LAST CALL: Offshore Cabling Conference

Berlin, 22/02/2012 – One of the key elements in the successful construction of an offshore wind park is the skilful installation of cables – a complicated task that is often subject to huge repair costs. Cable damage causes over 70% of all insurance claims on installed wind parks, which shows that there is great need for improving the installation technology of cable installation. Meet OEMs and leading experts on IQPC’s conference on Offshore Cabling, 26 – 28 March in Bremen to discuss innovative technologies and financial planning strategies.

Sign up now, as there are only a few placed left. Visit the website for more information or contact us at info@iqpc.de

Interview with Thorsten Schwarz, Managing Director at Norddeutsche Seekabelwerke (NSW)

Thorsten Schwarz explains in an interview with Joanna Scheffel from IQPC the background of NSW and the best method to bury cables in the sea ground – and the difference of cabling in the North Sea and the Baltic Sea. In his opinion, burying cables via the ploughing technique puts by far the most stress on the cable itself.


Interested in reading the full interview? Access the interview here.

Rotor Blades – Lightweight Design and Optimized Manufacturing

Wind power is the fastest growing segment in the energy sector. In the offshore wind industry, lightweight structures for extreme offshore conditions and loads are needed urgently. Rotor blades represent up to a quarter of the investment in a wind turbine. IQPC’s International Conference on Advances in Wind Turbine Rotor Blades, 13 - 15 February 2012 in Bremen, is the first event to set industry benchmarks on blade design, materials and manufacturing processes.

The main topics of the conference include:

• Economic challenges of rotor blade development
• Structural design and aerodynamic performance (two OEM presentations)
• Testing of blades, such as virtual testing and in-field validation methods
• Improved and new materials for blades, such as natural fibre, glass fibre or carbon fibre

Additionally, participants are offered two interactive workshops on February 15, 2012. Discuss the structural blade design and CFD applications for blade design with experts from the Fraunhofer Institute for Wind Energy Systems and the University of Stuttgart.

 

The conference will give participants the chance to identify the key challenges in blade manufacturing technologies and learn about advanced design concepts for increased energy yield. Experts from OEMs such as Siemens Wind Power, GE Wind Energy, Vestas Wind Systems and SGL Rotec GmbH will offer valuable first-hand information.

 

Please visit the website for more information and conference details.

The Innovation and Design of Rotor Blades for the Future

European renewable energy targets continue to fuel the wind turbine industry, with the development of the offshore market pushing the demand for even larger turbines. Some of the designs currently in use have rotor diameters in excess of 120 metres, and the blades are required to perform efficiently under extremely turbulent conditions.

Rotor blades can account for 20-25% of the overall cost of a wind turbine, so it is essential that the blades are efficient and provide long service with little maintenance, to ensure their cost-effectiveness. Manufacturers are constantly developing the production process as new methods and technology are integrated. The move towards mass production to meet the demand of the growing offshore market, and the opportunity to manufacture close to site, offers the potential to reduce the cost of rotor blades significantly.

Rotor blade design concepts

Aerodynamics is crucial in rotor blade design; in the past blades have been designed on the basis of aviation airfoils, but these airfoils are intended for plane wings which are placed under entirely different wind flow conditions to turbine blades (¹). Most blade manufacturers use their own customised design for turbine blade airfoils, and are continually developing the technology behind them.

The aerodynamic design of a blade dictates its width, thickness and twist. And the key challenge to manufacturers is to find a compromise between air flow and blade strength to optimise performance and efficiency. In pure terms of aerodynamics, the perfect blade design would see a blade which is thick, wide and very long. In reality, this is not viable as the blade would put far too much strain on the turbine, and could strike the tower upon rotation. The strongest type of blade would be one of a circular structure, but this is equally implausible as such a blade would have minimal lift, and would not be suitable for producing energy from wind power. These extreme examples indicate why it is so important to find the best balance between air flow and strength in blade manufacture to improve efficiency.

One of the world’s leading blade manufacturers, LM Wind Power, have sold over 130,000 blades equivalent to a capacity of 43 GW; and more than one in three wind turbines in the world is fitted with their blades (¹). They use several innovative design concepts to improve performance, and are at the forefront of glass fibre development to produce lighter more efficient blades.

One unique feature in the design of LM blades is the pre-bending process, which means the blades flex towards the wind once they are mounted and are not subject to loading (²). Clearance of the tower is essential in blade design, and the tip to tower distance is critical.

Interested in reading more about rotor blade design concepts? Find out more here.

References:

(1)  http://smart-blade.com/research/airfoil-design.htm

(2)  http://www.lmwindpower.com/Blades/About/Business%20area.aspx

Large-Scale Hydrogen Underground Storage for Securing Future Energy Supplies

by Fritz Crotogino & Sabine Donadei, KBB UT, Hanover / Germany & Ulrich Bünger & Hubert Landinger, LBST, Ottobrunn / Germany

Introduction
In recent years the role of hydrogen in future energy scenarios has moved somewhat into the background. Now its significance is being highlighted even more as it may play an important role during and after the transition from fossil fuels to renewable energy sources concerning two areas in particular.

ENERGY INDUSTRYNERGY INDUSTRY
The energy industry is facing the need to store extremely large quantities of energy for long-term to seasonal periods in order to adapt the fluctuating and non-dispatchable energy production from wind and solar resources to the actual demand, which is no longer feasible using conventional technologies. In today’s fossil-based energy industry, seasonal fluctuations, strategic reserves, and compensation of shortages and shut-downs are largely balanced out by the storage of fossil fuels (e.g. Germany and France both have reserves covering around 2 months of demand). With a reach of only around 1 hour (Germany), today the storage of electrical energy plays a very subordinate role. The possibility to outsource the storage capacity to fossil fuels will decrease more and more in a future electricity-based energy industry, i.e. the long-term storage capacities for electrical energy will have to be much longer than 1 hour.

