#3DwindMaps -The world’s largest trial of scanning Light Detection and Ranging (LiDAR) technology by Carbon Trust is taking place on Dublin Bay. This is the latest Offshore Wind Accelerator (OWA) project designed to help reduce the cost of energy from offshore wind.

Over the next three months the most comprehensive test of scanning LIDAR technology will take place, where four different scanning LiDAR systems will be put through their paces, alongside three vertical profiling LiDARs for validation purposes. The project is being supported by independent renewable energy company, RES and maritime safety organisation, Commissioners of Irish Lights.

Accurate wind resource measurements are critical to wind farm development because they are used to calculate the potential energy yield from a wind farm, which dictates the terms of the project financing. This can be a significant proportion of the overall project cost, accounting for around 45 percent for an average wind farm.

Scanning LiDAR is not a new technology. Conventionally, it is used by the defence and aerospace industries to monitor for oncoming weather fronts. But it does not have a proven track record in offshore wind.

Normally wind resource is measured using large steel towers called met masts, which require a large capital investment (£10-£12m) incurred at risk before a project gets the go ahead adding significant upfront costs, which could inhibit the exploration of new sites. The OWA project aims to test how accurately scanning LiDAR technology can measure wind resource for potential wind farm sites, which could deliver significant cost savings in the early stages of wind farm development.

The OWA has been working for the past few years to support more cost effective solutions, focusing on the development and commercialisation of a number of floating LiDAR systems, to significantly reduce upfront capital expenditure. Yet measurements taken by both masts and floating LiDAR are limited in that they only provide a measurement of the wind resource at a single point in space. For an offshore wind farm covering an area of up to 200 square kilometres, this can create uncertainty on the wind speed at locations far from the measurement point. This is known as spatial variation, where measurements may not representative of the entire site. This is translated into risk incurring additional financing costs to wind farm development.

Scanning LiDAR technology has the potential to reduce the risk associated with spatial variation. These systems are capable of scanning with a usable range of between 10 to 30 kilometres, to impressive levels of detail, taking over 100 measurements per minute. This allows developers to build a much more detailed picture of a site, not only significantly reducing uncertainty of spatial variation, but also allowing developers to better plan the layouts of the turbines to best exploit the individual wind conditions at the site. Increasing confidence on spatial variation could reduce risk to minimal levels, which can save millions of pounds on a project and reduce the cost of energy from offshore wind.

A difference of only 0.2 mph in wind speed can result in significant variation of yield calculations over the lifetime of a wind farm. It is therefore critical that the industry has confidence in scanning LiDAR devices being sensitive enough to detect such small variations. The OWA trial aims to test the sensitivity of the devices to picking up these variations in wind resource.