In line with global emissions targets, energy markets are moving ever more quickly to take up renewables. Such a move is obviously important to ensure carbon reduction targets can be met.
This does however create an issue—one that’s not been given the attention it deserves—of the impact this has on the conventional power plants that are “balancing” the uptake of new energy sources by providing energy when the sun doesn’t shine or the wind isn’t blowing. This requires these power plants to undergo cyclic operation to compensate for this; these moments lead to new challenges for the engineering systems and materials involved. Put simply, conventional power plants provide consistency as an energy source; renewables like wind and solar are intermittent. That’s not only a problem in terms of the absence of large-scale energy storage technologies to act as a buffer and deliver constant supplies, but even more essentially, the cycling of conventional power plants presents a whole set of challenges around what this does to the condition and performance of the infrastructure.
Current large-scale power generation relies on turbines that drive generators, such that these are at the core of the challenge for the energy sector. Economies of scale mean that larger power plants, and hence turbines, are more efficient, with smaller heat losses. However, they are also slower to start up and shut down. Switching on and off such power plants to fill the gaps in generation left by intermittent sources, means more frequent heating and cooling, inducing fatigue in the systems and potentially greater degradation over time. Furthermore, a switch to novel, lower-carbon fuels means changed combustion environments and potentially different deposits on the surface of the turbine and associated systems, resulting in more corrosion. That means shorter life cycles for infrastructure, more regular maintenance, even more downtime—and the potential need for much greater capital spending, not as a one-off but as part of strategic planning.
Significant effort is being made to understand how materials and structures will respond to the new combinations of stress and the environment for existing technology, as well as new designs with unconventional aggressive environments from alternative combustion systems and fuels.
Industry and academia are coming together at Parsons 2019 (The 10th International Charles Parsons Turbine Conference, Sept. 16–18, 2019) to share the latest thinking and work on developing technologies in turbines. Parsons—held every four years and named after the maverick behind the evolution of turbo-machinery, Charles Parsons—involves experts from the energy, aerospace, marine offshore, and engineering sectors around the world.
At Cranfield, for example, work has been focused on better understanding the specific nature and extent of the degradation involved, the effects of high temperature and oxidation up to 1,200C. In this way, we’re able to anticipate the repairs needed and the most cost-effective approaches: the potential for using cheaper and lighter components, for making use of novel advanced manufacturing and additive manufacturing techniques, so that the more-regular repairs can be made more easily and in situ. Other research is looking at new types of power cycles and how materials perform, for example, the opportunity for using novel high-density fluids where there is no separation between gas and liquid—meaning there are no droplets and less corrosion.
Further examples of emerging technologies and solutions include investigating state-of-the-art materials production, minimizing internal defects and thus the source of materials degradation; the use of advanced characterization and assessment technologies to more-rapidly assess power plant component responses; or models for the degradation of materials under anticipated and emergent operating conditions.
—Dr. Joy Sumner is senior lecturer in Energy Materials with the Centre for Thermal Energy Systems and Materials. Parsons 2019, organized by the Institute of Materials, Minerals and Mining, will be held Sept. 16–18, 2019, at Cranfield University, UK.