International renewable-energy consultancy Natural Power says it has placed a no-cost-to-use, on the Web to estimate wind-flow complexity on potential wind farm sites. As potential development sites with, flat terrain become fewer, more projects are built in or near forests and on complex terrain. These complex-flow sites are often associated with harsh wind conditions likely to affect turbine performance. For example, complex terrain can induce wind turbulence and high loads on turbine blades.
As a result, increasing concerns arise about under-performing wind farms. Maintenance costs are higher than expected, performance is lower, and warranty claims are more common. Tools for designing efficient wind farms in complex terrain are available but there is less awareness of them within the industry. For example, CFD (Computational Fluid Dynamics) modeling, lidar measurements and well-planned measurement campaigns can help optimize wind turbine locations and provide manufacturers and investors the information they need to properly assess the site condition.
Whether to use such advanced tools rather than standard software is not always obvious. Although the use of RIX (Ruggedness Index) values help assess complex terrain, it is not always readily available to investors or developers, and does not take in to account the effect of land cover on flow complexity. In response, Natural Power has developed a complexity assessment applet available gratis on the company’s website. For an estimation of flow complexity, the applet requires turbine locations, which can be uploaded as Google earth place marks, and a simple estimation of forest coverage in the area of interest. The website then computes a complexity index, taking into account topographic features and approximate land cover. Results can be visualised in a report that summarises findings, recommendations, and next steps for development.
‘‘The complex site applet should help minimise the risk of underperforming wind farms by providing owners, investors, and wind specialists with an easily accessible estimation of risk at early project stage and thereby informing about the need for tools and methods appropriate for the site conditions,” says Director of Natural Power France Oisin Brady. “Our team can then suggest the best possible options for site development– from further CFD calculations which we perform with VENTOS, or a prescribed wind measurement campaign with traditional techniques such as met masts or more advanced assessment tools such as our ZephIR 300 lidar.’’