TODAY’S STUDY: The Emerging Global Vision For Wind
Results of IEA Wind TCP Workshop on a Grand Vision for Wind Energy Technology
April 2019 (International Energy Agency via National Renewable Energy Laboratory)
Historical Innovation, Status, and Challenges Ahead To Motivate a Grand Vision for Wind Energy
Wind energy has evolved over the last several decades from a niche technology to one that provides a significant share of electricity generation in grid systems across the world (Wiser and Bolinger 2018; Wingfield 2017; Kleckner 2017). A key factor in the success of wind energy to date is innovation that has increased energy production for a given project while simultaneously reducing overall wind turbine and power plant costs (Lantz et al. 2012). In other words, innovation has lowered the cost of energy for wind power plants. Looking ahead, the prospects for increased global wind energy deployment are compelling but significant competition is also anticipated from solar photovoltaics (PV) and other energy resources. Moreover, as the share of wind and other variable renewable energy sources— such as solar PV—grow within electric grid systems, there is an increased need for power system services that extend beyond cost-effective energy. With continued innovation, wind power is expected to be capable of providing both highly competitive energy supply (Dykes et al. 2017) and power system support services that are essential to the reliable and resilient operation of the grid (Ackermann et al. 2017).
Recognizing the need for continued innovation in wind energy to enable the full potential for wind power in the future electricity system, a group of more than 70 international experts came together to examine: 1) the current challenges to continued large-scale deployment of wind energy, 2) the opportunities for innovation to address those challenges, and 3) the necessary research and development (R&D) to realize those innovations. This report documents the overall findings of these experts. The report also highlights trends in science and technology that are expected to enable wind energy R&D as identified by the experts.
Historical Wind Energy Development
Global electricity generation from wind was estimated at approximately 5% of total electricity supply in 2017 (Wiser and Bolinger 2018). To arrive at this level, global installations have grown rapidly since the turn of the century (Figure 1). By the end of 2017, global installations of wind power capacity exceeded half a terawatt (Global Wind Energy Council [GWEC] 2018).
Growth in wind energy has been spurred by policy supports in different locations around the world. However, as global installations have grown, innovation driven by technology scaling, technology learning, and R&D investment have led to a corresponding drop in the levelized cost of energy (LCOE). Figure 2 illustrates how costs have generally fallen through time. As of 2016, a composite characterization of wind power costs among Northern Europe (e.g., Denmark, Germany, Ireland, Sweden, Norway, and the European Union) and the United States indicated an LCOE of approximately $50/megawatt-hour (MWh) for new installations.
The main drivers for LCOE reduction have been technology scaling to larger wind turbines coupled with innovation in several areas of wind turbine and plant design, operations, and reliability (Wood Mackenzie 2018; Lantz et al. 2012, Wiser et al. 2016). In terms of scaling, turbines have grown in rotor diameter, power rating, and hub height consistently since commercial deployments first began in the 1980s. Rated power has increased by a factor of approximately 30-50 for land-based machines such that wind power plants today can produce far more energy with a much smaller number of machines. These size increases have led to significant turbine- and plant-level economies of scale. At the same time, rotor diameter and hub heights have also increased. These changes allow turbines to capture more energy at greater heights above ground level where the wind resource quality is better. As a result, the energy per turbine and per-unit cost has fallen—also contributing to lower LCOE.
Figure 3 illustrates how turbines have grown since the early 1980s. Although the basic platform configuration of the technology, three-bladed horizontal-axis upwind wind turbine on a monopole tower, has not changed, the size has increased 6‒7 times in terms of hub height, 6‒8 times in terms of rotor diameter, and 30‒50 times in terms of power rating. The size of wind turbines today rivals large-scale monuments and buildings while withstanding dynamic and complex loading throughout the turbine’s lifetime.
In addition to scaling and the associated performance improvements, the relative cost of wind power plant development and operations has also decreased. These reductions are, in part, a function of technology learning, R&D, and innovation but are facilitated by increases in turbine size, and in some locations, plant size, allowing for fewer moving parts overall and economies of scale with larger facilities. Combined, these trends have helped enable overall capital expenditures (CapEx) and operational expenditures (OpEx) per unit of energy to decrease over the decades (Wiser and Bolinger 2018; Lantz et al. 2012).
