Transport constitutes approximately 20 percent of global energy use — a figure that is set to grow — and a new study published by physicist Jo Hermans in MRS Energy and Sustainability — A Review Journal has identified liquid hydrogen as a realistic option for what can be considered the most problematic modes of transportation in terms of sustainability — air travel.
While Professor Hermans of Leiden University’s Huygen’s Laboratory admits that traditional oil-based fuels such as gasoline, diesel and kerosene are both convenient and boast an appealing energy-to-volume ratio, liquid hydrogen could offer a potential solution for sustainable air travel in the future.
He argues that:
- Handling of liquid hydrogen would be carried out by professionals, which reduces the safety issues involved with the substance to the same level of risk involved in handling kerosene.
- Liquid hydrogen itself is very light — in fact, it is in a gaseous state at ordinary temperatures — which is an important advantage for air travel.
- The disadvantages of “boil off” created by the low boiling point of liquid hydrogen would be reduced in air travel because of the low outside temperature at cruising altitudes.
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Herman discounts the use of solar power for air travel without revolutionary changes in the airplane concept, but concludes that it seems wise to extend the availability of oil products as long as possible. However, he argues that the low cost of kerosene is a huge disincentive in this respect, saying that it “triggers much unnecessary air travel. A worldwide tax on kerosene — if at all politically possible — should be something to pursue.”
With regards to road transport, however, the physicist claims that liquid hydrogen is not a viable option given the safety issues around handling it, and that electric vehicles offer the most promising solution. Improvements in battery performance and supercapacitors are, he says, imperative. Of direct driving using solar power, Hermans remains skeptical, despite advances being made by students at the Eindhoven University of Technology, who have designed and built a four-seater solar-powered family car that can be driven indefinitely under clear skies at a speed of about 43 km/h.
Alternatively, Herman suggests that the most efficient way to reduce energy use in the future is simply by reducing mobility, for example, by having shorter distances between the workplace and home. “In other words, urban planning provides an important key,” he concludes.
Hermans’ article “The Challenge of Energy-Efficient Transportation” can be read in full here.
Liquid hydrogen isn’t the only potential viable alternative for air travel — the culmination of the ‘On Wings of Waste’ flight which traveled 500 miles from Sydney to Melbourne on a unique fuel blend made from 10 percent end-of-life plastic derived from the ocean and landfill sites has proven that transformed end-of-life plastic can be used not only be used to fuel air travel, but can be used for any diesel engine.
“After years of preparation and many ups and downs, we’ve finally shown that the eight million tons of plastic dumped into the oceans each year can be put to good use,” said Jeremy Rowsell, the British pilot who completed the ‘On Wings of Waste’ flight.
“We blended 10 percent of fuel manufactured by Plastic Energy with conventional fuel and the flight was a dream.”
A thermal anaerobic conversion process is used to create the plastic-derived fuel. It involves heating plastics in an oxygen-free environment to prevent them from burning (and the subsequent release of toxic emissions), then breaking them into their component hydrocarbons to create the equivalent of a petroleum distillate, which can then be separated into different fuels.
The widespread use of the ’10 percent solution’ could present a unique opportunity for the aviation industry. For example, on a 10,000-mile flight, a 747 aircraft burns 36,000 gallons of fuel. If 3,600 gallons of that fuel came from plastic waste, it would essentially be diverting 18 tons of plastic from the oceans or landfills. According to edie, if this was applied on the 1,200 flights that leave London’s Heathrow Airport every day, it would equate to 21,600 tons of plastic waste being transformed into fuel every 24 hours from that airport alone.
On Wings of Waste are now looking to secure backing from investors in order to build a recycling plant in Australia, which they hope will spur a shift in the way consumers dispose of single-use plastics.
“Plastic breaks up into small particles, mixing with the plankton at the ocean surface. Plankton is at the heart of the food chain and provides us with more than half of the oxygen we breathe — our oceans keep us alive,” said Jo Ruxton, a member of the On Wings of Waste team.
“We can’t yet safely remove plastic particles from plankton that lives in the ocean, so we must stop dumping plastic waste in the ocean. There are estimated to be 5.25 trillion participles of plastic floating — mainly at the bottom — of the world’s seas.”