In recent years pumped hydro and compressed air energy storage (CAES) systems were almost exclusively seen as suitable methods for balancing out fluctuating wind and PV feed-in into the transmission grids. In contrast, the latest investigations - and particularly the comprehensive study published by VDE /1/ have identified the limitations of these storage technologies, particularly with respect to total storage capacities. Hydrogen alone can facilitate the storage of large quantities of energy to balance out long periods of poor wind power supply and seasonal fluctuations. Hydrogen large scale storage will be the only means in the long term to provide electrical energy in quantities and at a quality level consumers are accustomed to, in parallel to the downscaling of major capacities from fossil power plants and nuclear power stations. Furthermore, the relevant large volumes which need to be stored can most likely only be accommodated underground in geological formations – primarily in man-made salt caverns.

SUPPLYING FUEL CELL VEHICLES WITH HYDROGENUPPLYING FUEL CELL VEHICLES WITH HYDROGEN
The limited range and low storage capacity of battery electric vehicles as well as the limited availability of biofuels limiting its long term use to heavy duty transport such as trucks, rail and aircraft, require the use of hydrogen powered fuel cell vehicles for a wide range of vehicle segments. After a transition phase, hydrogen needs to be mainly produced from renewable electricity such as wind and solar power. Also for the transport sector it will be necessary to balance out seasonal fluctuations and to build up reserves to prepare for shortfalls, etc.

Most of today’s infrastructure investigations on future hydrogen supply have either addressed the development of hydrogen demand or the build-up of hydrogen refuelling stations including onsite hydrogen storage capacities as well as onboard hydrogen storage.

The full paper is available as a free download here. You will also find more interesting papers in english and in german language.

Imressions of Drivetrain Concepts for Wind Turbines Conference 2011

This year's "Drivetrain Concepts for Wind Turbines" conference 17 - 19 October in Bremen was again a huge success! More than 100 industry experts met in Bremen to discuss the latest trends and developments in drivetrain concepts for wind turbines. Apart from high-level speaker presentations, attendees benefited from numerous networking opportunitites, and enjoyed an exclusive evening reception at the main hall of Bremen.

Have a look at the impressions video of the conference:

IQPC thanks all attendees, sponsors and media partners for this successful event. The next conference is currently in preparation. More information to follow soon. See you next year in Bremen!

All at sea – Grid Integration of Offshore Wind Energy

Offshore wind power is set for a strong future, not least in Germany where the phase out of nuclear power will see the country lose around a quarter of its generating capacity in the next decade. Germany is already leading the way in wind power on the continent with 27,214 MW of installed capacity and the government is looking to increase this figure further as it favours wind over other renewables.

Although much of this is currently installed onshore, 24 offshore projects have been approved, bringing with them a generation capacity of 7,000 MW. Overall, Europe is expected to see its wind power capacity triple by 2020. This growth brings with it the need to future proof the transmission system, allowing it to cope with the intermittent nature of wind power, while also extending the distribution network to integrate the growing number of wind farms with greater generation capacity located in harsher environments further offshore.

Future Demands on the Grid
Germany is, of course, not the only country priming itself for future success in the offshore wind sector. Across the EU there are currently 100 GW of wind power projects at some stage of planning, according to figures from the UK's Department of Energy and Climate Change (DECC), and this is ushering a new era of greater collaboration in the distribution of electricity. Incidences in recent months in Germany, where wind output has been particularly high, has left providers paying to remove power from the grid. This is a situation the industry does not want to see but may increase as wind capacity increases. With this in mind, among other issues, the UK, Ireland, Sweden, Denmark, Germany, the Netherlands, Luxembourg, France, Norway and Belgium last year signed an agreement on the North Seas Offshore Grid Initiative. The distribution system would allow power to be transferred from one country to another through subsea cables, while also allowing offshore wind farms to be connected to the grid. The DECC sees the relationship between the countries as being synergetic, giving the example of the UK sending its wind power to Norway to power its hydroelectricity stations when there is a surplus, and Norway delivering power back when wind output is low.

Interested in learning more about this topic? Check out more articles here.

The requirements for wind turbines and services for grid code compliance

The advancement in offshore wind power technology has led to larger turbines and larger wind farms being deployed throughout Europe. Where previously wind farms had been thought of as single distributed power generators, they must now be considered as integral components of the overall energy supply system, and be subject to the same regulations as other types of power generation.

The European Wind Energy Association (1) estimates that by 2020 between 14.4% and 16.7 % of the EU’s electricity supply will be sourced from wind energy, both on land and offshore. The European Commission’s energy strategy for Europe (2) suggests that up to 12% of this will be supplied by offshore wind farms.

Due to the increase in the size of wind farms, and the requirement of Europe’s TSO’s (Transmission System Operators) to integrate them into the network, grid code compliance rules have been implemented to ensure that offshore wind farms contribute to the system, and behave in the same way as conventional generators. Before connection to the grid, wind turbines and wind farms must certify that they comply with regulations surrounding frequency dependant active power supply (frequency control), Voltage control – both steady state and dynamic, Voltage dependant reactive power injection and absorption, and fault ride through stability.

