GLASGOW, (Reuters) – It requires a great deal of energy to lift a 300-ton aircraft full of people up into the skies and propel it at 500 miles per hour. It will be difficult to take off without adding greenhouse gasses to the atmosphere.

To help reduce global warming, the airline industry is responsible for almost 3% global carbon dioxide emission.

But with travel demand likely to add to the 100,000 or so flights daily, some worry they could struggle with that goal https://www.reuters.com/business/cop/something-air-jet-fuel-demand-ready-takeoff-2021-11-05.

Airlines claim they are optimistic. These are just a few of the strategies that they’re considering:

GREEN FUEL

The airline industry believes its quickest path to net-zero is replacing jet fuel with “sustainable aviation fuel” (SAF) made from renewable sources, such as plants or used cooking oil.

The theory is that SAF could reduce flight emissions by about 80% depending on the way it’s made.

SAF, however, isn’t widely accessible due to its high cost. To bring down prices and increase supply, the United States and countries around the world are looking at subsidies. Some airlines mix small amounts of gasoline into their jet fuel.

Some other issues include the possibility that planes will not be able to run on SAF only, or if they can use a mixture. Petroleum-based fuel engines rely on oily properties to protect seals and gaskets, and lubricate internal components. However, it is not clear if SAF can provide this effect by itself.

Boeing (NYSE: ) has begun to investigate the matter and committed that its planes will be certified for SAF 100% by 2030.

OFFSETS

SAF is not able to replace gasoline fuel. However, at the very best it reduces emissions by around 80%.

The rest could be written off with carbon offsets – financial instruments that allow an emitter to pay someone else to cut emissions.

By investing in renewable energy, supporting tree planting, and other activities that reduce the amount of carbon dioxide in the atmosphere, offset credits can be generated. These investments are being made by airlines and other industries.

However, scientific uncertainties and a dearth of transparency as well as international quality standards make it impossible to know if offsets will reduce emissions.

The U.N. climate summit is in Glasgow. Its participants are seeking to resolve the problem by agreeing standards for government-run carbon market, which will likely inform voluntary rules. Delegates aren’t sure that a deal will be reached.

DIRECT AIR CAPITAL

United Airlines is against carbon offsets. Scott Kirby (NYSE 🙂 describes them as “the highest form of greenwashing”.

Instead, UA will be betting on direct-air capture (DAC), a still under development technology that would capture carbon dioxide from the atmosphere and store it underground.

U.S. Airlines is part of 1PointFive Inc’s Texas project. It hopes to establish the first commercial direct-air capture facility that can remove 1 million tonnes CO2 each year.

This technology is still not scaleable. The technology is expensive and can only capture one ton CO2. Many of the previous carbon capture-and-storage (CCS), efforts failed.

Kirby stated that he believes the 1PointFive Project will succeed, but isn’t certain if it will prove cost-effective.

ELECTRIC AND HYDROGEN

The possibility of scaling up battery power to power airplanes is another option being explored. Also, hydrogen fuel that has been made using renewable power may be possible.

However, the technologies are far from ready for commercialization. The batteries and hydrogen fuel remain heavy.

Rolls-Royce (OTC:) held a 15-minute test flight of a small electric plane in September, calling it a “milestone on the aviation industry’s journey towards decarbonization”.

The engine maker stated that it expected a market within the next few years for electric “flying taxis”, but longer distance flights will likely require more advanced technologies.

Airbus claims that it will build the first hydrogen-powered commercial plane by 2035.