performance, reducing the time involved from days to minutes to allow analysts to progress immediately to determining what measures will secure reliable and optimised performance.

SgurrTrend onsite in China SgurrTrend enables analysts to rapidly characterise wind turbine performance, identify operational issuesand consequently focus their investigation in the most cost-effective way.

Notable among the sites benefiting from this service is a 40-turbinewind farm in the North of China. SgurrTrend reviews of the operational site have enabled us to provide cost-effective recommendations for maximising plant revenue and optimising performance. These have saved the client from additional expenditure by minimising routine maintenance, highlighting plantissues that require immediate attention and prioritising systems for inspection. By utilising operational data already routinely acquired by the plant’s SCADA system, SgurrTrend represents a zero risk approach to performance optimisation.


Shirley Chen onsite at Bailingmiao wind farm,Inner Mongolia

Contact:The Royal Society of Edinburgh – www.royalsoced.org.uk – 0131 240 5000The Royal Academy of Engineering – www.raeng.org.uk – 020 7766 0600

Sgurr Energy – www.sgurrenergy.com – 0141 227 1700National Science and Engineering Week – www.britishscienceassociation.org/web/

The Royal Academy of Engineering/The Royal Society of Edinburgh

Joint Lecture 2010ISBN No 1-903496-53-5

© The Royal Academy of Engineering:March 2010

The Royal Society of Edinburgh, Scotland’s National Academy, is Scottish Charity No SC000470The Royal Academy of Engineering is Registered Charity No 293074

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