While the European grid as a whole must undergo rapid redevelopment to access and integrate offshore wind power, the responsibility of turbine manufacturers and wind farm construction companies is to ensure that their equipment, when connected, has a positive impact on the overall system.
Grid code requirements for wind turbines and wind farms

The European Wind Energy association is working towards the harmonisation of grid code compliance across Europe, and in late 2009 issued the first template for a generic grid code (3) format for wind power plants. The organisation is in continued collaboration with the EU and with Europe’s TSO’s to develop a fully continental-wide harmonised grid code.

Want to learn more about grid integration of offshore wind energy? Check out further articles here.

References
(1) http://www.ewea.org/index.php?id=196
(2) http://ec.europa.eu/energy/publications/doc/2011_energy2020_en.pdf

(3)http://www.ewea.org/fileadmin/ewea_documents/documents/publications/091127_GGCF_Final_Draft.pdf

The Future for electricity transmission in Europe and the integration of wind power

The challenges facing the integration of wind power

To fully integrate wind power into the grid there needs to be a systematic upgrade of the existing infrastructure, as well as the introduction of new technology and network management techniques. Furthermore the development of offshore super grids may be the most effective way of sourcing renewable energy from wind power and distributing it efficiently.

Transmission capacity must be significantly increased to accept the introduction of wind power, and some of the measures that can be taken include utilizing existing transmission lines to their maximum capacity, investment in the construction of new transmission lines, and investment in other areas of the network and the upgrade of assets.

Existing lines can be maximised to their full potential by operating them at higher capacity, which would need to be supported by temperature monitoring to ensure network integrity. The cross border exchange of power between countries can also be streamlined and seen as a measure to ease congestion. Automatic generation control systems, or managed demand-side control systems may also be options to alleviate congestion and control the network, but these are seen as short term options as they are not efficient in terms of energy generation.

The most obvious form of network upgrade is the construction of new, high voltage power lines. In many cases this is unavoidable to connect offshore wind farms to the grid due to their location and the lack of existing transmission lines. One of the challenges facing TSO’s here is the fact that planning permissions for new lines often takes 10-12 years, much longer than the planning permissions for offshore wind farms. TSO’s are faced with making early decisions on the proposals of new lines to ensure they are in place in time for when a wind farm becomes operational. This presents a risk for the industry, as at the time of planning it cannot be assured that the construction of a particular wind farm will actually go ahead.

Investment in assets and other areas of the network is another possibility that will aid the integration of wind power and realise increased power supply and ease of exchange with other countries. This may include adding transformers to existing substations to increase load capacity, replacing line conductors with high temperature conductors or adding second circuit lines to towers, or replacing transmission lines with higher voltage lines and increasing capacity.

Increased transmission capacity is vital for the integration of wind power to the grid, but equally the EU has taken steps to ensure fair access for wind power. The ‘third liberalisation package’ stipulates that TSO’s ensure that there is sufficient transmission capacity to integrate renewable energy into the grid. While this can present a problem for TSO’s in terms of planning permissions in regard to constructing new lines to connect to wind farms, in the interim the problem is usually solved by ‘connecting and managing’ where grid capacity is limited.

The development of super grids

According to the organisation ‘Friends of the Super grid’, a super grid can be defined as, "An electricity transmission system, mainly based on direct current, designed to facilitate large-scale sustainable power generation in remote areas for transmission to centres of consumption, one of whose fundamental attributes will be the enhancement of the market in electricity".(5)

Source: Friends of the Super grid phase 1 proposal (⁶)

The development of an offshore super grid is becoming the most likely route towards harnessing renewable energy from wind power. The creation of ‘supernodes’ which will collect, integrate and distribute electricity will enable full integration in the long term future. The phase 1 example of the North Sea super grid proposed by the ‘Friends of the Super grid’ above, shows how the initial development may look. With the power generated by offshore wind estimated to be over 150MW by 2030 by the EWEA (European Wind Energy Association), a network connecting countries via the North Sea will enable supply and distribution to areas of demand, and ease cross-country distribution significantly.

Looking towards 2050 and a zero-carbon society, it is estimated that large wind fired power stations will be the building blocks of the super grid, with up to 500MW of capacity. This will enable the connection of several wind farms to one power station which can control the variable power output and integrate it fully via the network.

Harmonised HSE standards for the offshore wind power industry

The offshore wind energy industry can still be considered a fledgling industry, and as such there is little experience to draw on in relation to health and safety. The specific environment that an offshore wind farm presents requires its own dedicated health and safety standards. Furthermore the industry is set to grow substantially in the coming decades, so the development of health and safety procedures will need to be an ongoing process to ensure that best practice is consistently carried out, and standards do not become quickly out-dated.

Health and safety regulations impact on everyone involved in an offshore wind farm project including developers, manufacturers, suppliers, consultants and employees. With so many contributors, from several different countries involved in any one project, a harmonised health and safety standard across the industry is widely accepted as a necessary step in the development of wind power as Europe’s prominent energy source.

In the current climate, each country that has offshore wind farms within its waters has its own regulatory authority, which sets out its own regulations and requirements. There is a desire amongst the executive bodies to communicate and develop an agreed standard throughout Europe, and several studies have been undertaken to collate data in respect of offshore incidents and issues to aid that process.

General health and safety legislation and legal requirements

Some of the general health and safety laws which can be applied to the offshore wind power industry are detailed in this section, although none are specifically written for the industry (1). In practice, workers on offshore wind farms are more likely to follow the regulations set out by the company by which they are contracted.

