A solution to the difficult issue of harvesting algae for use as a biofuel has been developed using microbubble technology pioneered at the University of Sheffield in the UK.

The technique builds on previous research in which microbubbles were used to improve the way algae is cultivated, a press release explains.

Algae produce an oil which can be processed to create a useful biofuel. Biofuels, made from plant material, are considered an important alternative to fossil fuels and algae, in particular, has the potential to be a very efficient biofuel producer.

Until now, however, there has been no cost-effective method of harvesting and removing the water from the algae for it to be processed effectively.

Now, a team led by Professor Will Zimmerman in the Department of Chemical and Process Engineering at the University of Sheffield, believe they have solved the problem. They have developed an inexpensive way of producing microbubbles that can float algae particles to the surface of the water, making harvesting easier, and saving biofuel-producing companies time and money.

“The next step in the project is to develop a pilot plant to test the system at an industrial scale”

Microbubbles have been used for flotation before: water purification companies use the process to float out impurities, but it hasn’t been done in this context, partly because previous methods have been very expensive.

The system developed by Professor Zimmerman’s team uses up to 1000 times less energy to produce the microbubbles and, in addition, the cost of installing the Sheffield microbubble system is predicted to be much less than existing flotation systems.

The next step in the project is to develop a pilot plant to test the system at an industrial scale. Professor Zimmerman is already working with Tata Steel at their site in Scunthorpe using CO2 from their flue-gas stacks and plans to continue this partnership to test the new system.

Biofuels and gases

The need for energy diversification is well established – fossil fuels are depleting and the quest is on for the array of alternative energy sources that will comprise our future.

Biomass and biofuels represent one such route, and steady progress has been made in the development of the first and second generation biofuels that may begin life as either wheat, fruit pulp or even plant stems. Augmenting this could be a so-called ‘next generation’ biofuel derived from algae.

Unlike some first or second generation biofuels, harvesting algae wouldn’t be seasonal; it would be a continuous process that takes place throughout the year and ultimately provides a plentiful, if not prolific, source of energy.
Algae requires a combination of sunlight, water, carbon dioxide and other nutrients to grow, with comparably large production quantities per acre of land, therefore utilising less land and energy per volume of biofuel produced as an end product. Further still, fresh water is not a necessity – algae can grow in salt water or even treated waste water.

Once the algae is successfully produced, the next step is to harvest the bio-oil, before this bio-oil is then the subject of process chemistry and engineering in a refinery setting. From there, the end product is distributed to the pump and ready for fuelling.

What’s also interesting is an observation from an industrial gas mindset. With algae consuming rather than emitting carbon dioxide, perhaps a role will exist for the industrial gas community in the future? Further still, could there be a role to play in the development of production systems and equipments and any other aspects of the biofuel manufacturing chain?


Gasworld’s Green Issue

gasworld front cover April 2011

Biofuels, biogas, biotechnology and the ‘green’ agenda will be in focus in gasworld’s April magazine, the popular green edition.

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