Developing industrial-scale wind farms requires significant upfront capital to assess the wind resource of a given site. The ability to obtain financing and develop a project directly depends on quality wind data to predict the revenue from the wind farm. A new meteorological tower on the market is lowering the barriers of entry for industrial-scale wind developers, as it gathers high-quality data for a lower upfront investment.
Capital City Renewables (CCR) successfully installed a 100-meter aluminum lattice meteorological tower in Colorado. This is the second 100-meter meteorological tower of its kind in North America – one that can be climbed and easily moved by tilting it down. When a tower can be climbed, anemometers and wind vanes used for measuring wind data can be easily replaced at a much lower cost. The ability to move a tower to a new location enables developers to make better use of their assets, instead of disposing of a tower after one use.
The revenue from a wind farm is dependent on the energy production of the project. A recent trend in the wind industry is to boost wind data accuracy in the preliminary stages of a project to reduce uncertainties in wind speed measurements at hub height (the height of the turbine from the ground, not counting the blades) and associated financial risks while financing and constructing the wind farm.
“The reason why you want to measure at hub height is because wind changes with height,” explains Katy Briggs, senior engineer at DNV Kema. “There are certain assumptions we can make to estimate wind speeds at heights above measurement height, but there can be errors in that. The more you can measure at hub height and across the turbine rotor, the better estimate you can make.”
There is demand for wind data from higher elevations, closer to the hub height of the wind turbine that might be sited in a given location. Instrument reliability is paramount, but placing instruments at greater heights, where they are exposed to stronger winds and a higher risk of lightning damage, increases the likelihood that instruments will need to be repaired or replaced.
“Most hub-height met towers installed for the wind industry are actually steel communication towers that have been adapted slightly,” explains Kiril Lozanov, CEO of CCR. “Moving these heavy towers is costly and difficult, especially if the tower is mounted on a cement base with cement anchors. The met tower that we installed is special because it is designed to meet the unique needs of the wind industry and provides everything needed at a much lower cost.”
Lozanov estimates that hub-height steel lattice towers can cost developers between $160,000 and $200,000 to install and maintain the tower with the necessary equipment and instruments and remove the tower for future use. The new technology that Lozanov is using costs between $120,00 and $130,000 to for the same services. While a steel lattice tower requires a cement base, the aluminum lattice tower can be mounted a steel plate because the tower is not as heavy. The steel plate can be reused for future projects and the installations and decommissioning costs are lower because aluminum weighs less than steel, thus there is a lower sunk cost associated with installing an aluminum lattice tower.
“If you’re developing a project, there are risks that the project won’t go through due to market changes, environment permitting, low wind resource, or a variety of other reasons,” says Briggs. “So there is a balancing act of not investing too much before it’s a sure thing, but investing enough to properly assess the value of the project. Part of this balancing act is the investment you make in towers and other measurement equipment. Having mobile towers or remote sensing devices can allow you to recoup some of your investment if a project falls through, by reusing your equipment at another project.” She also points out that not all the equipment from a tower can be reused, and that there are still costs associated with decommissioning, shipping and reinstalling the tower.
“It seems the industry is pushing to build turbines that are taller and taller,” Jim Fietzer, safety operations manager for CCR. “I think the use of this aluminum lattice tower mounted on a steel plate puts our clients in an advantageous position in the future. If the developer decides to push for 120-meter turbines on their next project, they can simply add another 20 meters to their monitoring tower and use it again.”