The Energy Act (LOV 1990-06-29 nr 50: Act on the generation, transmission, trading, distribution and use of energy etc). The act is applicable to electrical energy and its generation, transmission, trading and distribution on land to ensure that the activities are undertaken in a socially efficient manner. Much of the act regards the applications and issuing of licences for the development of electrical equipment. In this respect it may affect the offshore wind industry, although little pertains directly to health and safety.

The Ocean Energy Act (LOV 2010-06-04 nr 21: Act on renewable energy production at sea) came into force in June 2010, and is applicable to the utilization of renewable energy at sea; including wind, waves and tides. It also regulates the conversion and transmission of electrical energy offshore. The main purpose of the act is to facilitate the use of these resources in line with social objectives, and to ensure that any offshore installations are planned, constructed and disposed of in the interests of the environment, energy, and business. One requirement is that the installation, the operation, and the decommissioning of offshore energy plants should be such that “a high level of health and safety” can be maintained and developed in accordance with technological advances.

IEC 88/379/NP: Standard for Floating Offshore Wind Turbines: The new proposal was first issued in October 2010, since when the title has been changed from ‘Standard’ to ‘Technical Specification’. While it is still only a draft, the proposal includes guidelines for floating offshore wind turbines using design concepts such as spar buoys, tension leg platforms, barges, and mooring systems. The aim of the specification is to “provide an appropriate level of protection against damage from all hazards during the planned lifetime”. It defines in detail the “principles, technical requirements and assessment procedures for the design, installation, and maintenance of floating offshore wind turbines”.

Other legislation that could concern offshore wind power in relation to health and safety would include the Employment Protection Act, and possibly the Pollution Act.

Want to learn more about specific health and safety standards for offshore environments? Click here for more information, articles, and whitepapers.

References

(1) http://www.sintef.no/upload/Teknologi_og_samfunn/Sikkerhet%20og%20p%C3%A5litelighet/Final%20report%20HSE%20challenges%20offshore%20renewable%20energy.pdf

New Health and Safety Standards in the Wind Industry

Shore wind energy is considered the most promising source of renewable energy to achieve the ambitious political target of 20% by 2020. In response, the offshore wind power industry is growing rapidly with a considerable number of large-scale projects on the horizon.

To realise these ambitious mega-projects, large numbers of highly skilled personnel is required. All wind developers are required to consider the risks that may arise in their projects during construction, operation, and final demolition. Risks can be accidents which happen when working on a wind farm.

Only recently, a wind farm worker was killed inside a wind turbine in Iowa.

The problem is: As the off/onshore wind energy industry is moving at such a pace, developers have had little time to consider the practical problems involved with these projects, but this is sure to be a crucial task if the industry is to establish a reputation of being a safe workplace.

There are a number of issues relating to health and safety that need to be addressed as wind farms move further from the shore and also into deeper water. If the industry wants to attract the best personnel and earn a reputation as a safe place to work, vital to its long term success, health and safety issues will require detailed consideration.

An industry-specific specialised health & safety standard, best practices in terms of training and equipment, good information sharing practices as well as sound HSE strategies and emergency response plans are crucial for all phases from design, construction to maintenance and repair.

Learn more about health & safety standards at the Conference on HSE in Wind Power Development in December 2011.

Recognizing The Potential Of Wind Energy As A Viable And Profitable Source Of Energy Production

B oth government and industry are searching for the most efficient environmentally friendly and sustainable methods to generate energy. Society’s love affair with cheap power has had far reaching consequences including the over reliance on fossil fuels which has had negative impacts on climate, habitats, and the lives of millions of people around the world. Though wind turbines have been used in various forms for centuries, there is now a renewed interest in the potential they have for supplying a large amount of energy.

The ability to harness wind energy for power has been attracting a great deal of attention, especially in the US. The United States now produces more wind power than any other nation, and it is predicted that by 2030, around twenty per cent of the nation’s supply will be sourced through this technology. In 2009 alone, thirty nine percent more capacity was added by the US wind power industry. This industry holds a lot of promise and a great deal of potential, however there are also obvious problems that this sector faces.

There are two main concerns regarding renewable wind energy as a sustainable source of power production. First of these concerns is sustainability. As everyone knows, the wind does not always blow. For this reason, many governments are unwilling to invest heavily in the latest turbines as there is no guarantee that they will be efficient, especially for countries that rely heavily on the export of their natural resources as their main source of economic growth. Their argument is that there would still be a need to have back up systems in place to cover any periods when there is no breeze.

The second concern is a combination of location and cost of operating a large scale wind project. Typically, the places where winds blow the most consistently are fairly remote. For example, steady winds are usually located at the top of mountains, out at sea, and across remote plains.

This is a problem that is highlighted in Texas, the country’s leading state for producing wind-power. West Texas is where the speeds and gusts are most constant, specifically on the high plains and mesas, but these regions are a considerable distance from Houston and Dallas, and installing the necessary power and utilities are difficult and expensive.

There is a lot of interest in positioning turbines offshore, though this is more expensive than onshore, data indicates that the breeze out at sea is both stronger and more constant than onshore. Offshore wind farms do make it possible to create large scale wind power facilities close to large coastal settlements, without the need for costly and extensive overland transmission cables. Also, by positioning the turbines at sea, they are not the eyesore that they would be if installed on land.

Cost of repair and maintenance at these locations can also be costly. However, new technology has enabled wind farm operators to assess, detect and repair large wind turbines without extended downtime and exorbitant costs that result in loss of profit.

