Maximising the profitability of wind power

Published:  07 February, 2014

The need to reduce the ‘Levelised Cost of Energy (LCoE)’ is focusing many minds within the wind power industry on how offshore costs can be driven down by technology and within the supply chain. One undeniable truth is that the availability of turbines is crucial to profitability, and efficient vibration monitoring solutions are key to achieving that, says Chris Hansford*.

According to the Wind Energy Update website, over 22 GW of offshore wind power has already been consented for future development in Europe. The site says that the success of these projects will depend on one immediate factor, the lowering of the LCoE (Levelised Cost of Energy: the price at which electricity must be generated from a specific source to break even over the lifetime of the project).

Lowering LCoE means addressing a series of issues. It means setting in place a series of procedures that will increase efficiency, enabling operators to minimise maintenance costs and maximise turbine availability, protecting profits for operators and providing the rest of us with a supply of renewable, reliable energy. To achieve this, the industry is focussing its energies on sharing knowledge, building relationships between operators and OEMs, and generally strengthening its planning and thinking to focus on the long term. For example, the Offshore Wind Construction, Installation and Commissioning Conference was organised with the aim of uniting the construction niche of the offshore wind industry. Conferences such as this aim to provide answers to the crucial business strategy and technology questions and help advance offshore wind industry in a rapidly evolving market.

The agenda at Offshore Wind Construction confirmed that defining pathways to a reduced Levelised Cost of Energy (LCoE) is a key concern, with much thought invested in ways in which offshore wind costs can be driven down by technology and within the supply chain. These include developments in offshore wind foundation design, cable installation technology and fabrication facility developments to ensure CAPEX reductions. They also include how to implement a Coordinated Installation Logistics Strategy by assessing new tools and processes for the most cost-effective transport of major components from the productions facility to the quayside and the construction site. And, of course, the debates look at the benefits of partnerships, alliances and contract structures to explore how operators from across the pan European offshore wind value chain can reduce costs and minimise risk.

This last point is crucial to long term efficiency and profitability. Minimising risk is an exceptionally valuable capability, and an essential part of any preventative maintenance programme for wind turbines is the application of vibration monitoring technology. The rotating parts of wind turbine generators need to be continuously monitored to warn of bearing and component wear. And since wind turbines are frequently installed in remote locations with high costs incurred when there are any failures, it is vital to be able to determine potential problems before they occur so remedial action can be taken. The cost of wind turbine maintenance is high, even when it is onshore, and for example, if a crane is required in a remote location, it can be a logistical nightmare as well as a huge expense. However, by successfully implementing an effective condition monitoring strategy, engineers will prolong equipment life and minimise maintenance and downtime costs.

Many thousands of vibration sensors, or accelerometers, are sold worldwide to wind turbine operators. There are two main categories: AC accelerometers, which are used with a data collector for monitoring the condition of higher value assets such as wind turbines, and 4-20mA accelerometers, which are used with a PLC to measure lower value assets such as fans and pumps. However, there are many variations within these categories that have been engineered to meet specific needs.

For example, low frequency accelerometers have proved to be an excellent solution when it comes to monitoring tower movement. These accelerometers, dependent on the customer requirements, have been either all 100mV/g or the higher sensitivity specification 250 or 500mV/g components. They are used for monitoring the low speed aspects of the generator, for example, output shafts. Most contracts for these accelerometers have involved supplying a local junction box (HS-JE), which accommodates the accelerometer cabling at the top of the wind turbine. Dependant on the exact configuration, multi-core is connected and fed back down to ground level for termination into the online monitoring system. Online programmes enable operators to monitor turbine conditions in real time using any computer or handheld device with Internet access. Using this information, the condition monitoring system can then provide an accurate performance overview that will identify faults and predict failures before they occur. This then allows operators to develop an effective predictive maintenance strategy, which can ultimately allow considerable savings in time, resources and money to be realised.

In applications where it has been difficult to justify the expenditure of a full on-line system, some wind farms have applied a lower cost option using fixed sensors mounted as previously described, with a local junction box and multi-core connected to a switchbox on the ground. They then have either a local contract vibration analysis company to take readings or, alternatively, the wind farm owner employs a vibration analysis team to take regular readings. The latter method, which is selected when budgets are tight, is limited in its effectiveness since the data is only as good as the last reading that was taken. However, this is still a useful means of applying preventative maintenance and it is worth considering that if and when a bigger budget becomes available this can be expanded into an on-line system by replacing the switch box with a monitoring station that is capable of providing in-depth vibration analysis using FFT (Fast Fourier Transform) with remote web access. In selecting the best solution for the available budget, expert providers can apply their knowledge of vibration monitoring to the application, working closely with the customer to provide an appropriate technical solution at a cost-effective price.

Thanks to the latest vibration monitoring solutions, wind farm manufacturers and operators are now able to increase the performance and reliability of their turbines and lower LCoE. With each prevented fault, the value of the savings achieved runs into hundreds of thousands of pounds, and what would have been costly downtime becomes profitable uptime. Whatever the blend of solutions established to maximise the profitability of wind power, the availability of turbines is crucial and efficient vibration monitoring solutions are key to achieving that.

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*Chris Hansford is managing director of Hansford Sensors.

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