13 Dec The Unexpected Rise Of Natural Gas In Aviation
The way in which natural gas has changed the shape of the world is incalculable, and there is practically no industry that does not need a gas engineer and a pipeline at some level, even if some aim to reduce their dependence to only processes that absolutely need it.
As the world evolves, and the types of fuel needed to do business within it change, so too does the purpose of methane gas, and for every industry that finds an alternative to fossil gas, another industry finds that natural gas is the alternative they need.
One industry where this is starting to be particularly important is in the field of aviation, where liquefied natural gas is rapidly becoming a secure alternative whilst the future of the entire industry is still as yet unclear.
The Flight Of Natural Gas
Before discussing the history of aviation’s relationship with fossil gas, it is important to make it clear that the kind of aircraft most associated with gas and hot air never actually used methane.
Typically, gas balloons, hot air balloons and airships did not use flammable gasses to provide the lift nor the thrust for the machinery, instead relying on a huge area of gas that was lighter-than-air that would then be powered by a propeller.
This engine could theoretically have used natural gas but was more likely to use some form of petrol or propane gas instead to power its propeller, if not some of the gas used for lifting such as hydrogen.
In fact, flammability was an undesirable trait, and part of the reason for the end of the airship era was because the flammability of the cheapest and most popular gas used in their operation led to several dramatic and catastrophic crashes, most notably the LZ 129 Hindenburg on 6th May 1937.
It would take a long time for both hydrogen and natural gas to be considered again as a fuel source for aircraft, with a dedicated and versatile fuel used to power the now-ubiquitous jet engines that made heavier-than-air flight possible.
In fact, between the crash of the Hindenburg and the first flight that used natural gas, over half a century passed in one of the most rapidly evolving technological and cultural periods in the history of humanity, when the modern world was born.
The first plane to run on natural gas was part of a decades-long experiment by the Soviet Union-owned Tupolev Design Bureau.
At the tail end of the USSR, Aviator and Tupolev designed and built the Tupolev Tu-155, an experimental aircraft that used cryogenics and had a wide range of world firsts.
It was the first plane to have a cryogenic system to supercool otherwise gaseous fuels. It was the first aircraft to make a flight powered by hydrogen, and it was also, arguably most importantly, the first plane to make a flight using liquefied natural gas.
Initially, the plan was to skip a step and see how effectively a plane could fly using purely hydrogen fuel, first with just one of the three Kuetsov NK-88 engines being fueled by hydrogen fuel before expanding the system further.
However, this was in 1988, deep in the Perestroika era of the Soviet Union and well into the communist bloc’s death throes. Liquid hydrogen at that point was prohibitively expensive, even more so than its relatively high-cost today.
By contrast, liquefied natural gas could take advantage of the same systems, and was far cheaper and far more plentiful.
The system even showed a lot of promise as over 100 flights were made before it was put into storage, and a planned follow-up plane was cancelled after the Soviet Union collapsed entirely and the Berlin Wall fell.
Tupolev has continued to run development programmes, encouraged by the lower cost compared to jet fuel and the fact that the cryogenic process used to make LNG liquid in the first place could keep the engine air cool instead of relying on an intercooler system.
In the 2010s, LNG and compressed natural gas (CNG) were being considered for use in aircraft once again, given that there is a far greater supply of fossil gas than jet fuel, and it would make for an effective stopgap whilst other sustainable aircraft fuels were developed.
It is cheaper, cleaner and lighter, a triumvirate that other alternative fuels have struggled to match
Planes such as smaller craft by Aviat and Chromarat have given gas aircraft a niche in the small plane industry, but larger airlines could potentially take advantage of this low weight to help with the complex fuel management calculations endemic to long-haul flights.