"Green" Jet Fuel From Sunlight Developed

A consortium of research institutions and corporations have announced a solution to one of the major obstacles to a sustainable world, carbon neutral fuel for airplanes. Also fire twirling.

While political obstacles may intervene, we now have the technology to provide electricity for virtually the whole world from non-polluting sources. With the rise of electric vehicles this can be transferred to land transport as well. However, air travel was always going to be a much tougher nut to crack. With air transport the fastest growing contributor to climate change this is a large and rising issue.

Suggested solutions include used cooking oil and mustard seeds but according to Dr Andreas Sizmann of Bauhaus Luftahrt, "Increasing environmental and supply security issues are leading the aviation sector to seek alternative fuels which can be used interchangeably with today's jet fuel, so-called drop-in solutions.” 

Jet fuel is made from a mixture of hydrocarbons to provide a low freezing point, anti-static and a flash point that makes it safe for transportation. However, the base is kerosene (paraffin), as used for gas camping fires and in lamps where electricity is not available. For all uses kerosene is currently produced from petroleum and predominantly made up of alkanes and naphthenes

In a quest for a travel industry that doesn't destroy the places people are trying to get to the European Union funded SOLAR-JET, bringing together five institutions in a quest to make kerosene from carbon dioxide, water and sunlight. While these substances contain all the elements required, conversion is a two-step process.

The SOLAR-JET team first converted the CO2 and H2O to a hydrogen/carbon monoxide mixture (syngas) using concentrated sunlight and metal-oxide catalysts. A technique for converting syngas to kerosene, the Fischer-Trosch process is already in widespread use.

"The solar reactor technology features enhanced radiative heat transfer and fast reaction kinetics, which are crucial for maximizing the solar-to-fuel energy conversion efficiency" says Professor Aldo Steinfeld of ETH Zurich.

The project is still at the proof-of-concept stage, and the price of fuel produced in this way is not yet clear.

The fact that kerosene can now be produced from carbon dioxide does not remove the need to phase it out from many of its current applications. Indoor kerosene use is a leading cause of respiratory disease in Africa and South Asia. Replacement with solar lamps can prevent around a million  deaths each year, as well as being dramatically cheaper in the long run. Moreover, the carbon black emitted by burning kerosene is a more potent greenhouse gas than carbon dioxide, so use of kerosene made from carbon dioxide would be carbon neutral without being greenhouse neutral.

Even for air travel, a sustainable fuel will not solve all the problems. Vapor trails and ozone emissions contribute almost as much to global warming as the fuel burned. Nevertheless with alternative choices for sustainable air travel in their infancy and still subject to question, the SOLAR-JET announcement could be a gamechanger if it can be done at a realistic price.