Aviation takes almost one quarter of the UK national fuel budget, which all told adds-up to an annual equivalent of 57 million tonnes of imported oil. As supplies of conventional crude oil decline, the problem will present itself of how to keep the entire transportation sector running, and probably air-travel will decline, as a luxury that can be cut-back upon without impacting significantly on the quality of human life: e.g. cheap foreign holidays might be deemed less important than essential road-transport - getting people to work and the carriage of vital goods such as food. As I have discussed in many of these postings, the horizon that appears to me is one of a relocalisation of society (and indeed civilization) into small communities that are provided for by local farms and local businesses, in consequence of a serious shortfall in fuel, which therefore would eliminate much of our demand for cars etc.
This is a longer-run view, and I think that getting exactly to this point might take two decades or so, meanwhile airline companies are discussing how indeed their planes might be fuelled as the standard petroleum-based fuel (kerosene) becomes shorter in supply and increasingly expensive. Ethanol is one possibility, but it has the unfortunate property of absorbing water and consequently corrodes parts of the engine and fuel-lines, while the other contender, biodiesel, becomes extremely viscous either in cold weather or at the low temperatures encountered in-flight, e.g. around minus 50 degrees C at typical cruising altitudes of around 36,000 feet (around 11 kilometers, and below the stratosphere over most parts of the Earth, other than above its polar regions). There is also the problem that even by severely compromising food production - growing fuel-crops not food-crops - an equal to the present quantity of fuel derived from oil could not be met, not even for road transport, let alone aircraft.
The airline-giant company Boeing has released an 8 page report in which are extolled the virtues of a biodiesel made from algae. As has been discussed in some previous postings on Energy Balance, the apparent advantage of making biodiesel from algae rather than from crops is that perhaps 100 times more of it could be produced per hectare, whereupon the proposition does begin to look like a possibility. However, the site oilgae (link to the top left here) discusses the various difficulties that must be circumvented before this could become a reality. It is hence, another untested technology on the grand scale, although I remain optimistic that it could contribute to the final energy mix we will employ in the future. There are also fears that since the type of algae necessary will be a very tough and competitive strain, it could "escape" and contaminate the wider world, resulting in toxic algal blooms that are not readily controlled by nature.
Boeing envisages three distinct timescales over which alternative fuels could be introduced: near, mid-range and long-term. In the near term, a "drop-in" fuel is required, with which to substitute for regular fuel as soon as possible. It is thought that this might be a blend of kerosene and synthetic diesel produced by the Fischer-Tropsch process - i.e. from coal-liquefaction, or from synthesis gas generated by steam-reforming natural gas (principally methane). However, since peak-gas will follow peak-oil in just a few years, it would be a poor decision to rely on it as a source of fuel for very long. It is also significant that net CO2 emissions are double that from burning conventional fuel, when such synthetic fuel is employed, summing-up the carbon released in its manufacture and its final combustion. In the mid-term, 10 -50 years, Boeing proposes that biofuels will contribute more as a final percentage of jet fuel in a mix with synthetic diesel (Jet-A, or standard jet fuel). This does beg the question, as noted above, of where precisely this would come from. Ultimately, in our localised "society, in its state of "Oil-Dearth", growing food will be a more pressing issue than growing the number of runways at Heathrow Airport, say.
In short, it looks like a black-hole of fuel in general, from which the long-term view appears the most promising vista. On this note, Boeing are highly encouraging:
"With the potential for algae of providing 10,000 gallons/acre per year [...that's about 100 tonnes per hectare], some 85 billion gallons of bio-jet could be produced on a land-mass equivalent to the size of the US state of Maryland. Moreover, if these bio-jet fuels were fully compatible with legacy [existing] aircraft, it would be sufficient to supply the present world's fleet with 100% of their fuel needs (fig. 13) as well into the future."
However, would we not still need to produce large quantities of a blending fuel i.e. from coal-liquefaction, in order to maintain a manageable viscosity at the low operating temperatures? Boeing do not mention this, however, and so while details are sparse, they may have a jet-fuel up their sleeve with appropriate properties to meet that 100% as they claim.
Certainly, this would be a major breakthrough, and perhaps more details will be forthcoming, which I await with interest. Of further note is that the J Craig Venter Institute in Rockville, Maryland, has applied for worldwide patents to genetically-modify microbes with which to manufacture hydrogen and biofuels. The idea is that a very basic "stripped-down" microbe could be created by joining together blocks of about 50 letters, to make about 500 genes in half a million letters of DNA, and growing it in the "gut-bacteria" E coli. These many small pieces can be joined into a handful of bigger ones until finally two pieces can be assembled into the circular genome of a new life form. The synthetic DNA would then be added to a test-tube of bacteria from which, it is hoped, one out of one hundred billion would begin to move, metabolise and multiply.
Canadian ETC spokesman, Jim Thomas called on the world's patent offices to reject the applications, saying:
"These monopoly claims signal the start of a high-stakes commercial race to synthesise and privatise synthetic life-forms. Will Venter's company become the 'Microsoft' of synthetic biology?" One of his colleagues, Pat Mooney, remarked: "For the first time, God has competition. Venter and his colleagues have breached a societal boundary, and the public hasn't even had a chance to debate the far-reaching social, ethical and environmental implications of synthetic life."
(1) www.greenoptions.com/blog/2007/06/08/algae_biofuel_may_be_future_for_aviation, by Clayton Bodie Cornell, article "Algae Biofuel may be future for aviation."
(2) "Man-made microbe 'to create endless biofuel'", by Roger Highfield: http://www.telegraph.co.uk/core/Content/displayPrintable.jhtml