Going with the wind

"We like to be close to the bleeding edge of technology and this technology allows us to showcase New Zealand research capital on the international stage." So says Blair Walter of multinational engineering consultants Connell Wagner. He's talking about the intellectual property and associated modelling tools his firm licensed from the University of Canterbury's Canterprise in July 2006 and which has since been developed further. This technology allows Connell Wagner's clients to prospect for the best sites for windfarms across New Zealand and now they are selling their services overseas as well. Previously, those looking for windfarm sites had to put up a mast to collect wind data about a specific location and it took six to twelve months to collect sufficient information. Much more time was needed to optimise the actual position of each turbine within a farm. But with the University of Canterbury-sourced technology it takes just a few weeks to evaluate many potential sites in an area. Blair calls it "meso-scale meteorological modelling". That means it models a region of 50 to 100 square kilometres at a time.

But working with windfarm sites was not on the agenda when Professor Andy Sturman of the Department of Geography at the University of Canterbury applied to the Marsden Fund back in 1997 for funding for a research project to study the effects of complex terrain on local winds. The focus of this very basic research was on understanding the processes affecting airflow, including the effects of lake breezes, sea breezes and winds generated by the varying nature of the terrain (mountain, valley and slope winds) – native or pine forest, tussock, bare rock, ice, snow, water, etc. It was a novel approach combining both measurement and modelling techniques. Remote sensing and GIS (geographic information systems) were applied to the modelling of the thermal influence of the terrain on the overlying atmospheric boundary layer in mountainous regions.

The particular location chosen for the study was in the MacKenzie Basin in Canterbury, where strong cool easterly breezes often penetrate into the mountains in the afternoon, frustrating glider pilots who like to use the convective lift created by surface heating in the area. These strong easterlies were thought to be sea breezes originating at the coast –at least until the Marsden Fund research proved this perception to be basically wrong.

It was shown from the research that the effect of sea breezes on local airflow in the basin is very small. Air moves inland from the coast to the mountain basins as a result of the heating of the elevated land mass, effectively producing a sucking effect, drawing in cold air from either side, but particularly the east. This discovery, that the elevated mountain land mass was significant in generating this strong daily cycle in the wind during summer, had not been identified previously. This is also bad luck for glider pilots who are seeking to avoid cold air in-rushes because of their effect in cutting off convective cells of rising air.

The ground surface characteristics – tussock, pine, forest, snow, ice and so on – also turned out to be significant factors in generating local winds. For example, Lake Tekapo was considered too small to be able to generate or modify airflow, and yet both measurements and models showed that this was not so.

The results quickly generated interest from wide sections of the community. There were new implications for aviation, such as predicting turbulence in mountainous terrain – especially its frequency and severity – and horticulture, such as temperature mapping and frost prediction in areas of complex terrain. There was interest too, from those starting to contemplate the use of wind to generate electricity. They wanted to know if there was enough wind, but also if turbulence would be sufficiently severe to cause blade fatigue. It was very early days for electricity generation from wind. In addition, there was interest from those charged with reducing and monitoring air pollution and the effect of wind on forest fires.

The research team hadn't anticipated the huge amount of consulting work from their original Marsden Fund project. Clients now include most of New Zealand's electricity generators, regional councils, and environmental consulting companies. Teresa Aberkane, Senior Air Quality Officer at Environment Canterbury relates how her organisation was one of the first to benefit from the results of the team under Professor Sturman. "We've been working with Andy and his team since the mid 1990s on air pollution around Christchurch" she recalls "and we've come a long way. Our job here is often beyond our own capabilities and we rely on the University of Canterbury team to investigate further using our monitoring and emissions data". For example, Aberkane was wanting to know if emissions in the industrial area to the south of Rangiora, a town to the north of Christchurch, had an impact on Rangiora itself. Placement of monitoring equipment is another important issue. Some modelling work was used to show where the worst ozone concentrations were likely to occur in Canterbury to help identify where to monitor. "We can only monitor in one or two locations in a town" she says "but are they the right ones? Andy Sturman's team, including his students, have become the experts in providing us with the answers, and we enjoy this very critical relationship."

Following completion of that first Marsden Fund project, two FRST projects worth over $1 million have been awarded to the researchers under Professor Sturman and this research has enhanced the knowledge and skills, especially in understanding the dispersion of air pollution emissions.

But more recently, electricity generation by wind farms has burgeoned in New Zealand as we race to become much more sustainable in our energy use here. The research group was greatly expanded with full-time employees involved in this work becoming part of the Connell Wagner team. Identifying the best wind sites and doing it reliably without the normal 12 months time to study a site to ensure it is workable is a big saving to the industry and the country. The benefits from the research are not just in the jobs created in the research group and the activity at Connell Wagner both in New Zealand and overseas. They include the benefit to the whole New Zealand wind generating industry, and benefit to all of us in the country from our use of reduced amounts of fossil fuels for electricity generation. Getting our wind farms going more reliably and more efficiently than before is also significant and worth many millions each year they are operating. It's also about investment in graduate students – two PhDs and several Masters students from that first Marsden Fund project are now out and about. There's one using the skills in the wine growing areas of Marlborough and Nelson, identifying the best frost-free locations for growing grapes. Two books have been published and there have been over 50 other refereed publications relating to the research work. Numerous collaborations have resulted from the original research, including with Universities in Canada, Germany, USA and Australia, as well as other universities in New Zealand.

Where does this work take us from here? It's hard to predict really. But for Connell Wagner it's opened up a whole new field for them. Different clients use this technology in different ways. For some it's for prospecting for new wind farm sites, while for others it's for developing the sites to optimise the wind use, including locating each turbine. For Professor Sturman's group the new opportunities now open to them include applying the technology to unanswered questions in a much heralded field – global warming. Key issues such as the heat exchange processes between the earth’s surface, the overlying atmosphere and their significance for multi-scale interactions within the atmosphere need to be answered. He has recently been invited to collaborate with Australian partners to measure and model the heat exchange processes over coral reefs, to assess its impact on coral well-being. These are all new areas which were not so significant and certainly not foreseen when that original application was submitted to the Marsden Fund. Maybe one day glider pilots too, will benefit from the research.