Most Promising Technologies and Aircraft Concepts for Environmental Performance Improvements: A Systematic Review
Abstract. A systematic review of the most promising technologies and aircraft concepts for reaching climate-neutral aviation is presented, based on a technology scouting for classification and benchmarking of their environmental performance. In a first step, a heuristic approach is used to analyse existing technology roadmaps on reducing environmental impact. The main levers commonly identified are technology advancements, operational measures, sustainable aviation fuel and demand management. The aircraft technologies from the aviation roadmaps are classified in a technology taxonomy in the categories aerodynamics, structural, systems and propulsion technologies and the entry-into-service is visualised in technology roadmaps. In a second step, an overview and categorisation of recent developments in advanced and disruptive (regional, short/medium and long-range) aircraft concepts is compiled. Environmental performance improvements can reach up to 40-50% (kerosene fuel burn and CO2) and 70% (NOX) compared to older reference aircraft, with reductions dependent on reference aircraft age. Hydrogen combustion offers zero CO2 while hydrogen fuel cells offer zero CO2 and NOX emissions. Different architectures are used for various ranges: Blended wing body and tube and wing (long-range), tube and wing (regional), and box-wing, double-bubble, strut-braced wing and tube and wing (short/medium range). While it is not possible to attribute a single reduction potential to a single technology feature, the most promising fuels are kerosene (conventionally, or in combination with batteries or fuel cells), sustainable aviation fuel and hydrogen. From the propulsion concepts, innovative turbofans (e.g. ultra-high bypass ratio turbofans) and innovative engines (e.g. hybrid-electric fans) had large improvements. In the field of aerodynamics, most applied technologies are high aspect ratio wings, riblets and laminar flow control, furthermore most concepts applied composite materials. For some aircraft concepts the climate impact was measured using climate metrics like ATR100 or GWP100, revealing trade-offs between fuel burn and climate impact or NOX emissions.