The electric revolution in aviation

Aviation is one of the fastest growing sources of greenhouse gas emissions, accounting for about 3.5% of global warming. To reduce the environmental impact of flying, engineers in the United States, Europe and China are working on developing and testing different types of electric aircraft, which use electricity instead of fossil fuels to power their propulsion systems. In this article, we will explore some of the most innovative and promising electric aircraft projects, as well as the main challenges and opportunities they face.

Solar-powered planes

One way to achieve zero-emission aviation is to use solar energy to power the aircraft. Solar panels installed on the wings or the fuselage can convert sunlight into electricity, which can then be used to drive electric motors or charge batteries. Solar-powered planes have the advantage of being able to fly indefinitely, as long as there is enough sunlight available.

One of the most remarkable examples of solar-powered planes is the Solar Impulse 2, which completed a round-the-world flight in 2016 without using any fuel. The Solar Impulse 2 has a wingspan of 72 meters, larger than a Boeing 747, and is covered with more than 17,000 solar cells. It can fly at an average speed of 70 km/h and carry one pilot. The Solar Impulse 2 demonstrated the feasibility and potential of solar aviation, but also its limitations, such as the low speed, the vulnerability to weather conditions, and the lack of passenger capacity.

Hydrogen-powered planes

Another way to achieve zero-emission aviation is to use hydrogen as a fuel. Hydrogen can be produced from renewable sources, such as water electrolysis, and can be stored in tanks or converted into liquid form. Hydrogen can be burned in a jet engine or an internal combustion engine, or can be used to power a fuel cell, which generates electricity and water as by-products.

One of the first hydrogen-powered planes to fly was the Tupolev Tu-155, a modified Soviet jet airliner, which made its maiden flight in 19883 Since then, several prototypes and demonstrators have been developed, such as the Boeing Phantom Eye, a high-altitude unmanned aerial vehicle, and the HY4, a four-seater aircraft that uses a fuel cell to produce electricity and water. Hydrogen-powered planes have the advantage of having a high specific energy, meaning they can fly longer and farther with less weight. However, they also face several challenges, such as the low volumetric energy density, meaning they need more space to store the fuel, the high cost and complexity of producing and distributing hydrogen, and the safety and logistics issues of handling a flammable and explosive gas.

Passenger drones

A more radical way to achieve electric aviation is to use passenger drones, which are electric vertical takeoff and landing (eVTOL) vehicles that can carry people or cargo between established or on-demand points. Passenger drones are similar to helicopters, but use multiple rotors or propellers to generate lift and thrust. Passenger drones can be either manually piloted, remotely piloted, or fully autonomous, depending on the level of automation and regulation.

One of the pioneers of passenger drones is EHang, a Chinese company that has developed the EHang 216, a two-seater eVTOL vehicle that can fly autonomously and offer urban air mobility services. The EHang 216 has 16 propellers and can travel about 35 km at a speed of 130 km/h. It can be controlled by a smartphone app or a command center, and has multiple backup systems for safety. EHang has conducted over 1000 test flights with human passengers, and has partnered with several cities and countries to launch its air taxi service.

Hybrid flying vehicles

A more pragmatic way to achieve electric aviation is to use hybrid flying vehicles, which combine the advantages of a helicopter and an airplane, and use a mix of electric and conventional propulsion systems. Hybrid flying vehicles can take off and land vertically, like a helicopter, and fly fast and efficiently, like an airplane. They can also switch between different modes of propulsion, depending on the flight phase and the energy availability.

One of the most promising examples of hybrid flying vehicles is the Lilium Jet, a five-seater eVTOL vehicle that aims to become a flying taxi. The Lilium Jet has 36 electric ducted fans, which can tilt and swivel to provide vertical and horizontal thrust. It can fly up to 300 km at a speed of 300 km/h, and can be recharged in less than an hour. It can be piloted by a human or a computer, and can operate from small landing pads or rooftops.

Conclusion

Electric aviation is still far from replacing conventional aviation, but it offers promising prospects for a more sustainable and accessible future. Electric aircraft can reduce greenhouse gas emissions, noise pollution, and fuel consumption, as well as open new markets and opportunities for mobility and transportation. However, electric aircraft also face significant technical, economic, and regulatory challenges, such as the low energy density, the high cost, and the safety and certification issues of electric propulsion systems. To overcome these challenges, more research and development, as well as more collaboration and coordination among stakeholders, are needed. Electric aviation is not a single solution, but a spectrum of possibilities, each with its own advantages and disadvantages. The best way to achieve electric aviation is to explore and experiment with different types of electric aircraft, and to find the optimal balance between performance, efficiency, and environmental impact.