An important example of the innovation that has evolved in wind energy is evident in wind turbine blade designs—which are far more sophisticated in aerodynamic design, use of materials, manufacturing process, special features, and structure than ever before. Figure 4 shows a comparison of the design features for a state-of-the-art blade design in 2015 versus one of the early mass-produced blades of the 1980s. A selection of design features is shown, including custom airfoils that were developed specifically for wind energy applications; advances in aerodynamic design, such as optimization of the planform, solidity, and tip shape; and advances in reducing weight through load mitigation by coupled aerostructural design (e.g., passive twist bend coupling). Current blades also incorporate various add-ons that may improve aerodynamic performance, reduce structural loads, or mitigate aerodynamic noise produced by the turbines (e.g., trailing-edge serrations).
Typical blades of the first generation of large-scale deployment turbines in the 1980s had a length of around 7.5 meters (m) (rotor diameter of 15 m) and weighed roughly 1 ton for a machine rating of 55‒65 kilowatts (kW). Without innovation, scaling of these blades for current large-scale offshore machines of roughly 6 megawatts (MW) in power rating and 154 m rotor diameter (75-m blade) would result in blade weights of nearly 1,000 tons. However, with innovation, a blade of this size in 2015 weighed only 80 tons. Thus, the rotor weight scaled with rotor diameter by an exponent of closer to 2 rather than an exponent of 3, which would have been the case without technology improvement. The “square-cube law” is known in the wind community as the rule that as you scale the size of the rotor diameter, the power increases by a power of 2 (power is directly proportional to rotor area) but the mass of the blade would increase by a factor of 3 (proportional to the volume increase). Through innovation, the blades have become slenderer and less material intensive such that the industry has been able to “beat the square-cube law” as rotor sizes have increased. Innovation in blades as well as the rest of the system have resulted in substantial cost savings on a per-unit energy production basis.
Lower LCOE driven by these technological innovations has given rise to wind energy projects that are now competitive in a growing number of regions of the world (Wiser and Bolinger 2018; Lazard 2018). Depending on the resource quality, wind energy may be the most cost-effective new electricity generation resource available. According to Lazard’s Levelized Cost of Energy Analysis (2018), which estimates unsubsidized energy costs for an array of electricity generation sources ranging from $29‒$56 USD/MWh for wind energy can be compared to $41‒$74 USD/MWh for combined-cycle natural gas generation, and $36‒ $44 USD/MWh for utility-scale solar PV energy (Lazard 2018). It is important to note that these LCOE comparisons do not consider system value and so cannot be used in isolation to assess competitiveness.
Challenges to Future Wind Energy Deployment
Continued growth of wind energy deployments may require continued technology innovation. Even as wind energy has become among the most competitive new sources of electricity generation, persistent challenges could limit continued growth of wind energy.
One of the most significant challenges to continued large-scale deployment of wind energy has and continues to be LCOE competition from other electricity generation technologies. In recent years, the cost of energy for natural gas and solar PV have dropped substantially (Haegel et al. 2017; International Energy Agency [IEA] 2018; Fu et al. 2018; Lazard 2018) and cost of energy for coal remains low as well. Although utility-scale wind power prices remained lower than for solar PV in 2018 for some projects (Lazard 2018), depending on the region of world and availability of respective wind or solar resources, LCOE for utility-scale solar PV can be lower than utility-scale wind energy. The relative forecasts of solar, wind, and natural gas prices have a significant impact on the expected future global electricity generation portfolio (Mai et al. 2017). Thus, for wind energy to remain competitive, further efforts to drive down LCOE through research and innovation will be needed.
At the same time as LCOE has been decreasing, integration challenges in the broader electric system have been successfully addressed in many markets, thereby enabling wind energy generation to grow to more than 10% of electricity consumption in at least eight countries and more than 30% in two: Portugal and Denmark (Wiser and Bolinger 2018). Moreover, subnational system-level instantaneous wind power share has frequently exceeded the 50% threshold in several U.S. systems (see, for example, Wingfield 2017; Kleckner 2017). Generation in Denmark has exceeded 100% of the entire national electricity demand on some days during and since 2015 (Nelson 2015).
