For more than two decades, nearly all renewable energy endeavors have incorporated the latest advances in turbomachinery design and turbomachinery manufacturing technology in an evolving effort to achieve and even surpass the economics of utility scale. Even mature turbomachines continue to be optimized for increments of better performance, efficiency, and energy conservation.
The world’s growing demand for renewable, sustainable, and environmentally friendly electricity is being provided by a broad and fragmented mix of green energy technologies. And virtually all refined, new, and proposed technologies for generating “green” electricity rely on improved designs for turbines, compressors, expanders, pumps, and fans to make them economically and environmentally viable. Solar, wind, hydro, tidal, wave, geothermal, and biomass energy resources require advanced turbomachinery designs to efficiently extract power from low-density flows, and to help justify the value proposition required for project success.
The engineering practices perfected in traditional turbomachinery development are now being applied to the newest generation of turbo green equipment being incorporated into virtually all the latest technologies for renewable and sustainable power. Some of these turbomachines are relatively mature, but continue to be optimized for even better performance, efficiency, and energy conservation, as well as for new applications and special requirements. And the turbomachinery implications for each technology reveal many opportunities for performance improvements as well as potential engineering breakthroughs.
Wind Turbines and Compressors
The United States leads the world in wind energy production with over 30,000 wind turbines, and new installations are rapidly increasing. Utility-scale commercial wind farms are now considered a mature technology that is economically competitive (even with coal-fueled generation) in select coastal locations. Micro wind-capture designs for onsite power generation are now being developed to operate on gentle and less consistent winds.
Other regions with strong and consistent winds include flatlands of the plains states (Iowa already produces 15% of its electrical power by wind turbines), plus various mountain regions and coastal sites including offshore islands. Some of the most lucrative locations, however, are remote and currently restricted by the lack of a high-voltage transmission line infrastructure, or limited to practical offshore installations in depths to only 30 meters.
Several radically different and highly efficient axial and radial impeller designs are now emerging that will effectively accommodate urban and onsite installations. To be viable, these small wind turbines will require much less wind for start-up (as low as 5 mph) and for optimum levels of efficiency.
Wind turbine turbomachinery is also being further refined to reduce the environmental impacts of noise and bird kills. New bird-safe blade shapes are especially needed for offshore regions within migratory flight paths. In another wind-power cycle, a wind turbine is used to drive a compressor. The stored compressed air is available to drive a turbine generator (or some other application) at times when needed.
As the ultimate renewable and sustainable resource, solar energy will continue to mandate incrementally improved (and less costly) photovoltaic installations, as well as inspire more effective solar-thermal technologies. Theoretically, capturing just 1/1000th of the sunlight falling on the Earth’s land masses could generate today’s total power consumption for all civilizations. Yet Germany, as the world leader, produces less than 1% of its electrical power from solar generation.
Both electrical and thermal-solar-powered energy systems will primarily focus on distributed generation for industrial/ commercial-scale sites. Utility-scale solar plants will require even more sophisticated and efficient turbomachinery to overcome several limiting factors that include only partial predictability for periods of solar generation and the amount of power that will be produced.
However, newer and better solar technologies using concentrated solar heat (at 400 °F and considerably higher) to drive a steam or gas turbine are promising to more effectively, efficiently, and practically utilize solar energy for electrical generation or to power some other thermal application such as an absorption chiller. The overlying turbomachinery challenge in all solar technologies and applications is to further advance turbine and pump efficiency in an effort to reduce their dollars- per-Watt installed cost.
Also, improved technologies for storing solar-powered thermal and electrical energy production are promising to make solar power practical and economically feasible in more regions. Significant breakthroughs in electrical and thermal storage could propel solar energy from a minor to a major contributor of green energy.