Analyses of model for wind resource assessments in coastal Ghana

The global demand for renewable energy has risen steadily the past decade. Wind energy has become one of the three major renewable energy resources that is exploited on a large scale for global power generation. As of 2018, global installations of wind power stood at 591 GW, having quadrupled in the past decade.

Condition dependent

“Extractable wind energy depends on wind characteristics such as its speed, density, and prevailing directions,” PhD candidate Denis Edem Kwame Dzebre says.
“These conditions important roles in several aspects of wind energy exploitation, such as the prediction of the economic viability of projects.”

Pre-feasibility studies

When evaluating areas for potential wind energy development, pre-feasibility studies play a crucial role in the assessment process. These include the performing of large area screening of possible wind power project sites, designing of effective mast measurement campaigns and feasibility assessments of projects.

Lack of information

Electricity supply challenges in Ghana have stemmed from several factors over the years. These include over-dependence on electricity from thermal and hydro sources. Several studies have reported the feasibility of large-scale generation of electricity from wind in Ghana.
Though studies have suggested that wind projects are feasible in this region, development of
the resource still suffers from several challenges.
“One of these are inadequate data for resource assessments,” Dzebre explains.

Downscaled datasets

A source of data for such assessments that has increasingly become popular over the years, is downscaled meteorological datasets which are sometimes produced with Numerical Weather Prediction (NWP) models. Owing to diverse model physics and dynamics options, as well as the fact that wind conditions vary with geographic location, model-validation studies are necessary towards the use of the model for a location.
“Because of the uncertainties that come with wind flow modelling, the validation of NWP models is an important step towards their application for wind data downscaling for a geographic location,” Dzebre says.

Models for wind prediction

In his doctorate, Dzebre has examined the application-oriented use of the Mesoscale Weather Research and Forecasting (WRF) model for wind prediction applications in the coast of Ghana and neighboring countries in the West African sub-region.
He has also aimed to fill in previously identified knowledge gaps in international literature.

Model results comply with standards

Dzebre’s results of a simulation covering a year with a model configuration showed that the MWP model is capable of downscaling wind data with error metrics that can meet most of the performance benchmarks that have been reported in literature.
“My results also suggest that the configuration established from the studies is probably suitable for offshore assessments in the area, but that will require further verification,” he comments.

Continuous validation important

One of Dzebre’s key conclusions is that, continuous validation of model configurations is important for determining optimal configurations of the model.
“Also, in future wind validation studies, the often-used practice of selecting ‘closely-associated’ Surface Layer - SL - physics schemes for Planetary Boundary Layer - PBL - physics schemes should be discouraged.”
In addition, possible interactions between options need to be carefully investigated in these studies.

Reduce chances of misleading conclusions

“Future studies should employ decision-making criteria that seek to reduce the chances of drawing misleading conclusions.”
The criteria of consistency in exhibiting relatively good performance with multiple validation criteria is used in his thesis.

Better assessments

The optimized model will be helpful in the planning stage of projects.
“It should make it cheaper and easier to assess sites for wind power plants along the coast of Ghana, and some countries in West Africa,” he concludes.

Denis Edem Kwame Dzebre defends defend his PhD thesis “Sensitivity Analyses of the Weather Research and Forecasting Model for Wind Resource Assessment in Coastal Ghana”, on 18 December 2019.

Published 12. December 2019 - 10:54 - Updated 12. December 2019 - 10:56