How Renewables Could Help the Aviation Sector Decarbonise
- The aviation sector contributes to around 2% of CO2 emissions. The industry is aware this is an issue, and before the COVID-19 pandemic, the International Air Transport Association (IATA) set voluntary emission reduction targets.
- Electric aircraft are currently being assessed for their potential over short distances. However, it is more likely that hybrid aircraft will be the first to be commercialized—combining current jet engine technology with a battery-electric source.
- Biojet is currently the most certified type of sustainable aviation fuel, with eight production methods already being signed off by the aviation international standards organization. However, biojet fuels are expensive, and offsets will likely be the cheaper option for airlines as it allows them to meet their environmental obligations without spending more.
Progress is being made in many decarbonizing areas of the world’s energy matrix, thanks to the introduction of renewable power sources. But, unfortunately, the transport industry is proving to be much more difficult to decarbonize. Improvements are being made in the electrification of urban transport, but long-distance transport, such as aviation, is a struggle to electrify. In addition, the other green options such as renewable natural gas and green hydrogen are also proving to be challenging to commercialize—estimated to be at least a decade away until mass utilization.
The aviation sector currently contributes to around 2% of the world’s CO2 emissions and about 12% of all transport emissions, tallying to 915 million tonnes of CO2 in 2019. However, non-CO2 emissions from aviation also have a significant climate impact, causing almost two-thirds of net radiative forcing.
Before the COVID-19 pandemic, the International Air Transport Association (IATA) set voluntary emission reduction targets that included the following:
- Improving fuel efficiency by 1.5% per year from 2009 to 2020
- Carbon-neutral growth from 2020
- A 50% reduction in emissions by 2050 (based on 2005 levels)
The above targets have resulted in multiple initiatives have been implemented, including the significant investigation into powering the aviation industry through the use of renewable power sources. This article looks into how renewables could help decarbonize the aviation section.
Electric and Hybrid Aircraft
The propulsion depends on electric energy storage (batteries), hybrid energy (a mix of electric and fuel-based propulsion) or turboelectric (fuel-based energy).
This unique renewable technology involves electrically assisted propulsion using electric motors to drive some or all of the propulsion on the aeroplane. The propulsion depends on electric energy storage (batteries), hybrid energy (a mix of electric and fuel-based propulsion) or turboelectric (fuel-based energy). Electric aircraft are currently being tested for their potential over short distances. They assess factors such as vertical take-off and landing, use as urban transport, and flights for short distances over mountainous terrain.
As forged in the automotive sector, hybrid aircraft will likely be the first to be commercialized—combining current jet engine technology with a battery-electric source. For instance, a hybrid aircraft will use electricity for some of its propulsion (like for taxiing or take-off to provide additional thrust) but predominantly use fuel-based propulsion to accomplish cruising.
Sustainable Aviation Fuels
There are currently many ways to produce biojet fuels—with eight of them already certified by ASTM International (the aviation international standards organization).
Biojet (aviation fuel made from biomass) is currently the most certified type of sustainable aviation fuel. In the future, it may also be possible to produce synthetic aviation fuels from green hydrogen—but production is currently minimal and not very economical. The high costs are primarily due to the lack of demand for the fuels at the current price point resulting in biojet presently holding the most promise for cost-effective scale-up and use during the 2020s and 2030s.
There are currently many ways to produce biojet fuels—with eight of them already certified by ASTM International (the aviation international standards organization). The current high demand for biojet fuels is due to several facilities being modified or reconfigured and new facilities being built. There is, however, a need for strict long-term policies being introduced on an ongoing basis to push significant growth in biojet fuel research and uptake.
Some jurisdictions have biojet fuel-specific policies, but a more comprehensive, internationally relevant strategy is needed. Starting in 2021, The ICAO Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) aims to contribute to the sector’s environmental objectives. However, there are doubts about whether this is just a short-term fix and will not significantly increase biojet production and use. Offsets will likely be the cheaper option than biojet fuels as it allows airlines to meet their environmental obligations without the need for biojet fuels.
Decarbonizing the aviation sector by 2050 will require intensive action in multiple areas. There will need to be the application of many different solutions, including new propulsion systems, such as electric and hybrid aircraft and hydrogen. However, to achieve any emission reduction during the early 2020s and 2030s and intense reductions by 2050, the use of sustainable aviation fuels will be vital.
Frequently Asked Questions (FAQs)
Is biofuel considered a renewable energy source?
Biofuel is considered a renewable energy source. However, unlike other renewable energy sources, biomass can be converted directly into liquid fuels, otherwise known as biofuels. These clean energy alternatives can help meet the needs of the fuel for transportation. The two most common biofuels presently used are ethanol and biodiesel.
How much does aviation pollute?
If nothing is done, global aviation will generate around 43 metric gigatons of carbon dioxide emissions by 2050. This will constitute approximately 5% of permitted global emissions to keep global warming below 1.5 degrees Celsius.
How do solar-powered planes work?
Solar-powered planes have solar cells covering their wings. When the solar cells capture the energy from the sun, it powers the propulsion system, controls electronics, and charges the battery with any surplus energy.
What is the primary pollutant in aviation?
Nitrogen dioxide (NO2) is the primary pollutant of concern around airports. Nitrogen oxide (NOx) emissions form NO2 caused by surface traffic, aeroplanes, and other airport operations. PM2.5 is also a concern due to particulate emissions from jet exhausts.
Do aeroplanes pollute more than cars?
There is a misconception that aeroplanes cause more pollution than on-road vehicles. The truth is that although planes are bigger, use more fuel, subsequently emit a lot of air pollutants, they also carry many more passengers than a car does.