The aviation industry is making deliberate efforts to address its environmental impact. Notable examples include reduction of aircraft fuel consumption through aircraft design (such as wingtips), operational efficiency (such as optimized routes) and wise energy and water use in manufacturing.
Materials and process science has been at the forefront of this effort as well. For example, carbon-fiber-reinforced polymer composites have made lighter airframe components possible, contributing to at least a 14% to 15% reduction in fuel consumption and thus carbon dioxide reduction. This is best demonstrated on the Boeing 787 airplane family. With the usage of composites exceeding 50% by weight, the Dreamliner is 20% to 25% more efficient than similar-sized airplanes and has saved 48 billion pounds of fuel since it entered service in 2011, compared to the airplane it replaces.
Likewise, scientific studies have shown that sustainable aviation fuels — such as those derived from jatropha plants, forestry and agricultural waste — reduce carbon dioxide emissions by up to 80% over their life cycle compared to conventional jet fuel.
But we materials and manufacturing engineers can do more.
By taking a broader view focusing on reductions not only in the air (weight and fuel) but also on the ground, we can find improvements along the whole life cycle, from sourcing and selection of materials for design, through manufacturing processes, to the end-of-life process and upcycling, when discarded objects or materials are used to create a product of a higher quality or value than the original.
The following four emerging materials and manufacturing sciences innovations are examples of that holistic approach.
Design for Environment
Design for Environment is a method to minimize or eliminate environmental impact of a product over the life cycle. Effective Design for Environment consistently maintains or improves product quality and cost while reducing environmental impact. Concepts such as Cradle to Cradle emphasize renewable resources and sustainable life cycles. Design chemistry approaches select environmentally benign or least-impactful materials and processes as part of product design.
Thermoset composites are heroes in terms of weight reduction — widely used across many platforms — and therefore fuel savings and carbon dioxide reduction throughout airplane service life. The technology does present some challenges, as such resins are normally made with petroleum products, the manufacturing process can be time consuming and energy intensive from production to curing, and landfilling has historically been the main disposal method for polymer composites.
However, significant progress has been made on the science and technology of recycling composites (both cured and uncured materials). For instance, a method for vaporizing and dissolving resin developed by an industry partner company, UK-based ELG Carbon Fibre Ltd., has made possible a groundbreaking, 2018 Boeing partnership to recycle excess aerospace-grade composite materials. This is reducing solid waste sent to the landfill by more than 1 million pounds a year from 11 Boeing manufacturing sites.
Likewise, reduction and reuse opportunities, such as layup pattern design and respooled material remnants, improve our buy-to-fly ratios and reduce material consumption.
Energy Savings from New Materials and Processes
The inherent reusability (via reprocessing or recycling) of thermoplastics reduces energy consumption needed for storing temperature-sensitive materials during production. In addition, various out-of-autoclave cure processes or alternative-energy-source processes are also being developed with promising early results. For example, MIT researchers recently developed a method that uses nanomaterial-enabled capillary pressure to produce aerospace-grade composites demonstrated at lab scale without autoclave, using only 1% of the energy currently required.
Disruptive Materials and Process Technologies
Finally, materials scientists are just now proving out the viability of experimental new concepts that could completely transform traditional practices, for instance, pulling carbon dioxide out of the atmosphere and converting it into high-value chemicals and materials that can be used for other purposes. Researchers have developed a nano-carbon dioxide harvester that uses water and sunlight to convert atmospheric carbon dioxide into methanol, which can be employed as an engine fuel, a solvent, an antifreeze agent and a diluent of ethanol. That could both reduce atmospheric carbon dioxide and gain some return on investment through product sales.
We have been developing innovative ways to remove paint from airplanes using lasers. Laser ablation occurs when material absorbs laser light and molecules are excited into the plasma state, thereby vaporizing the material. Laser depainting has several advantages over traditional chemical and media-blasting paint removal methods, while reducing over 90% of hazardous waste generated; eliminating ergonomic risk; and improving speed, quality and consistency.
Boeing and the aviation industry have made substantial progress, but we recognize there’s a lot more work to do.
Materials and manufacturing engineers are creating competitive advantages with mutually reinforcing environmental and economic benefits. The future looks even more promising. The early-career engineers and scientists who are increasingly taking a leading role in reshaping the climate sustainability movement will only grow the opportunities and scope to make the world better.
By Shanying Zeng, Boeing materials engineer
This article originally appeared in Innovation Quarterly; read more IQ here.