However, wind energy deployment is still challenged on several fronts by concerns about the ability to integrate a variable resource into the electric grid system in a reliable, resilient, and sustainable way. Current market structures based on marginal operating costs respond to renewables with a “free” fuel source that supplies electricity at low marginal costs by lowering energy prices when large amounts of wind are available. This therefore reduces the available revenue for all electricity generation sources (including wind energy), and especially reduces the system value of wind energy as the share of wind energy generation increases (Hirth 2013; Helisto et al. 2017; Ahlstrom et al. 2015; Wiser et al. 2017; ZamaniDehkordi et al. 2016). As more wind energy, near-zero marginal cost, and nondispatchable operation is deployed in a given energy system, energy prices and revenues to generation assets fall, leading to a negative feedback loop in which wind energy cannibalizes its own profit opportunities. Ensuring enough revenue for capital recovery and availability of critical reliability services may require a change in electricity market structures to explicitly consider additional elements of overall electricity system operation reliability—namely capacity and system service markets (Ahlstrom et al. 2015).
For wind power plants to remain competitive as market structures and revenue streams evolve, there may be an increasing emphasis on the value of wind power plants in providing capacity value and other system services. To ensure profitability and become a primary source of electricity generation in the future grid system, wind power plants may need to seek value in forward capacity markets, provide “dispatchable” operation in peak energy pricing periods, and participate in ancillary service markets. Thus, innovations for wind energy may need to target not just reduced LCOE but also increased value to the electricity system. Wind plants that provide ancillary services will likely need to forgo some energy generation opportunities to deliver the service. For such an outcome to be financially feasible, either the market needs to compensate for that missed opportunity, or the capital cost of wind systems will need to be low enough that the missed energy revenue does not adversely impact energy cost.
Large-scale deployment of wind energy in the future will also need to address concerns related to nontechnical/nonmarket impacts. Social acceptance, transmission availability, and a variety of related system, social, and environmental factors are expected to influence physical design needs and constraints and ultimately the deployment of wind turbines and plants. Although these elements are also critical to the current deployment of wind energy, they extend beyond the scope of the current work. In addition, discussions around policy strategies that attempt to affect the evolution of the electricity system are beyond the scope of this effort. Instead, the focus of the current work is on research-based innovation that can affect the economics of wind energy from an LCOE and a system-value perspective to support wind energy deployment reaching shares of 50% or more in the global electricity system…
The Future of Global Energy and Wind Energy Abundance
The IEA Wind TEM #89 “Grand Vision for Wind Energy” workshop identified trends of the energy system in the year 2050 to understand and subsequently define the future requirements for wind power plants operating in this hypothetical future. This approach helped determine the innovations and R&D efforts needed to realize the future potential for wind energy.
Context of the Grand Vision Including Global Megatrends
To characterize the effort, a wider context regarding global megatrends in terms of society and technology development was needed. Several analyses about global megatrends have been made in recent years to better understand how the world may look in 2050. Among these megatrends is continued population growth coupled with an increased standard of living for broad swaths of the global populace as well as increased mobility and electrification; continued sizable demands on the global agricultural and modern infrastructure systems are also anticipated (United Nations). Adding to these are trends in decarbonization of the electricity, heating, and transport sectors, as well as industrial use of energy and carbon. Moreover, climate change adaptation and mitigation are expected to support deployment of clean energy solutions, including wind power, in the decades to come (IEA 2018; DNV GL 2018).
Deployment and Social Acceptance of Wind Energy
Social acceptance and other aspects of large-scale deployment of wind energy were outside the scope of the workshop but are critical to the realization of the full potential of wind energy. As with all energy technologies, deployment of wind energy, especially at large scales, will have increasing impacts on society and the environment. In this vein, it is expected that social acceptance, transmission availability, and a variety of related system, social, and environmental factors will influence physical design needs and constraints for the technology, thereby ultimately affecting the deployment of wind turbines and power plants. We anticipate that with time and increasing wind power share around the globe, the ability to design and optimize wind turbines and plants to best integrate with the landscape, existing infrastructure, and local social and environmental considerations, as well as multiple landuse, ocean, and airspace needs, will become increasingly necessary.
Planning, policy, environmental, and broader social science research will help realize a 21st century society in which wind power contributes substantially to the global energy system. Although these additional factors and implications are an essential pillar in enabling the energy future envisioned by the participants in the IEA Wind TEM #89, a full elaboration of these social and environmental challenges and associated research needs is beyond the scope of this report. The authors suggest considering a similar comprehensive effort focused on these issues that complements the current effort, to address all the opportunities and challenges related to the future of wind energy.
