29 September 2020
All-gas - Algae biofuel: clean air, clean water - clear conscience

 

Spring 2020


To promote the technical feasibility of Algae Biofuels, the EU FP7 Energy programme launched in 2011 three projects on a demonstration scale. All-Gas is the only one of this cluster to produce algae and operate the entire value chain of biofuel conversion and fl eet demonstration. The integrated design of energy efficient wastewater treatment, based on high-rate algal ponds, allows to harvest nutrients, while producing biogas and reuse water without external energy input.

Full sustainability is reached based on a circular economy concept, avoiding dependency on fresh water, arable land and inorganic fertilizers. The Life Cycle Assessment (LCA) performed on the demonstration plant showed an energy return on investment (EROI) of 4, changing the paradigm of effluent treatment from energy consumer to net energy exporter.

The consortium www.all-gas.eu, led by Aqualia, demonstrated on large scale the sustainable production of biofuels based on low-cost microalgae cultures. 2 ha of raceway ponds and related flotation harvesting and thickening were operated over several years, with the biomass digested to biogas and upgraded to biomethane, which fueled 3 test vehicles that ran for 70,000km each over two years.

 

Previous to the implementation of the Demo phase in 2017, a stepwise scale up of the process was carefully designed and implemented in order to minimize risk. Pilot plants were installed in 2011. In 2014 the plant was scaled up to a 1,000m2 prototype and its respective work and testing program allowed to confirm key parameters. A biomass productivity with a yearly average above 100t/ha was achieved, and biomethane yield reached 200L CH4/kg VS. In May 2016 a first car validated the microalgae fuel quality produced in All-Gas project.

The biogas upgrading unit fueled a test fleet of 3 dedicated vehicles, as well as 4 other vehicles for municipal services. To evaluate the effect of the biomethane on engines, each test car was monitored over a 70,000km evaluation program. Over the duration of the project, All-Gas was able to move the fleet vehicles in Chiclana around 400,000km, which is equivalent to travel around the world 10 times.

 

The demo operation showed that each hectare of algae culture has a wastewater treatment capacity around 1,000m3/d, producing biomethane above 1,300kg CH4yr – enough to fuel 20 cars (at 4,5kg/100km and 15,000 km/yr). This represents four times more than what is achieved with conventional biofuels, such as bioethanol from sugarcane or biodiesel from palm oil, both yielding about 5,000L/ha/yr.

Additionally to renewable energy production, the circular economy concept of the all-gas project signifi cantly reduces the electricity required to treat wastewater. Compared to conventional processes, for each 1,000m3/d treated around 0.4kwhm3 can be saved - equivalent to the yearly electricity consumption of more than 20 people. Extraction of lipids was also demonstrated with BDI's RepCat process, producing a few liters of algae-biodiesel within the specifi cation of EN 14214 except for the sulphur content. Some of the results are included in the new documentary Brave Blue World.


Brave Blue World trailer