Cienciaes.com: Great challenges in the science of wind energy. We speak with Xabier Munduate.

2019-10-25 00:39:36

Society increasingly demands clean and affordable energy that will cover the needs of humanity in the coming decades. With a growing population that will approach 10 billion people on the planet by mid-2050, energy needs will multiply. According to estimates by Bloomberg New Energy Finance (BNEF) global annual demand for electricity could exceed 38,000 terawatt-hours per year by 2050, up from about 25,000 terawatt-hours consumed in 2017, an increase of 50%.

The reduction of greenhouse gases necessary to face the problem of global warming, in which we are immersed, will require the replacement of polluting energy sources with clean sources, such as solar or wind energy. Many of the energy sectors traditionally based on the burning of fossil fuels, such as heating or transport, will have to be replaced by others powered by electricity produced from clean sources. A good example that supports this trend is the great revolution that electric vehicles are promoting compared to traditional combustion vehicles.

It is estimated that only the energy obtained from the wind should supply a third of the world’s energy demand by the year 2050, an objective that will require overcoming some challenges as defended in the article Grand challenges in the science of wind energy. recently published in the scientific journal Science, one of the authors of which is our guest on Talking to Scientists, Xabier Munduateresearcher of Wind Energy Department of the National Renewable Energy Center.

The first of the great challenges that will have to be overcome for wind energy to reach the objectives set for 2050 is to understand in a deeper way the physics of the atmospheric flow so that the knowledge allows a greater use of wind energy in the wind farms. The energy of the wind is due to the uneven heating of the Earth’s surface and to the forces derived from the Earth’s rotation, or Coriolis forces. Depending on the place, the winds follow their own dynamics that must be understood to obtain maximum use of energy. On land, a high place is not the same as a plain or a desert, and over the oceans factors such as the sea or land breeze, proximity to land, air temperature or the height of the waves play a role. U each place produces daily variations between day and night, or different speeds at different heights. To all these factors that we can call “local” we must add others that have much larger dimensions due to global meteorological phenomena. Thus, in-depth knowledge of the physics of wind at different spatial and temporal scales will make it possible to optimize resources and obtain better performance in the future.

The second challenge involves the science and engineering of wind turbines, especially those that, due to their dimensions, are among the largest machines in the world. A modern generator is built on a foundation that supports a cylindrical tower that supports, at about 100 meters high in a medium wind turbine, a box or gondola that is coupled to three blades that can have lengths of about 60 meters per term. half. The blades rotate by the action of the wind at slow revolutions. The revolutions of the blades are transmitted to the nacelle where the revolutions are raised to very high ones so that a generator converts them into electricity. The construction of larger wind turbines, which exceed 200 meters in blade height, requires having tools with which the interaction of wind and blades can be modeled. The wind changes with height, the rotation speed of the tip of the blade is very different from the root, while the tip moves at speeds of 100 meters per second, the nacelle connection part barely moves. These factors and many others must be taken into account when designing large wind turbines, which must be more slender, with less rigid and lighter materials. These challenges require new designs, increased modeling effort, and an understanding of momentary deformations that occur due to the forces the blades are subjected to when they are moving.

The third challenge covers the optimization and control of wind farm fleets so that they work optimally within the electricity grid. The production of the wind farms has been increasing over the years and at the moment it can reach, at certain times, to cover the total electricity needs of the electricity distribution network at a given moment. Although these cases are sporadic, in Spain the average values ​​are 20% of the network capacity, in those moments of maximum production it can reach 100%. These changes require the study and adaptation of the relationship between the wind farm and the grid so that their connection is optimal at all times.

Xabier Munduate, a researcher at the Department of Wind Energy of the National Renewable Energy Center (Centro Nacional de Energías Renovables) talks about these challenges in detail during the interview.CENER), I invite you to listen to it.

Reference: Paul Veers et al., Grand challenges in the science of wind energy.
Science 10 Oct 2019:eaau2027 DOI: 10.1126/science.aau2027