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Biofuels and sustainable transport -- Can biofuels be produced and used responsibly?
By Renfrey Clarke
June 16, 2009 -- For governments and vehicle corporations, the charm of biofuels used to be the promise they held out of a ready-made solution to transport-related greenhouse gas emissions -- a solution that might simply be dropped in, while changing almost nothing else. Freeways, suburban sprawl, four-wheel-drive family cars -- everything could remain. Only the fuel on sale at service stations would be different.
Biofuels, the promise to the public ran, would be ``clean and green’’, an environmental zero-sum. Although carbon was released to the atmosphere when biofuels were burnt, this was carbon that had been there earlier, before being taken up by the plants from which the fuels were derived.
Underlying the biofuels push was an unlikely premise. Within a relatively few decades, human beings were predicted to finish burning the Earth’s accessible resources of petroleum, resources which had been built up over hundreds of millions of years. After that, biofuels were supposed to meet these consumption levels year-by-year out of the Earth’s current biological production -- which would also need to sustain the living environment and feed human beings. The scale of the contradiction was pointed out by British writer George Monbiot in a 2005 article:
In 2003, the biologist Jeffrey Dukes calculated that the fossil fuels we burn in one year were made from organic matter ‘containing 44x10 to the 18th grams of carbon, which is more than 400 times the net primary productivity of the earth’s current biota.’ In plain English, this means that every year we use four centuries’ worth of plants and animals.
The idea that we can simply replace this fossil legacy -- and the extraordinary power densities it gives us -- with ambient energy is the stuff of science fiction.
By early in 2008, reflections such as these -- along with a good deal of
bitter experience -- were prompting a rethink. In economics as in nature,
critics of biofuels were pointing out, everything is connected to everything
else. When corn in the
The high corn prices encouraged farmers in the US Midwest to plant corn
instead of soybeans. As soybean supplies tightened, soy interests in
When such cascades of land use changes were taken into account, a 2008 study led by Timothy Searchinger of Princeton University and published in the journal Science concluded, the cost of using corn ethanol in greenhouse emissions per kilometre driven was almost double that of gasoline over a 30-year period. True, the carbon released when the ethanol was burnt had been in the atmosphere a few months earlier, not locked away in the Earth as with gasoline. But no fewer than 167 years would have to elapse before the savings made in this fashion would pay off the “carbon debt” incurred.
When peat-land rainforest in
Adding to the misgivings surrounding biofuels has been a 2008 study by a team led by Nobel prize-winning atmospheric chemist Paul Crutzen. This found that nitrogen fertiliser used in growing biofuel crops was converted by soil microbes to nitrous oxide at around twice the rate previously thought. Nitrous oxide (N2O) is a greenhouse gas hundreds of times more potent than carbon dioxide. Crutzen and his co-authors estimated that for rapeseed (canola) biodiesel, the relative warming due to nitrous oxide emissions was 1 to 1.7 times the cooling effect due to saved carbon dioxide emissions. For corn ethanol, the figure was 0.9 to 1.5 times. Only cane sugar ethanol (0.5 to 0.9 times) was likely to have a net cooling effect.
Nevertheless, biofuels remain entrenched in agricultural and industrial
practice in the European Union and the
An environmental atrocity, existing biofuels production is also economically disadvantageous for almost everyone except grain farmers and various sectors of the agribusiness, vehicle and energy industries. In essence, today’s biofuel industry survives only because governments, drawn by promises of a cheap fix for climate change and by the political lure of green credibility, have set mandatory targets for biofuel use and backed these targets with incentives.
Politicians and agroindustry in
In the setting of modern capitalist society, biofuels are proving a destructive, costly fiasco. But if society were more rationally organised, could biofuels be produced and used responsibly?
The answer is a cautious “yes”. But not all biofuels -- only those with a verified “cooling” effect. And because of the potential damage, a truly green biofuels industry would need to be regulated closely in line with the best science available. There would be no room for the profit-at-all-costs mayhem of “free markets”.
