1. Why is there a need for biofuels?
The transportation and energy sectors are the major anthropogenic sources, responsible in European Union (EU) for more than 20% and 60% of greenhouse gas (GHG) emissions, respectively.
Apart from contributing to global warming, CO2 has other several impacts on the environment and the life on earth. As approximately one third of the CO2 in the atmosphere is dissolved in the oceans, an increase of the CO2 emissions means a higher content of CO2 in the seawater, which translates into a more acidic pH. A significant variation on the pH would affect dramatically the marine biodiversity and would end up having implications for the whole life on earth.
As transport and energy sectors, strongly dependent on fossil fuels, account for a great part of the emissions, the introduction of biofuels can contribute significantly to the GHG emissions. This will not only boost the decarbonisation of transportation fuels, but will also increase the security of energy supply.
Harvested algae, like fossil fuel, releases CO2 when burnt but, unlike fossil fuel, the CO2 is taken out of the atmosphere by the growing of the microalgae or other biofuel source, so no extra CO2 is released if we consider the complete life of the process.
2. What are microalgae?
Microalgae are prokaryotic or eukaryotic photosynthetic microorganisms that can grow rapidly and live in harsh conditions due to their unicellular or simple multicellular structure. Examples of prokaryotic microorganisms are Cyanobacteria (Cyanophyceae ) and eukaryotic microalgae are for example Phaeodactylum and Nannochloropsis, which FUEL4ME project is using to produce biofuels.
Phaeodactylum is a marine diatom that can produce large amounts of oil. It has been shown to be a good candidate for outdoor growth and production of the polyunsaturated fatty acid EPA (eicosapentaenoic acid) Moreover, the full genome and transcriptome are published.3
Nannochloropsis is a marine eustigmatophyte, capable of producing high amounts of lipids (a.o. polyunsaturated fatty acids (PUFAs)).4 It is currently used as energy-rich feed for aquaculture and receiving more and more attention for the production of biofuels.
Microalgae are present in all existing earth ecosystems, not just aquatic but also terrestrial, representing a big variety of species living in a wide range of environmental conditions. It is estimated that more than 50,000 species exist, but only a limited number, of around 30,000, have been studied and analyzed.
3. Why are microalgae attractive to produce biofuels?
Microalgae produce very energy-rich molecules as they are photosynthetic organisms and they can live in many aqueous environments, such as saline or seawater, which gives them a low water footprint.
Although they are not superior to higher plants concerning photosynthetic efficiency, microalgae do have higher growth rates (as they do not have roots, leaves, stems) and they provide much higher oil yields than higher plants such as palm, soybean or rapeseed oil. Besides, they do not produce lignocelluloses, which release toxic gases when being burnt.
A fundamental advantage of biofuel production from microalgae is they don’t compete with agricultural feed products for the cultivable land, which would lead to a shortage of available arable land and to a price increase of agricultural products. For example, to fulfill a 10% target in EU from domestic biofuel production, the actual feedstocks supply is not enough to meet the current demand and the land requirements for biofuels production, would be more than the potential available arable land for bio-energy crops.
4. What are the benefits of using algae fuel over conventional fuel?
Fuels from microalgae have several advantages over fossil fuels as well as over the first generation fuels produce from crops:
- Compared to other biofuels, most of them made from crops, algae grows much faster and contains much more energy per unit of weight.
- Microalgae produces 30-100 times more oil per acre than corn and soybeans
- Microalgae biofuel contains no sulfur and hence is non-toxic
- Microalgae biofuel is highly biodegradable
- Algae solves the food vs. fuel crisis.
- Microalgae fuel is carbon neutral, since the CO2 emitted when being burnt out was previously taken from the CO2 in the atmosphere.
5. Can the production of biofuel from microalgae serve other purposes, apart from the energetic one?
Biofuel production from microalgae can be used as a way both to contaminants from water and the atmosphere and also to deliver valuable by-products for other industries.
Microalgae are very efficient in using fertilizers and waste streams as nutrient source, using NH4+, NO3−, PO43− to grow, thereby removing these substances from the water and cleaning it.
Microalgae can also be used to remove CO2 from industrial flue gases by algae bio-fixation, reducing the GHG emissions of a company or process while producing biodiesel
Besides, other by-products may also be extracted from the biofuel production process, with valuable applications in different industrial sectors, including a large range of fine chemicals and bulk products, such as fats, polyunsaturated fatty acids, oil, natural dyes, sugars, pigments, antioxidants, high-value bioactive compounds.
6. Does biofuel from microalgae have any disadvantages?
The potential of microalgae is clear but the technology for producing biofuels from microalgae is still immature, which results into high prices for the biofuel.
In order to make microalgae as a source for biofuels competitive with fossil fuels, it is important to reduce operational costs and to achieve a positive energy balance, since currently the energy input is higher than energy output.
7. How is the biofuel produced?
Biofuel production from microalgae consists of different process
1. Biomass production
Currently, production of lipids from microalgae is a two-step process. First
the microalgae are grown in batch cultures and, when a certain biomass concentration is obtained, stress in the form of nitrogen limitation is applied upon the algae to induce lipid accumulation. As a consequence the growth rate decreases resulting in low lipid productivity.
Within FUEL4ME, we will develop a one-step continuous process to enhance lipid productivity, which will result in a reduction of the operational costs and potentially an improved energy balance. After proof of concept within controlled indoor conditions, the continuous process will be tested outdoors under real production conditions in four different regions (The Netherlands, Spain, Italy and Israel) with different climates and two microalgae strains with different optimal growth temperature, using the photoreactors of the research facilities of the different project partners.
The conversion process consists of different steps: harvest, cell disruption, primary extraction, fractionation, conversion and hydrotreatment. For each step, the most promising technologies presently used in other industrial sectors will be applied to microalgal biomass, taking into account the criteria of low energy consumption and low operational costs.
Besides, a continuos conversion process is being design that uses all components of microalgal biomass: Besides the production of biofuel out of the low-value lipids, the high value lipids will be valorized to produce feed ingredients and other added value products. From the remaining biomass, hydrogen will be produced, which will be re-used in the conversion process of lipids into biofuels.
The following figure shows the improved process for biofuel production from microalgae being developed by FUEL4ME:
8. Which role plays FUEL4ME in the enhancement of biofuels from microalgae?
The overall aim of FUEL4ME is to establish a sustainable chain for continuous biofuel production using microalgae as a production platform, thereby making 2nd generation biofuels competitive alternatives to fossil fuels by:
1) Transforming the current 2-step process for algal biomass production into a continuous 1-step process with high lipid, which will result in a reduction of the operational costs and potentially an improved energy balance,
2) Development of a continuous downstream process using all components of the algal biomass
3) Integration of production and conversion process.
4) Reduce operational costs and improve the energy balance of the project
9. What will FUEL4ME lead to?
The main achievements of FUEL4ME are expected to be:
- Contribute to make microalgae a sustainable and viable feedstock for biofuel production from the low value lipids fraction
- Produce added value feed ingredients and chemicals from the high value lipid fraction
- Reuse the Hydrogen produced in the fractioning process for the algae-oil hydrotreatment process, making the whole process sustainable and improving the overall greenhouse balance significantly.