This means that the positioning of wind farms isn’t as much of a problem as curbing the current governmental  mindset that fossil fuels are a necessity. The cost of extracting fossil fuels is becoming more expensive on an annual basis, yet the demand from consumers is showing absolutely no sign of decline. Sustainable power may be the solution that keeps the economy buoyant in the coming decades.

With more efficient wind turbines being constructed on an ongoing basis, the prevalence of wind technology is only going to grow. The real trick is showing both government and consumer that wind energy is cost effective as not only an efficient long term energy production method, but viable source of revenue.


Copyright © 2011 Cory Sober - All Rights Reserved. Hyperlinked material remains the property of its respective owners.  by  Cory Sober

Drivetrain Concepts for Wind Turbines Conference to return to Bremen

Despite rapid technical developments for ever larger wind turbines, high failure rates, downtime and a lack of proven track record cause time-consuming and costly repairs. At IQPC’s 2nd Drivetrain Concepts for Wind Turbines conference from 17 - 19 October 2011 in Bremen, Germany, professionals from the wind turbine industry will come together to discuss the present and future challenges in the field.

Main discussion points at the conference will include:

• Drivetrain solutions for next generation wind turbines – from gearbox to direct drive
• Achieving higher reliability, better availability and easier serviceability
• Assessing generator topologies for very large turbines for offshore wind power development
• Reducing drivetrain loads to avoid wear and fatigue in your mechanical components
• Identifying the key challenges in reducing the cost of energy (CoE) from wind power

In addition to the two main conference days, on Wednesday, 19 October, delegates can participate in interactive workshops to further their knowledge in the following areas:

• Generator systems for multi-megawatt wind turbines
• Mechanical requirements of wind turbine gearboxes
• High Temperature Superconductor technology for generators

Delegates will have the chance to discuss with experts first-hand the current challenges and developments in wind turbine drivetrains. Companies and institutions including Vestas Wind Systems A/S, E.ON Climate & Renewables GmbH, National Renewable Energy Centre, ABB Oy, the University of Manchester and Siemens Wind Power A/S have been invited to present their projects and expertise.

Further information, including articles, interviews and the preliminary program can be found at the website.

Drivetrain Solutions for Next Generation Wind Turbines

European renewable energy targets for 2020 and beyond demand that every aspect of the offshore wind turbine is scrutinised for best performance, reliability and cost-efficiency. The drivetrain, the generator and the gearbox account for 14% of failures per turbine per year, but cause 39% of all downtime for the same period.

The components, particularly in the gearbox, are subject to intense stress due to wind turbulence offshore, and are often the first parts to fail. Downtime at sea is much more pronounced, and improvement in the design of the drivetrain configuration will significantly reduce breakdowns.

The next generation of drivetrains under development include several innovative designs using direct drive systems, or hybrid systems. The trend towards direct drive is most prominent in the offshore market because of the need for greater reliability; but the challenge remains to produce a system which is light enough for the largest offshore turbines, yet cost efficient when compared with a conventional geared drivetrain.

Progression from current to future design
Wind turbines have previously used a gearbox to drive the generator, but it has always been considered a weak link. Extreme stress is placed on a gearbox by wind turbulence, and the need for larger gearboxes to service larger turbines offshore make the gearbox a vulnerable component. The cost of servicing an offshore turbine and the extended downtime has led to advances in direct drive technology, thus eliminating the gearbox and all associated failures.

Direct drive
With the generator rotating at the same speed as the turbine shaft in a direct drive system, designers have compensated by increasing the radius of rotation; using generators with a diameter of several metres. Larger generators would be needed for larger offshore wind turbines, and the problem facing developers is reducing the weight to make direct drive viable. Direct drive technology improves reliability, simplifies the nacelle assembly and helps to increase efficiency, but improvements must be made in cost efficiency and weight reduction.

Hybrid systems
Hybrid systems combine a simple and more reliable gearbox with a direct drive system. The hybrid concept has gearing at megawatt scale, but also has a large diameter generator. The nacelle has a more compact design, with the gearbox and generator giving a balanced geometry to the system. The image of the WinWind 3MW turbine below demonstrates the suitability to offshore applications, as the nacelle does not extend too far from the tower centreline.

Source:  WinWind

Future concepts
Progression towards 10MW and larger turbines requires lighter, more reliable drivetrains; and some of the technology being introduced and currently under trial will be examined in this section. It is not yet clear which type of drivetrain will best serve the wind energy industry long term; direct drive and hybrid systems will soon be joined on the market by new concepts in controlling the variable speed of the turbine.

Interested in learning more about Drivetrain Solutions for Next Generation Wind Turbines? Click here for many more relevant free whitepapers, articles, and podcasts.

Serviceability of drivetrains

The design and innovation of components and of the drivetrain assembly as a whole will lead to greater reliability, less breakdowns and less down time; but the turbines still have to be regularly serviced and maintained. Current data shows that offshore wind turbines run at an availability level of 97% on average. In practical terms this equates to four visits per year either for maintenance or repairs.

It is estimated that operation and maintenance costs could account for up to 30% of the energy cost, and manufacturers recently indicated that the cost of operation and maintenance is around £30,000 per turbine per year in the UK. The cost of offshore servicing is exaggerated by the cost of equipment, particularly vessels, as the price is driven up by competition from the oil and gas industry. Weather constraints can also affect budget and increase costs.

The current generation of wind turbines require servicing once every six months, and take between 40 and 80 man hours per year. Typically a major overhaul will be carried out every five years, and would need 100 man hours. Cancellations due to weather are estimates at 15% of service visits, so can have a significant effect on schedule and cost.