Biofuels can only be a rational choice if they do not cause a loss of
soil fertility, and do not compromise vital biosphere elements such as forests
and rivers. Nor must they be allowed to displace important sources of food
production. Also crucial is an understanding that on a world scale, biofuels
can only play a minor part in ending net emissions from the transport sector.
There is no way biofuels will ever power national transport fleets of today’s
size and type. Even if the entire
The transport systems of a sustainable future will rest heavily on public transport. Recent developments suggest that back-up will be provided by plug-in hybrid vehicles, yielding way progressively to purely electric cars and light trucks. For a time, production of biofuels will go largely to powering the hybrids on longer trips. Later, as electric-car batteries improve, the use of biofuels will increasingly be confined to specialised applications which require an energy source more concentrated than even the most advanced batteries can provide. These applications will include heavy trucks; agricultural machinery; locomotives, on rail lines with too little traffic to justify electrification; aviation, and shipping.
In large part, the biofuels used in a sustainable society will be
produced from sources and using technologies quite different from those of
today. At present, the main biofuel used is ethanol fermented from grain sugars
and starches -- that is, from potential foodstuffs. As indicated earlier, a
less flagrantly wasteful feedstock for ethanol than the corn mostly used in the
Depending on the degree and type of land use change, the carbon “debt” incurred by sugarcane plantings can be modest; Searchinger in his earlier-quoted paper speaks of it being repaid in four years if the plantings are on former tropical grazing land. Sugarcane, however, is a voracious consumer of water and of agricultural chemicals, with the latter washing freely into streams. When sugarcane is planted anywhere except on level ground, it contributes heavily to soil erosion.
Better than extracting sugars and starch from plants in order to make biofuels, many scientists have surmised, is to find ways to process all or most of the plants -- including the cellulose that is among their main building-blocks. This is the thinking behind “cellulosic” or “advanced” biofuels, projected as the next stage in the development of the biofuels industry. The US National Renewable Fuels Standard, which sets out the requirements made of fuel companies under federal legislation, effectively mandates that of the 36 billion gallons of biofuels to be produced in the US by 2022, around 20 billion gallons must be of this “advanced” or “second-generation” variety.
Woody plants are composed mainly of lignocellulose, made up of the polymer lignin and of cellulose, which consists of long chains of sugar molecules. Numerous microorganisms feed on plant matter by secreting enzymes which break down the cellulose chains into simple sugars, which can then be digested. In the conventional production of cellulosic biofuels, plant matter is treated with enzymes to break down the cellulose in the fibrous cell walls. Yeast is then used to ferment the resultant sugars into ethanol.
Cellulosic biofuel production has a range of important advantages over “first-generation” processes. Since most of the plant is used, much more fuel can be produced for a given input of water and fertilisers. Often, cellulosic waste from food crops can be used as the feedstock. If the feedstock is purpose-grown biomass, plant species can be used which do not require prime farmland and need not displace food crops.
As of April 2009, four cellulosic biofuels facilities were recorded as
operating in the
One line of investigation seeks to circumvent the high cost of the
enzymes by using a thermal process to break down the biomass. Pyrolysis -- that
is, heating in the absence of oxygen -- can be used to gasify the plant matter,
turning it into carbon monoxide, carbon dioxide and hydrogen; these gases are
then fed into a fermenter where bacteria convert them into ethanol and water. A
variant of this approach makes use of the Fischer-Tropsch process, devised in
the 1920s to make liquid fuels from coal. In this process, the gases are heated
to high temperatures and passed over a catalyst, producing hydrocarbons that
can be refined into petrol, aviation kerosene and diesel fuel. A sophisticated
version of the Fischer-Tropsch process has been developed for use with plant
biomass by the firm Choren in
Thermochemical biofuels production has potential for being combined with
the production of biochar -- that is, finely divided charcoal -- for soil
improvement and carbon sequestration. In any event, some additional use has to
be found for the large amounts of heat produced if the carbon emissions savings
are to be substantial, and the process acceptably cheap. For this reason and
others, current research on advanced biofuels concentrates mostly on biological
processes. A particular goal is to find -- or engineer -- micoorganisms that
both break down cellulose and secrete biofuels. While there have been no
dramatic breakthroughs, a number of intriguing leads have emerged. Technology Review in December 2008
reported that the
Much of the eventual demand for biofuels is not expected to be for ethanol -- which has a relatively low energy density, is difficult to transport and store, and generally needs to be mixed with fossil fuels -- but for fuels made up of longer-chain hydrocarbons that can substitute for petrol, diesel and aviation kerosene. In November 2008 the British Guardian reported the finding in a Patagonian rainforest of a tree fungus that consumes cellulose and “produces a range of hydrocarbon molecules that are virtually identical to the fuel-grade compounds in existing fossil fuels.”