The Future Electric Grid Sets New Requirements for Power Generation Sources, Including Wind
Continuing recent trends, increasing shares of solar and wind energy production are expected to be integrated into the world’s energy and electrical systems. Many energy scenarios show wind power as becoming one of the main sources of electricity by midcentury. The IEA World Energy Outlook 2018 forecasts that renewables, led by wind and solar PV, will make up two-thirds of new power plant investments through 2040, leading to a scenario in which they provide 40% of global electricity generation in that year (IEA 2018). Bloomberg New Energy Finance forecasts similar trends with renewables making up 72% of global electricity generation investments through 2040; wind and solar energy provide 34% of global electricity generation in that year (Bloomberg New Energy Finance [BNEF] 2017). Even if solar energy tends to dominate global investment and installed capacity of these scenarios, electricity generation is estimated to be dominated by wind energy in the northern hemisphere (Pursiheimo et al. 2018). Broadly, analyses predict a share of renewable electricity in the generation system of at least one-third globally by 2040 (Energy Information Administration [EIA] 2017; BP Energy Economics 2018; BNEF 2018; IEA 2018). An even higher wind energy generation scenario comes from the International Renewable Energy Agency (IRENA), which estimates over 60% of global electricity generation in 2050 from solar and wind energy alone (26% and 36%, respectively) (IRENA 2018).
A recent study from DNV GL, a global services corporation for the maritime, oil and gas, renewable energy, food, and healthcare sectors, found that their “central” case for the electricity generation portfolio in 2050 was comprised of more than two-thirds renewables, with approximately 29% coming from wind energy and 40% from solar PV (DNV GL 2018). Figure 7 shows the composition of the electricity generation mix forecast by DNV GL from 1980 through 2050. In 2050, the projected electricity generation from onshore, or land-based, and offshore wind combined is 29%. A key feature seen in future energy scenarios is that in addition to a renewable-energy-dominated electricity system, there is significant electrification of other energy sectors (e.g., transport, heating), such that electricity demand doubles and the role of renewable energy in larger energy systems is even more critical…
The energy sector is undergoing a paradigm shift. By 2050, many predictions identify a future electric grid system in which renewables make up a significant share (30% or more) of overall electricity generation. In the fall of 2017, wind energy experts from around the world came together to look at an even grander vision of the future electricity system where wind energy could produce a majority (>50%) of global electricity generation. This “Grand Vision” for wind energy pushes beyond even the most optimistic forecasts; however, to realize this future, significant innovation is needed to reduce the cost of wind energy and increase the value it provides to the electricity system.
Through a series of meetings, wind energy experts identified innovations in several areas: manufacturing and industrialization, turbine technology and design, atmospheric (and metocean for offshore) science and forecasting, plant control and operations, grid integration, and offshore-specific technologies. Innovations in these areas would lead to reductions in wind cost of energy and/or improve the value that wind energy has for the electricity grid in providing more reliable and dispatchable energy, higher capacity value, and improved grid services for greater reliability and stability. The groups then discussed the R&D efforts that would help accelerate and enable the development of these innovations.
This report documented the findings for each innovation area to realize a future electric grid scenario with high shares of wind energy. The authors then synthesized the discussions on R&D challenges into a high-level list of grand R&D challenges by area. Throughout all the research areas, there were common themes that surfaced: leveraging recent advances in data science, digitalization, and associated technologies, and creating multiscale and multidisciplinary modeling capabilities that could fully capture all of the complex coupling and interdependencies both within the wind power plant and the full electric grid system. Exploring these cross-cutting themes revealed a higher-level framework that could be used to coordinate and integrate wind energy research across the different areas to successfully address the grand R&D challenges.
The shear complexity and size of the wind energy science challenge merits such an integrated perspective and approach and emphasizes the need for an integrated wind energy science discipline. Future work, in the form of a follow-on journal article, will articulate more completely the different components of this discipline and discuss how execution of such an integrated research program will overcome the challenges set forth to realize the Grand Vision for Wind Energy. If successful, the resulting innovations can help realize a future electricity system with wind energy as its foundation.