Substantial investment is being put into the development of more reliable drivetrain systems, to reduce the amount of maintenance. One area of development is computer controlled monitoring systems to react to faults, or highlight potential failures that can be rectified before they cause complete breakdown. SCADA (System Control and Data Acquisition) systems transmit signals and alarms between the turbine and the onshore control centre. Minor faults can be resolved remotely from the control centre, while more serious problems can be diagnosed early to reduce down time.

Summary
Wind turbine drivetrains (read also more here) as a concept, and at component level are undergoing rapid development. As one of the most significant contributing factors to the down time for wind turbines each year, the drivetrain is being revolutionised; along with the wind energy industry as a whole. It is unclear at this stage which technology will prove most suitable for mass production in the long term, so planning an operation and maintenance routine is a fluid process that must evolve with the design of each new system. As wind farms venture further out to sea in search of higher winds, so the turbines will increase in size, and may even exceed 10MW. The drivetrain solutions to suit that next generation of wind turbines will require their own custom maintenance plans.

Thousands of wind turbines will need to be installed over the next ten years if European energy targets for 2020 are to be met. This increase in volume of maintenance will change the landscape of the operation and maintenance sector of the wind energy industry. The cost of servicing is already at a very high level, because it requires specialist equipment, highly trained technicians and is reliant upon weather conditions.

Better reliability of the components within the drivetrain and longer service intervals built into design, can reduce the frequency of visits and cost of maintenance. Computer monitoring systems should also be utilised to relay detailed information back to the control centre, but also used interactively to diagnose and repair faults. Automated maintenance, such as filter changes, can be implemented into design to make the turbine as ‘self sufficient’ as possible.

The next round of development across Europe will see several wind farm installations, and much of the new technology being developed will be utilised to make this generation of wind turbines more economic and efficient; some of the innovations will be on ‘trail’ under very real conditions. To minimise the cost surrounding breakdowns and repairs due to unreliable components, strategies to improve the reliability and serviceability of drivetrain systems should be implemented, and should be seen as a vital part of the design process.

INTERESTED IN LEARNING MORE ABOUT THIS TOPIC? 2nd Drivetrain Concepts for Wind Turbines  Don't miss the "2nd Drivetrain Concepts for Wind Turbines" Congress, taking place 17-19 October 2011 at the Swissôtel Bremen, Germany. --> DOWNLOAD THE FREE BROCHURE

Tackling the challenges of wind turbine supply chain management

For wind turbine manufacturers, supply chain issues dictate delivery capabilities, product strategies and pricing. Global expansion and new international competitors in the market are pushing manufacturers to optimise their supply chain, align their logistics and strengthen their supplier communication. At IQPC’s conference Wind Turbine Supply Chain Management from 29 - 31 August, 2011, in Berlin, Germany, professionals in the field will come together to discuss supply chain optimisation, global operation strategies and future growth centres.

Conference day one on 29 August will focus on the areas of market analysis, new markets and supplier procurement and sourcing of components and raw materials. The following day, delegates will have the chance to discuss with experts strategies to an optimised supply chain, logistics challenges from wind turbine components.

In addition to the main two conference days, delegates can expand their knowledge in interactive workshops on the following topics:

·        Intercultural communication with suppliers and customers

·        Developing a sound supply chain risk management strategy

·        Developing most efficient logistics solutions for wind turbines

·        Building up a local supply chain in new markets
 

Further information, including the full conference program, articles and interviews, are available on www.wind-supplychain.com/PR

Stable Policies, Please, Says Wind Power Industry

The WINDPOWER 2011 Conference & Exhibition, which kicked off on Monday in Anaheim, California, and folded yesterday, started with the presence of CNN founder Ted Turner, known for his advocacy of renewable energy.
Turner took part of the opening session, which included a Q&A session with the CEO of the American Wind Energy Association, Denise Bode, who arrived on stage on a custom motorcycle inspired by wind power.

“I’ve never seen anything more clear as the case for wind, solar, and geothermal,” the media tycoon said, adding that to him embracing alternative energy is even more of an obvious decision today than launching CNN in 1980.

He also underlined the need for stable policy incentives to make the wind power industry grow. “They must be long-term incentives so we can plan intelligently,” he said.
In fact, the issue of stable policy was the main recurring topic being drummed out at the event. The industry argues that creating a predictable business environment is the key to continued growth of American wind power. It highlighted that the most immediate action is to extend what it calls the “frustratingly short-term” federal Production Tax Credit (PTC), and not wait until it expires in 2012.

by apasolini on May 26, 2011 (http://www.energyrefuge.com/blog/stable-policies-please-says-wind-power-industry/)

Reducing the costs of the offshore wind turbine supply chain

Offshore wind power as an industry is set to undergo intense growth over the next 10-20 years. The EWEA (European Wind Energy Association) has established targets of 40GW of offshore wind power production by the year 2020, and 150GW by 2030. This move towards a European grid represents a 28% annual increase in market growth; it will enable the trade of electricity between states, and cement Europe’s status as technological leaders in the wind power industry.

Meeting the first target of 40GW by 2010 requires the manufacture and installation of around 10,000 wind turbines; and there are several logistical challenges that must be overcome to achieve this aim. Offshore wind power is at an early stage of development, and there remains a necessity to streamline all aspects of the supply chain from component manufacture, to turbine design, to installation processes.