In the near term, most of the biodiesel that reaches the market seems certain to be produced using more established methods. Since the late 1930s, chemists have known how to turn vegetable oil into biodiesel through the process of transesterification, in which the oil is processed using alcohol and an acid catalyst. Modern diesel motors will run on biodiesel without modification, creating fewer harmful emissions than with petroleum diesel.
World output of biodiesel -- almost all of it obtained from vegetable oils -- is growing rapidly, but remains much less than production of bioethanol. According to World Bank figures, about 6.5 billion litres of biodiesel were produced in 2006, compared with ethanol output that year of about 40 billion litres. About three-quarters of biodiesel production took place in the European Union; most of this came from rapeseed (canola), at grievous cost in nitrous oxide emissions. Of other biodiesel production, a great deal is derived from palm oil, with the lamentable environmental costs noted earlier.
Biofuel processors are looking intently for sources of biodiesel that are cheaper than the present ones, and that if possible, draw less criticism from environmentalists. A good deal of attention has been turned to the developing world, and to previously little-known plant species that have potential for improvement as oil sources. In 2007, the Indian corporation Nandan Biomatrix was reported to have selected eleven species for study as biodiesel feedstocks.
Among the outstanding discoveries has been the bush, or small tree, Jatropha curcas. Native to
The Indian government, the Yale Environment 360 site reports, has now “announced
plans to subsidise an intensive program to plant jatropha for biofuels on 27
million acres of ‘wastelands’ -- an area roughly the size of
Feeding enthusiasm for jatropha in the most recent period has been the discovery that its oil can be processed into a jet fuel that is compatible with aviation kerosene while also having a lower freezing point, lower specific gravity and greater energy density. The International Air Traffic Association has set a goal for its members to be using 10 per cent alternative fuels by 2017.
In the initial vision of the Indian government, the jatropha industry was not to distort the production of foodstuffs. Jatropha oil is inedible, and the plant was to be grown in place of rough pasture, or on otherwise unused land such as the strips bordering rail lines. The hunger of airlines for fuel, however, suggests that jatropha cultivation will now evolve quite differently.
Demand for land capable of growing jatropha will rise. Small landowners
will come under pressure to sell out to plantation interests, and land rents
will increase. Growing the new cash crop will become an economic necessity for
tenant farmers who traditionally have produced food crops. Inexorably, the
pressures of the market will shift jatropha cultivation from marginal and
degraded land to prime farming areas where high yields are possible; studies in
The growing of jatropha for jet fuel, this suggests, could set off a cascade of food shortages and environmental destruction similar to that created by corn ethanol. The impact will be exacerbated if, as seems likely, jatropha plantations are granted credits under emissions offset schemes.
Agronomists might well protest that the real problem here is not jatropha. Growing the plant -- a deep-rooted perennial that requires virtually no fertiliser -- creates very few emissions to detract from the savings its use provides. In principle, jatropha should fit well into traditional smallholder farming regimes, since it improves soil nitrogen levels and is well suited to intercropping with food plants. The inedible harvest residues could be used in local pyrolysis plants to produce electricity and biochar, further raising soil fertility and food output while sequestering carbon. The biodiesel would supply local needs and allow national oil imports to be cut.
The real problem, it emerges, is capitalism -- and specifically, the power of global capital to short-circuit rational development in poor countries.
