Atmosphere to Electrons (A2e) is a multi-year, U.S. Department of Energy research initiative with the goal of reducing wind-power project costs through an improved, physics-based understanding of the wind plant operating environment through advanced modeling and simulation capability.
According to the research initiative, better insight into flow physics has the potential to reduce energy losses by up to 20% at a wind farm, lower project operating costs, and improve project financing terms to more closely resemble traditional capital projects.
At a recent AWEA Wind Resource Seminar, National Renewable Energy Laboratory’s Senior R&D Engineer Jason Fields discussed the A2e research goals in light of the ongoing industry changes. This was part of a session that focused on the future of wind power and wind-resource assessment over the next five to ten years.
Fields began by asking the audience to imagine the next generation of “smart wind turbines” and to consider how the industry might design them. It’s not difficult to envision taller turbines with longer, more aerodynamic blades, and improved controls that seamlessly capture more wind while integrating power into the grid. For Fields, however, the answer is mainly found outside a single turbine.
“We think the answers lie in a few different areas, but fundamentally in a better understanding of the atmosphere,” he said. Fields maintained that significant challenges still exist that relate to fully understanding a turbine’s response to the wind flow in and around wind plants.
“We need a model that represents the full structure of the atmosphere at many different scales and that includes wake modeling, control of the complete wind plant –not just individual turbines – and a better understanding of wind-plant performance uncertainty.”
To help get there, A2E is a seven-year (2014 to 2021), multi-partner collaboration that has six main focus areas:
- Performance risk, uncertainty, and finance (how uncertainty in wind energy is represented financially),
- High-fidelity modeling (includes simulations, high-performance computing and validation measurements),
- Data archive and portal (ensuring a secure place to store and access relevant data),
- Integrated wind-plant control (a look at the total wind plant and not just individual turbine control),
- Aeroacoustics and propagation (a look at noise generation)
- Integrated system and design analysis (finding the best designs for full wind-plant control).
“We’re essentially trying to tie in all these disciplines into a single package that accurately represents and measures an entire wind farm,” said Fields. However, one challenge in doing so is keeping up with today’s push for growth and technology evolution, which lends to ongoing design and manufacturing changes.
“Technology is evolving at a rapid pace. We’re moving toward an ability to modularly deliver wind plants with multiple rotors, multiple hub heights, and multiple nacelle-nameplate capacities in the same project,” explained Fields. “So, we need measurement and modeling tools that adapt to these new manufacturing capabilities.”
As an example, Fields displayed the Wind Plant Scales graph from the Department of Energy’s 2014 Wind Technologies Market Report. The black line shows the average rotor diameter over time and the bars are histograms of the average rotor size by project.
“This graph serves as one example of those changes. Before 2009, there were virtually no projects with rotors larger than 100 meters,” Fields pointed out. “But now that figure represents 80% of the market. Wind plants are also increasing in size.”
The trend toward larger wind farms likely won’t change anytime soon. According to Fields, if wind manufacturers have the ability to deliver varying components, brands, and sizes for the same project, it reshapes the traditional wind-farm design landscape. It also begs an important question. “We have a clear theme for the future: larger rotors, larger plants, higher hub heights. So we have to ask the question, ‘Are point measurements sufficient to describe the atmosphere at a wind farm – and to the level of detail necessary – to accurately predict loads, predict power, and predict the total resources across the site?’”
This change in landscape and turbine size, ultimately, has to drive advances in wind measurements and the science behind those measurements. One area of interest to Fields is in wind-plant optimization. This means effectively increasing power generation, but to do so it’s necessary to start with highly accurate data. “For plant optimization to make any sense, we need to ensure we’re relying on high-accuracy inputs and wind-flow data,” he said.
This drives additional reliance on remote-sensing devices along with accurate wind-flow and wake models. It also means models will need to incorporate full wind-plant control data for accurate energy estimations. “The future of wind-plant control doesn’t look at how turbines operate individually, but rather as a collective to maximize generation of an entire wind farm.”
To provide an example, Fields showed a video that demonstrated the negative wind-flow effect that upstream wind turbines can have on downstream units, leading to sub-optimal plant performance. One solution is to integrate an optimized yaw-based wind-farm control system, which can “steer” wakes from greater overall power production.
For an optimized wind-plant approach to work effectively, the underlying inputs must be accurate. “Right now we have successfully demonstrated those individual turbine control capabilities, but if we’re looking at total wind-plant control, that changes the game, so our tools must adapt to this change. That is what we’re working on, an advanced wind-plant optimization approach based on highly accurate wind-flow data and full wind-plant controls.”
Other changes to consider for the future of the wind industry include energy storage. “The ability to arbitrage energy and sell it at different times can mitigate some of the variable supply challenges we have. This has implications for transmission systems, wholesale prices, retails prices and consumer choice,” he concluded.
The ultimate goal of A2e is to ensure future plants are sited, built, and operated in a way that produces the most cost-effective electrons. A2e researchers certainly have their work cut out for them to keep up with demand and the changes in the industry. “Ultimately, there’s significant room for improvement in understanding wind flow, optimizing wind design, wind-plant controls, and storing energy, and this is shaping the R&D work we do for the future of wind-power production,” said Fields.