Turbines

The designs of offshore turbines were generally borrowed or adapted from their onshore counterparts; so production of offshore wind turbines had been reliant to an extent on the market growth of the onshore industry. As recently as 2008 this led to supply shortages during periods of high onshore demand. Offshore wind power, however, must be viewed as an entirely different concept to onshore wind power. With the potential for larger turbines, and no limitations on aesthetics or noise levels, manufacturers are developing specifically designed offshore turbines which could increase to up to 10MW in capacity.

Siemens, for example is currently supplying its SWT-3.6-120 turbines for use in the London Array project. The 3.6MW turbine has a 120m rotor, and the three-bladed cantilevered construction will start to produce electricity at wind speeds of 7mph. Supply and installation, however, consists of shipping the turbines from Denmark to the UK, transferring them from barges to installation vessels, before installing the turbine, the hub, and finally the blades.

To establish mass production and cost efficiency of supply and installation, there are several initiatives in development, and various logistical problems to navigate. Design is moving towards the creation of more ‘intelligent’ turbines, with advanced control monitoring and preventative maintenance. While the development of ‘simple’ turbines with fewer moving parts designed to be changed easily, will also significantly reduce costs both in terms of construction and operation and maintenance.

1 Spinner 2 Spinner bracket 3 Blade 4 Pitch bearing 5 Rotor hub 6 Main bearing 7 Main shaft 8 Gearbox 9 Service crane 10 Brake disc 11 Coupling 12 Generator 13 Yaw gear 14 Tower 15 Yaw ring 16 Oil filter 17 Generator fan 18 Canopy
Exploded view of Siemens SWT-3.6-20 nacelle, Source: siemens.com

The concept of a twin blade, downwind turbine is at design stage and could appear on the market in the coming years. Twin blades are much louder than three-bladed turbines so have not been considered appropriate for onshore development. There are no concerns over noise levels offshore, and installation could be a much quicker process as nacelles can be stacked with the rotor pre-mounted, rather than installing one of the blades at sea.

A variable speed, direct drive turbine is another possibility in the near future. Gearboxes are one of the most difficult parts to replace on a turbine, and multi-pole gearless turbines operate at a lower drive train speed which would decrease the amount of stress placed on other components. Gearless turbines are generally much heavier than those with conventional gearboxes, so designs must be produced with lighter components to reduce the weight at the top of the tower before this can become a reality.

Wind turbines are currently manufactured in such a way that any part or component cannot be replaced easily. Due to the difficulty in accessing wind farms far out at sea, and the problems of on-site repairs, it is important that purpose built offshore turbines are designed with operation and maintenance in mind. At the moment O&M is very much site specific, and as the industry learns more from existing wind farms, so the process can be standardized to create a sub-industry purely surrounding O&M. It is reasonable to expect to see swing-off systems being introduced, which will allow a spare nacelle to be fitted whilst one is undergoing a service. Preventative, automated systems that can carry out oil and filter changes without the need for humans are also on the horizon. Other initiatives such as multi-coated blades and modular drive trains will help to reduce the amount of maintenance required, and therefore reduce the amount of downtime for each turbine.

Foundations

The substructure of a turbine is one of the largest single cost factors of the overall project, and reducing the cost of construction, transportation and installation of these foundations will have a big impact on supply chain optimization. Again, much of the technology has been adapted from onshore foundations with monopoles being the most common substructure in use on offshore wind farms today. The design of specific offshore foundations, with reduced manufacturing costs is essential to ease this link in the supply chain.

Crucially, wind speed and therefore potential power production, increase greatly in deeper water. Several different concepts are being tested to enable the installation of 10MW or larger turbines on wind farms at depths of 60 metres or more.

One such design is the Sway concept produced by the Norwegian company of the same name. The floating tower can be installed in depths of up to 400 metres, taking advantage of higher wind speeds. The tower is filled with ballast, and the centre of gravity is much lower than the towers centre of buoyancy thus giving it stability. It is a unique concept as the blades face downwind, and the entire turbine can rotate to suit the direction of the wind; this optimises the amount of power generated from the wind, while at the same time reducing the stress on components. Sway claim that reduced manufacturing costs, a long life span, and the ability to support large turbines make this a viable and economic option.
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Sway concept. Source: statoil.com

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Could This Be The First Solar Powered Laptop?

While there are plenty of solar-powered peripherals that plug into your laptop to boost its battery power, we haven’t yet seen a model that runs solely on solar. Industrial Designer Andrea Ponti‘s concept for the Luce Solar Panel Powered PC could become the greenest laptop ever made.

The computer has two solar panels: One on the back of the monitor and one underneath a touch keyboard. Ideally, the two panels would be able to power the computer continuously, though it’s unclear whether this has been successfully tested. Using a laptop in the sun is far more battery intensive than indoors since the screen brightness needs to be cranked up to compete with the sun’s bright light.

One solution could be to use an electronic ink display in place of the usual backlit flat panel. Although the laptop includes a battery, the cordless design means your productivity will plummet in the evening — at least until you reach for another digital device.

The Luce, which means light in Italian, is made from a clear polycarbonate and weighs about four pounds. It was shortlisted in Fujitsu’s 2011 design competition.

There’s no word on whether Fujitsu plans to turn Ponti’s design into reality, but either way they’re not the only ones thinking about integrating sunlight into computer design. Last year Apple filed a patent for “harnessing external light to illuminate a display screen.”

In Apple’s vision, a reflector could fold down to brighten the display, and the company is rumored to be looking at integrating solar cells as well.