Meanwhile, plants such as jatropha and technologies such as cellulosic ethanol have no prospects for supplying anything like the offsets needed for “business as usual” to continue in the transport area.
At current jatropha yields, New
Scientist calculated in August 2008, replacing world consumption of
fossil-based jet fuel would require the plant to be grown on 1.4 million square
kilometres, well over twice the area of
The calculations for transport fuels in total are no more comforting.
Assuming an average yield for biomass of 10 tonnes per hectare, New Scientist works out that “replacing
all current transport fuel with (biomass-to-liquids) would require more than 10
million square kilometres -- an area bigger than
Even cellulosic biofuels, this makes plain, cannot be more than a modest extender for fossil-based liquid fuels. The world’s current internal combustion vehicle fleet is nowhere near sustainable.
The success of biofuel interests in having their products mandated by
the US Congress defies logic on other counts as well. There is no reason to think that biofuels,
even from cellulosic sources, will be able to compete in terms of economic
costs or carbon emissions with electric vehicle technologies. The Australian
newspaper in May 2009 cited “running cost differentials between an
electric vehicle (2c/km) and petrol cars (10-14c/km).” A far more efficient and
desirable way to turn biomass into transportation, it is now emerging, is to
burn the biomass to create electricity that can be used in battery-powered
vehicles. According to Technology Review in May 2009, a
On every count, it seems, biofuels are doomed not to measure up, except as fuel for transitional hybrid cars and for the heavy-vehicle applications noted earlier. Unless, that is, something exotic comes to the rescue. In the speculations of some scientists and engineers, microalgae have been cast in such a role.
In the first years of the century physicist Michael Briggs of the
In ideal circumstances, microalgae -- familiar to most of us as pond scum -- can double their mass in as little as six hours, and produce many times more biomass in the course of a year than any terrestrial plant. Numerous algal species are at home in brackish or even hypersaline water; grown in deserts using groundwater too salty for irrigation, they can be raised without displacing conventional agriculture. Selected species contain as much as 50 per cent of oils by weight. Even species that are not optimal as oil producers create a range of other saleable products, protein-rich animal feed among them. Algae flourish in nutrient streams from sources such as sewage plants, animal feedlots or agricultural run-off; if algal culture can be used to offset or reduce the cost of wastewater remediation, their fertiliser needs may be obtained free of charge.
The signs in the algal equations, however, are not all pluses. Briggs acknowledges, then ignores, the fact that the Aquatic Species Program was seeking uses for the carbon dioxide in flue gases from fossil-fuelled power plants. The impressive figures for algal biomass production published by the National Renewable Energy Laboratory were for ponds with carbon dioxide bubbled through them. When consuming atmospheric carbon dioxide alone, algae are well able to befoul swimming pools, but their biomass output is much too low to make harvesting worthwhile. The visions of algae ponds stretching to the horizons of the world’s deserts and allowing the car industry to produce unfettered are chimerical.
Most of the development work on algal biofuels carried out to date has,
in fact, focused on recycling the emissions from fossil-fuelled power stations.
Some of the most sophisticated algal bioreactor equipment produced so far, by a
The scale of the investment required if fossil-fuelled power plants are to have their flue gases scrubbed by algae suggests that the technology will not be widely installed, just hinted at in coal-company handouts. A typical 1000-megawatt coal-fired power plant, it has been calculated, would require no less than 5200 hectares of algae ponds to consume 40 per cent of its carbon emissions.
None of this is to say that algal biofuels should not be developed and used. There are numerous industrial plants -- steelworks, cement works and breweries among them -- that release carbon dioxide and that might be connected to algal bioreactors, with useful emissions savings. Perhaps the most promising concept involves integrating algal biofuel production with stockraising and the production of electricity and biochar from biomass. Such complexes would use flue-gas carbon dioxide from biomass pyrolysis to enrich algae ponds, producing animal feed as well as algal oil. The fodder would be used to raise livestock, whose manure would be bio-digested to produce methane for additional process heat, electricity and carbon dioxide. The nutrient-rich sludge from the bio-digesters would then fertilise the algae ponds. In Arizona, the firm XL Renewables is developing a related concept that would feed 7500 dairy cows, deriving its carbon dioxide initially from the fermentation of corn for ethanol, and later from fermenting part of the algae output.
