3rd generation biofuels: commercialization potential

Posted by Stella Kin

Great review paper on the commercialization potential of algae-based biofuels. I've picked out some of the information that we should consider. If we go down this route the paper will be a useful starting point.

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Renewable and Sustainable Energy Reviews 14 (2010) 2596–2610

Commercialization potential of microalgae for biofuels production

Costs associated with algae biofuels:

• algal biomass growth, harvesting i.e. isolation of the biomass from the culture, dewatering
  or concentration of algae for processing, and algal oil extraction systems.
• project costs e.g. engineering, permitting, infrastructure preparation, balance of plant, installation and
  integration, and contractor fees. 
• O&M costs e.g. expenses for nutrients (generally N-P-K), CO2 distribution, and water replenishment due to evaporative losses, utilities, components replacement, and labour costs. 
• costs of the land or leasing.

Recommendation: algae to biofuels plants may be effectively developed on land adjacent to power stations, for converting the CO2 from exhausts into fuel.

Why Algae?–advantages over first and second generation biomass feedstocks

• Microalgae can be produced all year round and therefore, quantity of oil production exceeds the yield of the best oilseed crops, see Table 1
• Exponential growth rates can double their biomass in periods as short as 3.5 h, oil content in the range of 20–50% dry weight of biomass
• In spite of their growth in aqueous media, the algae need less water than terrestrial crops thus the load on freshwater sources is also reduced
• Due to this reason, the microalgae can also be cultivated in brackish water on non-arable land, and therefore may not incur land use change, minimizing associated environmental impacts without compromising the production of food, fodder etc.
• 1 kg of dry algal biomass utilizes about 1.83 kg of CO2, thus the microalgae biomass production can help in bio-fixation of waste CO2.
• Dual potential for treatment of organic effluent from the agro-food industry for algae cultivation. Algae cultivation does not require herbicides or pesticides application
• Produce valuable co-products such as proteins and residual biomass after oil extraction, which may be used as feed or fertilizer, or fermented to produce bioethanol or biomethane
• The biochemical composition of the algal biomass can be mutated by varying growth conditions, and thus significantly boosting the oil yield.
• Photo-biological production of ‘bio-hydrogen’

Life-cycle analyses lack key stages in processing due to lack of data, e.g.

• non-availability of data from a suitable commercial plant as the commercial production of algae biofuels is yet in a budding state. 
• lack of data on the combustion of the bio-oils for energy generation. 
• non-consideration of biomass harvesting data.

Research is being done to cultivate the species with maximum lipid contents

In optimal conditions, 1 ton of wet algae biomass can yield about 200 l of oil

Growing

• The closed pond systems are similar to open ponds but are covered for cooler climates. 
• The open pond system requires constant 15 C temperatures, less maintenance, is less expensive to set-up but does produce lower yields. 
• Photobioreactors produce a higher yield per hectare, but have a higher startup cost as well as require engineered maintenance.

Algal bio-refineries to produce multiple products to maximise profits

Advantages of microalgae for biodiesel:

• Will not compete with the land and cereal crops. 
• High growth rate and provide lipids fraction for biodiesel production. 
• Microalgal lipids are mostly neutral lipids with lower degree of unsaturation. This makes microalgal lipids a potential replacement for fossil fuel.
• In spite of dependence of oil yield on the particular algal strain, the oil contents of microalgae are generally much higher than the other vegetable crops.

Production of bioethanol from algae. 

• Fermentation process involves less intake of energy and the process is much simple in comparison of biodiesel. 
• CO2 produced as by-product from fermentation process can be recycled as carbon sources for microalgae cultivation
• The technology for the commercial production of bioethanol from microalgae under development

Biogas / Biomethane

• Biogas produced from anaerobic microorganisms by anaerobic digestion
• Methane can be used as fuel gas and also be converted to generate electricity
• Encourage sustainable agricultural practices in providing greater efficiencies and reduce algae production costs. 
• Due to absence of lignin and lower cellulose, microalgae exhibit good process stability and high conversion efficiency for anaerobic digestion

What should be the ideal configuration of an algal biorefinery? Shall we go for a product-based or energy-oriented biorefinery? Or a hybrid?

Some market analysts feel that in spite of all the positive factors, e.g. fast growth potential, non-interference with food crops, CO2 sequestration etc., the successful commercial implementation of algal biofuel shall depend on the development of high-value co-products, e.g. renewable polymers or pigments. In view of this the pathway to algae biofuel commercialization is witnessing several breakthroughs and technological advances in synthetic biology, metabolic engineering and genomics; development of closed loop bioreactor systems and raceway ponds; harvesting, lighting and extraction systems.

Strategic steps for successful commercialization:

"fatter, faster, cheaper, easier and fractionation marketing approaches to help producers to reduce costs and accelerate the commercialization of algae biodiesel, biocrude, and drop-in fuels"

Lately, the Scottish government launched a £6 million EU project called BioMara

Companies

• Algae to Energy can extract algae oil from 0.08 up to $0.29 per gallon compared to other algae extraction methods ranging from $2 a gallon up to $12 per gallon.
• Harvesting technology from Algae Venture Systems -- costs less than $0.30 per gallon of oil harvested compared to traditional centrifuge technologies which can cost up to $1 or more per gallon. 
• Arizona State’s blue–green algae -- excrete a kerosene type of jet fuel 
• Algenol’s blue–green algae that excrete ethanol fuel directly. 
• There are also a few species of algae that will naturally excrete oils from the cells. By milking the algae, these algal micro-refineries help to bypass the harvesting, extraction and refining systems all together by excreting forms of biofuels directly from the cells. These methods have the capability to significantly reduce production costs, and help to simplify complex processes for emerging algae producers and customers of new algae biofuels production systems.

Reference

2010, Singh