Energy stirs up a fond use for algae
First, the bad news; because of climate change and worsening water pollution, algae, the world's fastest-growing photosynthetic organisms, are proliferating worldwide. A few of these are of the toxic blue-green variety.
The good news is that some strains of algae can be converted into an alternative source of renewable energy that is commercially viable.
"Newly trialled native species provide real hope," said Dr Evan Stephens of Queensland University's Institute for Molecular Bioscience and manager of the Solar Biofuels Research Centre.
"There are roughly 350,000 species of algae - more than all higher plants - around the world," he said.
By isolating certain strains and then screening them against criteria for producing fuel, scientists could breed new and improved varieties.
"By new strains, we mean algae varieties that have not been previously isolated, characterised and identified for fuels," Stephens said.
Genetic engineering helped scientists determine traits that might improve yields and other qualities.
"But in most cases we can go back and rescreen libraries of isolates for these characteristics which are naturally occurring," he said.
Working with Germany's Bielefeld University and Karlsruhe Institute of Technology, the Australian scientists have identified fast-growing and hardy algae that could lead to cheaper and more efficiently produced biofuels.
Previous research concentrated on finding oil-rich algae.
"Usually these are not fast-growing and are tastier to predators - like microscopic scoops of ice-cream," he said.
The resultant bio-crude oil could be processed in existing petroleum oil refineries, with no need for additional infrastructure.
"This is important as new infrastructure is expensive," Stephens said.
"We can make the same things from bio-crude that we make from regular crude - namely petrol, diesel, aviation fuel and plastics."
A new frontier is in the biology and developing of new strains that grow stably, while exhibiting resistance to predators and temperature fluctuations.
Stephens and his team identified hundreds of native species of microscopic algae from freshwater and saltwater environments around Australia.
These were tested against thousands of environmental conditions in the laboratory, creating a shortlist of top performers.
The researchers were currently trialling the algae at a pilot processing plant at Pinjarra Hills, Queensland, which opened in April.
Traditionally, algae have been grown for health foods, aquaculture and waste-water treatment. In recent years, algae oil has become the focus of an emerging biofuel industry.
Its production was still expensive, however, and viable commercial production had not yet been achieved.
"While we know that we can produce algae oil that is even higher quality than standard petroleum sources, we are working to increase the efficiency of production with the ultimate aim being able to compete with fossil fuels dollar for dollar," Stephens said.
ALGAE IN PROFILE
Found anywhere from oceans, lakes and swamps to soils, rocks and icy mountain tops, algae harness solar energy to convert greenhouse gas into just about everything we need.
Algae accumulated up to 80 per cent of their dry weight in oil. Their biomass could double every eight to 12 hours, and they produced oil year-round, unlike most seasonal crops, said Aidyn Mouradov, a plant biotechnologist at RMIT University in Bundoora.
Algae were more productive, he said, than other energy crops such as corn, soy or oil palm.
"For example, algae can produce 10 times more than palm oil and require 10 times less land area."
This was important as biofuel crops have occupied valuable arable land that could 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, fresh water.
"They thrive on saline, brackish and waste waters," Associate Professor Mouradov said, noting that they could be grown on excess nutrients in sewage waste water.
"This leads to a win-win situation with a waste turned into an asset."
Finally, algae could produce a range of value-added products: Ethanol, hydrogen, pigments, biopolymers and food for animals and humans. To top it off, they made great bio-fertilisers.
"These are getting popular because they are eco-friendly and more cost-effective than chemical fertilisers," Mouradov said.
Bunker fuel used by ships was 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, recently tested a mix of algal oil and bunker fuel on a ship sailing from Europe to India. The US Navy, meanwhile, trialled algal fuel on a decommissioned destroyer. Both experiments proved successful.
Several experiments using algal oil for aircraft jet engines have also shown promise.
And, in a move greeted with caution by GM sceptics, US biotechnologist Craig Venter, who first sequenced the human genome, planned to genetically engineer algal fuel that could be grown and harvested in the oceans.
As with all bio-derived fuels, algae remove carbon dioxide from the air as they grow. So the fuel produced is carbon-neutral.
This was different to burning fossil fuels, where carbon that had been locked underground for millions of years was put back into the atmosphere. If algae were recruited to make hydrogen, then one was taking carbon dioxide out of the air, and making a fuel that was carbon-free.
Algae were more versatile and adaptable than higher plants; they could be grown anywhere there was sunlight and water. Areas that were too dry, too hot, or too cold to support trees or other plants could still potentially be used for algae.
Deserts were an obvious place for algae farms since the land can't be used for much else and there was abundant sunlight. The issue there was providing water and other nutrients - nitrogen, phosphorus, potassium and iron. But this was not difficult using a closed system where the water was trapped, and couldn't evaporate.
Challenges for algal farming include the mechanics of harvesting the algae, in post-processing - for instance, converting natural algal oils into biodiesel - and in the risk of virus contamination. All monocultures, whether plants, animals or algae, were unstable ecosystems, and were at higher risk of being wiped out by viral pathogens compared with complex multi-species ecosystems.
A variety of viruses were known to prey on algae; these could enter algae farms in water or by wind.
FACTS AND FIGURES
Commercial algae productivity currently benchmarks at about 70 tonnes of dried biomass per hectare per year, Stephens explained: ''Having said that, many species cannot achieve this.''
Sugarcane is one of Australia's most productive crops, and also achieved 70 tonnes per hectare per year, but these harvests were measured in wet weight (in other words, 80 per cent moisture).
So algae were about five times more productive than sugarcane.
''For sugarcane, much of the harvest is fibrous or woody biomass, compared to a relatively uniform and useable product when using algae,'' Stephens said.
Although crop farming was unlikely to improve any time soon, global research efforts were raising total algae production efficiency towards the 4 to 5 per cent mark.
''This could halve, or slightly better, the one per cent of Australian land needed to produce five times Australia's oil consumption,'' Stephens said.
Algae cannot compete with solar photovoltaic or solar thermal energy just in terms of energy conversion, but electricity only represents 20 per cent of global energy consumption so the need for renewable fuels was currently greater.
''No single biofuel system can completely replace the current massive amount of petroleum used, so a suite of different biofuel technologies will be required,'' Stephens said.
Sydney Morning Herald