Technological innovations in micro-algae biodiesel should extend the scale of production by a factor of three, while at the same time reducing production costs by 90%, according to two researchers from Wageningen UR (University & Research Centre).
It should be possible to produce microscopically small algae in bulk in large-scale installations, with fertilisers (nitrogen and phosphates) from manure surpluses and wastewater and CO2 coming from industrial residues.
The micro-algae process could result in biodiesel and “an almost unlimited quantity of protein and oxygen”. The amount of fresh water consumed in algal cultivation is minimal because seawater can be used.
According to calculations on energy consumption in transport in Europe, almost 0.4 billion m3 biodiesel would be needed to replace all transport fuels. The cultivation of micro-algae requires 9.25 million hectares of land – equal to the surface area of Portugal – assuming a yield of 40,000 litres of biodiesel per hectare, to supply the European market.
Algae are more efficient at converting sunlight and fertilisers into usable oily substances than agricultural crops such as oilseed rape.
It is not necessary to have full sunshine for micro-algae cultivation, which is why it is possible to design reactors that look like vertical plates, on to which the light shines from one side. In this way, it is possible to produce 20-80,000 litres of oil per hectare. In comparison, one hectare of oilseed rape or oil palm yields only 1500 or 6000 litres, respectively, the researchers say.
Financial aspects
The 5000 tonnes of algae (dry matter) now produced annually in the whole world has a value of €250/kg. The price is so high because algae can make rare (and therefore expensive) substances like carotenoids and omega 3 fatty acids that are converted into high-quality products such as food supplements.
Palm oil used as fuel costs €0.50 /kg in comparison, but palm oil is and other fuel crops can be controversial.
A feasibility study into biodiesel from micro-algae showed that presently the cost price could be reduced to €4/kg. By making use of residues such as wastewater and CO2 from exhaust gases, by improving the technology and by shifting production to sunnier countries, it would even be possible to reduce the price of micro-algae biodiesel to one-tenth of that level, namely, €0.40 /kg.
However, the production of biodiesel from micro-algae would still not be financially viable. To achieve that goal, the whole algal biomass would have to be utilised. This consists of roughly 50% oil (€0.40/kg), 40% proteins (yielding €1.20/kg) and 10% sugars (€1/kg). This causes the value to rise to €1.65/kg which is enough to run micro-algae biodiesel production on a large scale.
Proteins
Algal proteins offer interesting possibilities. If all transport fuels were to be replaced by micro-algae biodiesel on a European scale, 0.3bn tonnes of protein would become available as well. That is 40 times more than the amount of protein in the soya that Europe imports each year. Thus, algae would allow the production of food and feed proteins as well as sufficient quantities of biodiesel.
With the aid of sunlight, algal growth requires 1.3bn tonnes of CO2 (Europe produces 4bn tonnes/year, mainly from fossil fuels) and 25m tonnes of nitrogen (wastewater and fertilisers contain 8m).
The research is presented by Professor René Wijffels and Dr Maria Barbosa of Wageningen UR in their article An Outlook on Microalgal Biofuels in Science.