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A WiSE renewables choice

Juhl Energy is building a wind-solar hybrid project in Minnesota that marks the commercial launch of GE's WiSE (Wind Integrated Solar Energy) technology, which can transform projects previously considered marginal into projects that may get the green ligh

By Tony Kryzanowski

A new hybrid system called Wind Integrated Solar Energy (WiSE) from GE Renewable Energy channels power production from both wind and solar generation sources located on the same land base through the wind turbine converter and eliminates the need for a solar power inverter.

And Minnesota-based Juhl Ener-gy is building the first commercial solar-wind hybrid project using GE Renewable Energy's WiSE technology in the United States. The combined 4.6-megawatt (MW) Red Lake Falls project is located near the hometown of Juhl Energy founder and CEO Dan Juhl.

The $10 million project consists of two 2.3-116 wind turbines from GE Renewable Energy's Onshore Wind business and 1 MW of solar power conversion equipment provided by GE's Current business. Project construction is expected to be completed by the end of the year.

"Any new greenfield development could easily use the WiSE system and combine solar and wind," says Juhl. He added that one of the benefits of the system is the potential to produce more higher-value, on-peak energy for regions like Minnesota, where wind and solar produce more power at different times of the day.

The hybrid approach of wedding solar and wind is not new. There are essentially three approaches. One is to build two stand-alone wind and solar installations that share the same land base, with each having their own infrastructure, substations, and interconnection points. The second approach is the development of two systems on the same land base that may link up just after the wind turbine, sharing the same substation and interconnection point. The third and newest approach is what can be described as turbine-integrated, where wind and solar infrastructure channel energy through a single converter on the wind turbine while eliminating the need for a solar inverter. This is the WiSE approach, although it is not the only system of this type available.

GE's WiSE hybrid technology—and other systems like it—have all the hallmarks of a potentially extensive impact on the entire renewable energy sector, in an age when renewable power developers are searching for new ways to tap into regions that are less attractive for stand-alone wind or solar resources.

The ability to integrate both these intermittent sources of renewable power production through one converter while eliminating the solar power inverter significantly reduces capital and maintenance costs, thus putting less attractive development targets back on the radar.

Steve Bravo, production manager for Onshore Wind at GE Renewable Energy, says that implementation of WiSE could deliver savings of 10 to 15 percent in capital costs and 25 to 30 percent in operations and maintenance costs.

"If we can take 10 to 15 percent out of a combined project's cost, that's a pretty big push to allow for projects to happen in places that they didn't happen before," says Bravo.

He adds that what's contributing to the positive business case for deploying the WiSE system is how capital costs for both wind and solar power infrastructure continue to decrease, with solar in particular closing the capital cost gap with wind.

The Red Lake Falls project, located in the upper U.S. Midwest, is an example where, three years ago, few would have considered it a good location for renewable investment. However, with capital costs decreasing dramatically, and with availability of a hybrid option like WiSE, it has become viable for renewable development, as proven by Juhl Energy's investment in the area.

"You are combining two renewable resources that are declining in cost to begin with, and the overall package is still 10 to 15 percent cheaper," Bravo says. "So, the breakthrough is that it makes renewable a much more attractive option for people."

In theory, deploying hybrid technology like the WiSE system could significantly accelerate how quickly renewable energy production captures market share from power now generated from non-renewable sources, if it provides a new tool for developers to consider investment in areas where just a wind or solar installation doesn't make financial sense.

Bravo cautions, however, that it is still early in the advancement of hybrid renewable power development to really put solid savings numbers together, which is why development of the Juhl Energy Red Lake Falls project is so important as a commercial proving ground. It is considered GE Renewable Energy's commercial launch of its WiSE technology, and although this is a smaller project, Bravo says that the approach and technology can be deployed on any size project.

The GE Renewable Energy WiSE system includes the company's control logic technology, and Bravo says this is a critical part of the overall system. It gives priority to power produced by either resource, thus creating the potential for more stable power production at or near the nameplate capacity of each wind tower converter, even in situations of low wind speeds.

 
  

Juhl, who has championed and encouraged the development of this concept of a combined wind-solar hybrid renewable power system with GE for some time, says what fueled his interest in this type of system was his observation of weather conditions at his home in Minnesota. He noticed that the wind resource was considerably higher in winter and the solar resource considerably higher in summer. It was a simple case of fewer or more low pressure systems to drive the wind turbines, depending on the time of the year. Also, the hybrid approach provides more stable output over 24 hours, with solar obviously more productive during the day and wind at night. So the concept of a hybrid wind-solar project seemed like a natural fit for Juhl's area, which is why he is pleased that the Red Lake Falls project was chosen by GE Renewable Energy for the first commercial implementation of their WiSE technology. Bravo says that Juhl has been a great partner in GE's development of this technology.

Implementing the WiSE system by integrating solar power production through the wind turbine's converters is expected to increase system capacity on the Red Lake Falls project by between three to four percent and increase annual production by 10 percent.

Juhl says that typically when both wind and solar are part of the same project, they each take up considerable real estate. But when wind and solar are combined using the WiSE approach, there is a much smaller footprint. The entire Red Lake Falls project is on seven acres, consisting of two acres for the wind turbines and five acres for the solar panels.

"If you were to try to achieve the same power output with solar alone, you'd probably take 120 acres of land, and it would probably cost $30 million," says Juhl.

The solar arrays dedicated to each wind tower are within 300 to 500 feet from the tower. To maximize the wind turbine converter output, he says studies show that for every 2-MW tower, having the ability to generate 500 kilowatts of solar maintains near maximum throughput on each wind turbine converter. GE is supplying all the wind turbine and solar hardware on this project.

Working with them are Minnesta-based companies: electrical contractor Premise Inc., based in Minneapolis, and Moorhead-based Ironhorse Crane and Hotshot Service, which is providing the crane, foundation, and tower erection services.

Bravo says the challenge with the WiSE approach is to ensure that the correct control logic is deployed with this hybrid system so that both the wind and solar infrastructure can communicate, and the entire system will react in the most efficient and beneficial way for the customer, placing more of a priority on the wind or solar power depending on local available resources and the customer's needs.

The capital cost savings with this system come from sharing the converter, the pad-mounted transformer, cabling, switchgear, and substation and avoiding the inverter on the solar arrays. Other capital cost savings include using the same interconnect and being able to use the same interconnection study during the design phase for both the wind and solar elements.

On the operational side, it is simply a case of being able to use the same crew to conduct operations and maintenance for both the wind and solar components, while also avoiding inverter maintenance.

"But it's not just the electrical tie-ins to the converter, it is also the software and controls needed to balance and control that production," says Bravo.

While not the only player in the turbine-integrated renewable power market, GE has been a leader in its development—this is not the first application of this technology. Back in 2013, GE deployed this hybrid technology on a commercial scale in a wind-storage combination on the Goldthwaite wind farm in Texas. GE took that knowledge and developed the WiSE wind-solar hybrid solution. In addition to greenfield projects, GE is scoping out if and how this WiSE technology could also potentially be deployed on existing standalone wind and solar farms to boost efficiency and provide more stable production.

Juhl says there has been tremendous support from the Red Lake Falls community for this renewable project. The biggest challenge he has faced is negotiating a 20-year power purchase agreement with the local utility, Otter Tail Power Company. He is looking forward to working with other smaller utilities like rural and community-based cooperatives to demonstrate to them that this wind and solar hybrid approach is a financially viable option for them as well, given the capital cost savings and the higher efficiency and more stable output the system offers in regions where renewable development previously did not make financial sense.

 


September/October 2017