VENICE is renowned for its canals, gondolas, and its glamorous film festival. It is less well known for its green credentials. Yet the work of a team of scientists sifting through micro-algae on the neighbouring island of Pellestrina may change that. Researchers on this tiny, thin strip of land aim to power the city’s entire port by harnessing the bio-energy potential of algal life. They are busy identifying which of the lagoon’s native species of unicellular micro-algae can be bred in new bioreactors to provide efficient biomass for electricity and motor fuel production.
Set to be operational by the end of the year, the experimental tanks will generate 500KW of peak capacity with oil derived from algal pulp. If successful, the project can be rapidly scaled up to 50MW. The entire port currently consumes 7MW. It is one of a growing number of projects across Europe extracting bio-fuel from algae. These simple organisms offer a slew of advantages. They can be harvested as often as once every three days, have higher oil content than alternative biological sources, and, since they can grown in tanks, they reduce the risk of ecosystem damage and do not pinch increasingly scarce arable land as other biomass crops do.
Then there is the technology’s apparent carbon neutrality. So far no full life-cycle energy assessment has been undertaken. But, goes the argument, since algae can absorb carbon dioxide, the process is probably sustainable.
Predictably, algal energy is enjoying plenty of political support. “The European Union believes in the algae project,” says Gabriella Chiellino, president of Enave, a public-private partnership which runs the Venice operation with cash from the EU. The British government, too, has earmarked biomass heat and electricity as key cost-effective renewable technologies for the next decade in its Renewables Roadmap.
Yet despite this, scientists do not agree on whether the process can actually generate any useful energy. To achieve the abundant algal growth necessary, a substantial amount of water, carbon dioxide and fertiliser are required. The cost of these, combined with the energy used in harvesting and drying the biomass, means that any net energy gain may be nugatory.
“At the moment it is not economically or environmentally viable,” says Dr Blanca Antizar-Ladislao, of the University of Edinburgh. Another problem is the space needed to produce energy on a mass scale, she says. To generate enough bio-fuel for all European transport, for example, an area the size of Portugal would be required. A sandbank off the coast of Venice is unlikely to suffice.
In the future, proponents hope, technological advances will make algal biomass more viable. Dr Antizar-Ladislao’s team admits that algal growth can be sustainably spurred by utilising waste from sewage treatment and factory chimneys to provide the nutrients and carbon dioxide required. The British government’s former chief scientist, Sir David King, recently declared that algal bio-diesel is a “real solution” to fossil-fuel dependence if only energy requirements of the production process can be renewably sourced. However, work by his team at Oxford University found that with today’s technology the fuel needs 2.5 times more energy to produce than conventional diesel. Like the surrounding lagoon, the future of Venice’s energy generation may be green, but it remains a distinctly murky shade.