“Closed loop” algae complexes of this type have considerable promise for carbon abatement. Not only is their efficiency in offsetting fossil fuel use high (XL Renewables projects an eventual figure of 10 to 1 for its algal oil and ethanol), but their output of meat is achieved at a fraction of the emissions cost of conventional stockraising. In principle, they can allow grain to be used as human rather than animal food, and grazing land to be turned over to timber plantations or natural forest.
Perhaps the most impressive feature of these schemes is their potential to be expanded without incurring major environmental costs. Their basic requirements are for low-cost level land, sunlight, brackish groundwater (or seawater), mild-to-warm temperatures, and a source of carbon dioxide that does not give rise to additional fossil fuel use. The latter source need not be in plant form; with due care, selected urban garbage might be used in combination with a pyrolysis process. So too, conceivably, might sewage sludge.
This picture fits well with stretches of coastline relatively close to
various Australian cities. Areas such as the South Australian gulfs and the
Western Australian coast north of
But is there anything in the prospects for microalgal culture to suggest that on a world scale, it might replace all or most of current petroleum fuel use? With algae-cum-stockraising complexes the size of whole countries? Merely to pose the question is to answer it.
On a global scale, biofuels are unlikely ever to have more than “niche”
significance. Is the situation fundamentally different in
As scientist Mark Diesendorf observes in his book Greenhouse Solutions with Sustainable Energy, Australian landscapes with their warm temperatures and evergreen trees can be highly productive of biomass. Meanwhile, land area per head of population is unusually great. The effect is to make biofuels production, at least in principle, a more enticing proposition here than in most countries.
So far, investors have not been aggressive in developing this potential.
According to a study by the Australian Bureau of Agricultural and Resource
Economics (ABARE), biofuels early in 2009 were providing only about 0.5 per
This indifference has not been for lack of government backing. Ethanol
In NSW, and possibly in
Until now, most of the ethanol required for the 2 per cent mandate in
NSW has come from a plant at Bomaderry, south of
Over the full cycle of ethanol production and use -- that is, including the fossil fuels used in feedstock growing, transport and processing -- the E10 mandate is predicted by ABARE to result in no more than minor savings of carbon emissions. With the ethanol content of fuel at 10 per cent, the savings per kilometre are calculated at between 0.7 per cent (for ethanol from wheat) and 4.2 per cent (for ethanol produced from molasses, while using sugar refinery wastes to generate electricity).
There is no indication that when ABARE worked out these figures it factored in the most recent evidence concerning nitrous oxide emissions and crop fertilisers. Nor does it seem to have taken into account the effects of sharply cutting Australian supplies to world grain markets. As with US corn, the reduction in Australian grain exports will raise world prices and spur the destruction of forests for additional grain-growing in countries where controls on land clearing are weak or non-existent.
