[Australia] Next time you fly, ask the unsuspecting attendant if they happen to know how much carbon dioxide the aircraft will emit during the journey. Chances are you will be greeted by a blank stare.
Acutely aware of the contribution that jet travel makes to the enhanced greenhouse effect, and hence the ravage of climate change, airlines the world over are searching for greener, more renewable sources of energy.
Topping the list of contenders for tomorrow’s aviation biofuels are algae, the world’s fastest-growing photosynthetic organisms that can accumulate up to 80 per cent of their dry weight in oil.
This endows them with huge, as yet untapped, potential for global fuel production, says RMIT University algal and plant biotechnologist Aidyn Mouradov.
Delivering a keynote address at last week’s congress of the International Association for Plant Biotechnology in Melbourne, Professor Mouradov said that, by cultivating particular strains of algae, scientists can produce oils for specific purposes.
Various algae are grown in freshwater or marine environments. Their biomass can be doubled every eight to 12 hours – and they produce oil year round, unlike most seasonal crops.
Algae are more productive than other energy crops such as corn, soy or oil palm, Professor Mouradov explains.
“For example, algae can produce 10 times more than palm oil and require 10 times less land area,” he points out. This is important as biofuel crops have been criticised for occupying arable land that might otherwise be used to grow food.
Algae farming requires neither agricultural land – the micro-organisms can be grown on land too poor to use for traditional crops – nor clean freshwater.
“They thrive on saline, brackish and wastewater,” Professor Mouradov says, noting that they can be grown on excess nutrients in sewage wastewater. “This leads to a win-win situation with waste turned into an asset,” he explains.
Several experiments using algal oil for aircraft jet engines have been successful. EADS, the manufacturer of Airbus aircraft, recently completed a flight powered entirely by algae-based biofuel.
The company plans to test a biofuel-powered route – probably between Paris and Toulouse – within five years. By 2030, approximately 10 per cent of the Airbus fleet is likely to fly on a combination of pure or blended biofuels.
Other aviation companies and airlines are experimenting with a balanced blend of biofuel and fossil fuels – or with biofuel powering at least one of several jet engines. Qantas, for example, operated Australia’s first commercial flights powered by sustainable aviation fuel in April 2012.
The Sydney-Adelaide return service, using an Airbus A330, was powered by a biofuel derived from used cooking oil, split 50:50 with conventional jet fuel. Produced by SkyNRG, the fuel was certified for use in commercial aviation. Its “life cycle” carbon footprint was said to be about 60 per cent smaller than that of conventional jet fuel.
Elsewhere, a successful flight was conducted in Berlin at the International Aerospace Exhibition, using the twin-propeller DA42 aircraft.
The plane used less algal fuel per hour than it would have done if it had flown on conventional jet fuel based on kerosene. Measurements revealed that the aircraft’s exhaust contained lower emissions of hydrocarbons, nitrogen and sulphur.
“Algae have the potential to provide a renewable source of aviation fuel provided that it produces more energy than that used to produce it – and so long as its production cost is competitive compared with petroleum-based aviation fuel,” says Sydney University agronomist Daniel Tan.
Microalgae can play a significant role in reducing Australia’s dependence on imported liquid fuels, adds Monash University chemical engineer Sankar Bhattacharya.
“The main obstacle is unfavourable economics relative to the fossil-fuel-derived liquid fuels,” Professor Bhattacharya explains. “Research directed towards these problems will eventually bring the cost down, eventually on a par with fossil-derived liquid fuels.”
Bunker fuel used by ships is highly polluting. So any attempt to replace it with algal oil would benefit the environment.
With this in mind, Maersk, the world’s biggest shipping company, tested a mix of algal oil and bunker fuel on a ship sailing from Europe to India. The US Navy, meanwhile, has trialled algal fuel on a decommissioned destroyer. Both experiments seem to have been successful.
And, in a move greeted with caution by GM sceptics, US biotechnologist Craig Venter, who first sequenced the human genome, plans to genetically engineer algal fuel that could be grown and harvested in the oceans.
With voracious appetites for carbon dioxide, algae harness solar energy to convert the greenhouse gas into just about everything we need. As well as producing biofuels, these humble micro-organisms can contribute to a range of value-added products: healthy oils, pharmaceuticals, cosmetics, food supplements, pigments and biopolymers, to name a few.
To top it off, they make great bio-fertilisers. “These are getting very popular because they are eco-friendly and more cost-effective than chemical fertilisers,” Professor Mouradov adds.
Down on the farm
Like all bio-derived fuels, algae remove carbon dioxide from the air as they grow. So the ultimate fuel produced is carbon-neutral.
This is different to burning fossil fuels, where carbon that has been locked underground for millions of years is put back into the atmosphere. If the algae are used to make hydrogen, then it’s a double win – taking carbon dioxide out of the air and making a fuel that is carbon-free.
Algae are more versatile and adaptable than higher plants: they grow anywhere there is sunlight and water, Professor Mouradov points out. “Areas that are too dry, too hot, or too cold to support trees or other plants can still potentially be used for algae.”
Deserts and ocean areas are obvious places for algae farms, since the land cannot be used for much else and there is heaps of sunlight, he points out. The issue there is providing water and other nutrients – nitrogen, phosphorus, potassium and iron. But this is not difficult using a closed system where the water is trapped, and cannot evaporate.
Challenges for algal farming include the mechanics of harvesting the algae, in post-processing – for instance, converting natural algal oils into biodiesel – and the risk of virus contamination.
Some algae are toxic. For example, blue-green algae – a type of photosynthetic cyanobacteria, such as Anabaena – cause toxic algal blooms in rivers.
All the same, blue-green cyanobacteria make great nitrogen-rich fertilisers as they “fix” their own nitrogen from the environment. This means they can effectively make protein out of air. No higher plants are capable of this, with the exception of legumes.
With abundant sunlight and wide-open spaces, that are arid or semi-arid and so cannot be used for other forms of agriculture, Australia is ideally placed to farm algae.
Algae production facilities, at least to demonstration level, have been established in most states. Joint-venture Muradel, for example, is using smart technology to use marine microalgae for producing sustainable and renewable green crude, biofuel and biomass products.
The Western Australian start-up is developing Australia’s first fully integrated production plant for converting marine microalgae to green crude in Whyalla, South Australia.
Scaling up algae production for commercial use has been an issue since the early days of interest in algal production, says Susan Blackburn, the director of the Australian National Algae Culture Collection – a bank of more than 1000 strains of native microalgae with the potential for producing biodiesel, aviation fuel and a range of bio-products.
“The potential for animal feeds and fertilisers as bio-products with the developing algal industry is great,” Dr Blackburn says. “Even with the oil fraction removed for fuels, the remaining biomass is protein-rich and contains many other bioactive compounds.”
Microalgae, for example, are the fundamental marine source of the long-chain polyunsaturated omega-3 and omega-6 fatty acids. These are crucial for human health, as well as that of aquaculture animals.
Other high-value products include pigments, such as betacarotene and astaxanthin which are used in the human nutra-ceutical industry as well as for colouring feed. The so-called “super-food” Spirulina, meanwhile, is also a type of algae.
“Despite these examples, the potential of algal products is largely untapped,” Dr Blackburn says.
Photo caption: Airlines everywhere are looking for carbon-neutral fuels. Photo: Glenn Hunt
View original article at: Algae-based biofuels a sustainable way to fly