Double award for wind energy prediction
How do forests affect the potential wind energy resource?
A first year PhD Student from CREST has been awarded a prize for best presentation by the Wind Engineering Society. Cian Desmond was invited to speak by Dr John Owen of the University of Nottingham on the basis of a research poster at the recent International Conference on Wind Engineering in the Netherlands.
He followed this success up with a second win for best presentation, this time at the Midlands Energy Graduate School (MEGS) Christmas Event and Inaugural Lecture, 13th December 2011, Loughborough, where he gave his presentation a seasonal flavour with the title 'Wind Farms and Christmas Trees'.
Wind farm developments are being considered in increasingly complex terrain where the wind’s behaviour is more difficult to predict and Cian is looking at the effect of forests on the wind energy resource. The energy available in the wind is proportional to the cube of the wind speed, so highly accurate flow models are required in order to reduce uncertainty and thus the cost of finance. It is also important to understand the turbulence generated in such complex sites, as this has implications for the design of wind turbine components.
In recent years, full CFD solvers have become a frequently used tool for resource assessment in sites where trees are present. The current state of the art requires that CFD models of such terrain be tuned in order to match field data. The parameter most often tuned is the leaf area density profile (LAD) which describes the structure of the canopy.
 |
 |
|
The LAD profile derived from a set of high defintion images. |
One of the architectural tree models in place in the wind tunnel. |
Cian’s research is exploring a novel method of acquiring a realistic LAD for wind tunnel canopy experiments by using a realistic model trees and photographic analysis software. Early results indicate that his method reduces the required model tuning and thus decreases uncertainty.
“I’m building on work that has been done at CREST over the past four years by Scott Wylie and others,” Cian explains. “The aim is to increase the predictability of wind energy. We are placing small model trees in wind tunnels, measuring the resulting wake and then replicating these experiment in CFD, which is essentially a wind tunnel in a computer."
A series of experiments extending this work will take place in Surrey University and Orléans University over the coming months. The work at Surrey will study the effect of thermal stability by varying the temperature in the tunnel at different heights to simulate realistic atmospheric conditions.
“This is exciting!” Cian continues, “Surrey has one of only seven wind tunnels in the world that can achieve this effect and the only one in Europe. If successful these experiments will make a significant contribution towards understanding how forest effect the wind energy resource.”