In mandating ethanol use, legislators in NSW have argued that they are
looking toward the advent in years to come of “second generation”
ethanol-from-cellulose processes, expected to sharply reduce the diversion of
food grains to biofuels production. But for most of the next decade, if not
longer, the net effect of the ethanol mandates will be to put large amounts of
extra greenhouse gases into the atmosphere. The world environment would be
better off if motorists in NSW and
For biodiesel in
At present, most biodiesel sold in
According to ABARE, biodiesel production throughout
The best options for expanding Australian biodiesel production
sustainably involve tree crops in the north of the country. In
An obvious species for such plantations is Jatropha curcas. The plant has long been established in northern
A better candidate than jatropha in many settings might be the honge
tree (Pongamia pinnata), which is native to regions from
With appropriate support and training, graziers might well agree to
switch from cattle-raising to running biodiesel plantations. In
In theory, plants such as jatropha and honge could be cultivated widely
Amid the vastness of northern
Honge trees take up to 15 years to yield at their full potential. If
biodiesel is to contribute to a swift reduction in
At least ten universities and government-funded research bodies around
It is not hard to imagine how production of algal oil might take place
in integrated fashion on an industrial scale. Low-value land would be used,
quite probably coastal samphire flats close to infrastructure. Production of
biochar from crop wastes or trees such as mallee would provide energy and a
portion of the carbon dioxide. Water would come from brackish aquifers or
sewage too saline to be reclaimed for irrigated agriculture. Quite likely, the
algae would be grown not in broad ponds but using the trough-form equipment
developed in the
The process would be remarkably self-sufficient; the major inputs, apart
from the crop wastes or other biomass, would be phosphorus fertilisers, trace
nutrients, and possibly stockfeed supplements. None of the technology employed
would be really novel, and much of it could be bought “off the shelf”. Given
the political will, large complexes of this type could be operating in
Significant research into cellulosic processes is now being mounted in
October 2007 saw the setting up at Queensland University of Technology
of the Syngenta Centre for Sugarcane Biofuel Development. As described by the Australian, the centre involved “a
collaboration between the
The quantities of sugarcane wastes available in
…it is possible that more than half of
’s liquid fuels could be supplied from about 10 million hectares of dedicated land. Australia
If we allow three million hectares for biodiesel production, this suggests that about 17 million hectares of biomass tree plantations would be needed to keep the country’s petrol-driven vehicles on the road.
According to the Australian National Resource Atlas, about 13 per cent
Producing enough petrol substitutes to allow “business as usual” on
If the goals motivating policy are not to keep petrol-engined vehicles on the road, but to reduce carbon emissions by as much as possible while providing Australians with transport, different strategies will be followed. The cellulosic feedstock will be pyrolysed to biochar, while heat released in the process will be used to produce electricity which, by the time the biochar is sequestered in soils, will be emissions-negative. Even if the electricity is then used to charge battery-driven private cars rather than to drive trams and trains, the emissions savings compared to taking the cellulosic-fuels route will still be substantial.
The research effort now going into producing cellulosic biofuels from bagasse poses particular dangers: if the process is shown to be profitable, pressures will mount for sugarcane to be grown specifically to feed the biofuel facilities. Sugarcane is a heavy consumer of water, which might otherwise be used to irrigate food crops. Cane growing also requires abundant use of nitrogen fertilisers, the nitrous oxide from which can cancel out most of the gains in terms of greenhouse emissions.
How might the appropriate choices surrounding biofuels in
Within this context, vigorous work should go into researching and developing algal biodiesel complexes. The same should occur in the case of oil-producing trees such as honge and jatropha. Mandates for biodiesel use should be introduced, and depending on research results, steadily expanded as feedstock becomes available. The use as feedstock of edible vegetable oil from crops such as canola or oil palm, however, should cease.
The fermenting of ethanol from molasses -- which otherwise would be used mainly as cattle feed -- might well continue. No further facilities, however, should be built to produce ethanol from grains, and the ethanol mandates should be repealed. Biochar pyrolysis, on the other hand, has genuine promise, and depending on further research, should be developed both as an adjunct to algal biodiesel production and because its own by-products include a useful bio-oil. If the prognoses for biochar remain favourable, plantations of tree crops on historically cleared grazing land should be fast-tracked. But the resulting biomass should not be used to produce cellulosic petrol substitutes in any major way. If produced at all, these fuels should be a heavily taxed self-indulgence of classic car buffs and miscellaneous petrol-heads.
That would be a rational way to proceed. But in current political
circumstances, events promise to unfold quite differently. As the present
economic crisis ends, demand for biofuels to meet mandated levels, in
Those prospects might seem cause for environmentalists to reject the whole concept of biofuels. But technologies should not be ruled out merely because capitalism in its search for profit uses them in perverse and destructive fashion.
The task before environmentalists is to assess new practices critically, on the basis of their genuine merits. Combined with this must be a readiness to campaign for rational choices in the interests of humanity and nature, whatever the pursuit of profits might dictate.