Design images by Andrea Ponti
Apple Patent images via Patently Apple

The Future of Offshore Wind Turbine Foundation Design

Europe leads the way in offshore wind energy with over 800 turbines in operation, providing electricity to nine countries. The power generated by offshore wind farms in Europe increased by 51% in 2010, with current installed capacity of well over 3,000 megawatts. Seen as one of the most viable renewable energy sources, wind power is primed for rapid expansion in the coming years; a further 50,000MW is in planning or under development for 2011 onwards.

Offshore wind energy is still a fledgling industry in comparison to onshore wind power, and much of the technology in use today is borrowed from land based wind farms. The challenges and demands of the installation process are, however, markedly different to onshore installations due to the difficulties of operating at sea. The logistical complexity of these installations and the costs involved in terms of construction place heavy constraints on the industry; the design challenge is to make offshore wind farms an economical and viable source of power.

Construction, transportation and installation of foundations can cost up to three times as much as the installation of the turbines, so it forms a critical part of cost analysis. There are several design concepts in research and development and at testing stage that may answer the economic questions through engineering.


Design considerations

Downtime at sea is one of the biggest cost factors involved with
offshore engineering. Construction time could be as much as doubled due to weather conditions, and as most equipment is hired, cost increase significantly. Installations are generally in two phases; the foundations are installed first, followed by the turbines. One potential way to tackle this problem is to construct as much as possible onshore, including the foundations, to limit build time at sea.

Design of foundations, particularly for deep water, is still in its infancy. The demands placed on turbine foundations vary greatly from those experienced in the offshore oil and gas industries. The technology and the knowledge of offshore installations for oil and gas can be utilized, but there are several differences that present technical and design issues. The design of wind turbine foundations must cater for dynamic response and fatigue under a working load over a long period, rather than the ultimate conditions. Generally, the vertical load is much smaller but the horizontal load is much greater. The design also needs to be considered in terms of multiple foundations as opposed to one large structure.

Deep water design

Source: NREL

The image above shows the generally accepted depths for offshore installations, which are split into three categories; shallow water, transitional water, and deep water. The vast majority of installations worldwide are in shallow water, with only a few test projects in operation at greater depths.

Deep water is by far the greatest resource of wind power, with greater wind speeds and the potential to install larger turbines. There is no agreed limit on turbine size, and a report from the UpWind Project found that rotor diameter will be up to 150m, and turbines will be 8-10MW in power in the near future. Several 10MW turbines are already in development with manufacturers across Europe.

The design challenge is to develop substructures or floating platforms to support high power turbines; moving away from the current designs borrowed from onshore wind farms, and incorporating technology from the oil and gas industries, while adapting it to the specific requirements of wind turbines.


Existing shallow water designs

The designs currently used in shallow water include monopiles and gravity base foundations, while a suction bucket concept is in the later stages of development.

Monopiles are used in the majority of offshore wind farms. The London Array project, which is currently under construction, is set to become the worlds largest offshore wind farm with 177 turbines producing 1000MW supported by monopiles. They are relatively simple by design and have a minimal impact on the seabed; but they are limited by resonance in deeper water. The frequency of the turbine decreases as water deepens. To maintain stiffness the diameter of the monopile must increase; eventually to the point where it far exceeds the necessary size for structural support. The greatest practical depth for a monopile is considered to be around 30 metres.

Gravity base foundations are an alternative and have been used on several sites, including the Thornton Bank project in Belgium. They require in depth seabed analysis as they are sensitive to soil conditions, but do provide an option where pile-driving is not viable.

Suction buckets are not in commercial use as yet, but significant research has been carried out on them. They consist of a wide base that is driven into the seabed by drawing a vacuum and using hydrostatic pressure to seat the bucket. This technology offers an alternative to monopiles and the use of large pile-drivers.

Norwegian company Seatower introduced a crane-free gravity base foundation late in 2010 that is economically viable at depths of up to 50 metres. In an interview with WindEnergyUpdate CEO Petter Karal said, “The crane-free gravity is economical down to about 50 metres water depth. However, we have ways to build cost-efficiently down to as much as 100 metres based on crane-free technology.”

The foundations can be fully manufactured at quayside, before being towed out to sea using standard tugs. There is no need to use specialist vessels or cranes during installation, and the entire installation process takes just 12 hours, which means less downtime due to bad weather conditions. Although these foundations are not yet in use commercially the technology has been proven in the oil and gas fields, and as there is no seabed preparation required there is less impact on the environment and local eco-system.

This technology could provide an economically viable solution for deep water installations due to the low manufacturing and installation costs.

Transitional water concepts

Source: NREL

Transitional foundations are used, and are being developed for water depths between 30-60 metres. As water depth goes beyond 30 metres larger substructures with wider bases are required to cope with increased overturning forces, and to meet design specifications for stiffness. Some of the examples in the image above are not yet in operational use, and due to financial constraints surrounding installation, may not prove to be competitive with shallow water wind farms.

The guyed steel tube design has yet to be tested in the water, but offers a wide support base. The Spaceframe concept is derived from land based designs, although they were not used extensively onshore due to high costs.

The Talisman, or ‘jacket’, design was first used by Talisman energy in 2006 at the Beatrice Wind Farm Project; with two turbines installed on the lattice like structures at depths of 45 metres.

The design was also used, along with a tripod foundation at the Alpha Ventus Project, north of the island of Borkum, Germany. Completed in 2009 the project incorporated six jacket type foundations alongside six tripod foundations. All twelve turbines are 5 megawatts, and it is the largest transitional wind farm in the world today.

Learn more about about deep water designs here.

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