There are several ways that planes can become net zero in terms of carbon emissions. One approach is to use alternative fuels, such as biofuels, which can significantly reduce the carbon footprint of aircraft.

Biofuels typically have a higher energy content per unit of volume than traditional jet fuel, which can result in more energy being produced per unit of fuel. High-grade biofuels, such as advanced biofuels, can be quite efficient in terms of reducing carbon emissions compared to traditional jet fuel. Advanced biofuels are made from non-food feedstocks, such as algae or woody biomass, which can have a much lower carbon footprint than biofuels made from food crops. Additionally, biofuels can also have lower emissions of pollutants such as sulfur and particulate matter compared to traditional jet fuel.

The efficiency of biofuels can vary depending on the feedstock used and the specific production process. Some biofuels have been demonstrated to have a greater than 90% reduction in greenhouse gas emissions compared to traditional jet fuel, but it also depends on the entire production process and the way the biofuel is produced, transported and stored.

Overall, high-grade biofuels are seen as a promising alternative to traditional jet fuel that can reduce carbon emissions, and they are actively being researched and developed. Currently, biofuels are being used in small amounts as a blend with traditional jet fuel. However, the development of advanced biofuels, such as those made from algae or woody biomass, has the potential to increase the amount of biofuels that can be used in aircraft.

Another approach is to improve the efficiency of aircraft through the use of advanced aerodynamics, materials, and propulsion systems. Additionally, aircraft manufacturers can offset the carbon emissions produced by their planes by investing in renewable energy projects or planting trees. The ultimate goal is to achieve a balance between the carbon emissions produced by the aircraft and the carbon sequestration or reductions achieved by these mitigation activities.