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Algal biofuels seen as having potential, but much research still needed

Published at: Apr 23, 2010
source: Engineering News
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Is the large-scale production of algal biofuels a viable alternative and should South Africa be pursuing it as a liquid- fuels option? Proponents suggest that it could indeed be a viable endeavour, and estimate that an industry could emerge within five to ten years, or sooner, should there be an innovation breakthrough. They add that it could also form an important component of the country’s commitment to reducing its carbon emissions.

By: Jacqueline Holman

South Africa is a carbon dioxide- (CO2-) intense economy, with more than 75% of the country’s primary energy requirement sourced from fossil fuels.

For this reason, South African National Energy Research Institute (Saneri) senior manager Dr Thembakazi Mali argued that in a recent discussion on biofuels production in South Africa that the country has an urgent need to reduce fossil fuel dependence, reduce its carbon footprint and diversify its energy mix and supply.

One of the answers may lie in biofuel from algae, which is currently being researched and could form part of the country’s Industrial Policy Action Plan, where a Biofuels Draft Strategy has set a target for a biofuels market penetration of 4,5% by 2013.

The Council for Scientific and Industrial Research (CSIR) biosciences algal researchers Dheepak Maharajh and Rajesh Laloo state, in their 2008 research, ‘Indigenous algae: Potential factories for biodiesel production’, that fossil fuels are limited and are reaching exhaustion, which underpins the global search for renewable energy, including biofuels.

They state that microalgae are responsible for at least 50% of the photosynthetic bio- mass production on earth and are effective factories for different valuable products, such as vitamins, supplements, feeds and biofuels.

The International Energy Agency’s (IEA’s) ‘Bioenergy 2009 Annual Report’ also states that, in the longer term, aquatic biomass, or algae, could make a significant contri- bution to bioenergy. The report points out that future generations of biofuels, such as oils produced from algae, are at the applied research and development stage, and still require considerable development before they can become competitive contributors.

Characteristics of Algae
The potential of microalgae as an alternative and sustainable energy source has generated significant research and business interest in the past few years.

JSE-listed energy and chemicals group Sasol, which is the world’s coal-to-liquids leader, has flagged its interest in biofuels, and believes that microalgae have some advantages over other sources of biomass, owing to its ability to absorb CO2 at higher rates than terrestrial plants. This is directly linked to their rapid rates of growth, the ability to accumulate large quantities of oil that can be converted into a biodiesel product and the ability to be cultivated in arid regions where there is no competition with agricultural land. In other words, the food-versus-fuel debate is far less intense.

International consulting company Frost & Sullivan South Africa chemicals industry analyst Kholofelo Maele says that algal biofuels are part of a grouping of so-called “second- or third-generation biofuels” that can be used to produce ethanol or biodiesel and have the advantage of not using food feedstock.

Microalgae require sunlight, water and CO2 to grow. Under optimal conditions, algal cultures can double in population size between two and three times a day.

Maharajh explains that lipids and fatty acids form a significant part of an algal cell, as membrane components, metabolites and storage products. The profile of lipids can vary, but there are many organisms that researchers can select, such as those with a specific profile for use in the production of certain fuels and oils.

“Alga has the advantage that you can grow it on nonarable land, potentially using sea- water and brackish water, which are resources that would not be used for conventional agriculture,” says University of Cape Town (UCT) department of chemical engineering senior research officer Dr Rob van Hille.

Much Ground to Cover
That said, there is currently no company in the world ready to produce fuel from algae on a commercial scale. University of the Witwatersrand (Wits) natural science associate professor Vincent Gray says that there is still a lot of groundwork that has to be carried out before establishing a proven and working bioprocess.

Maharajh and Gray both believe that the first plant will probably be in production in about 5 to 10 years, but it could be sooner if some significant innovations take place. The rising oil price will promote ongoing research to make alternative technologies more feasible.

Research in South Africa is currently taking place primarily at universities, as well as at scientific and industrial organisations but the technologies are not yet adequately understood to determine whether algal biofuels will be commercially viable. Maele says that, globally, it is evident that research thus far has not been able to develop large-scale commercially viable technologies. The develop- ment of an efficient system for manufacturing fuel on a large scale is currently hindered by the cost of the available extraction methods.

Currently, Saneri, a government institute owned by the Department for Science and Technology and the Department of Energy, is funding academic algal biofuel research at Wits and UCT. A significant aim of Saneri is to accelerate second- generation biofuels, which include algae research.

UCT is currently carrying out research across a range of technologies and screening a number of algal strains in order to select those with high lipid content, potentially for producing biodiesel. The university is also working on a biorefinery concept, which is intended to work in much the same way as a traditional oil refinery. The biorefinery will have to generate value from everything in the process, not just from one product.

Van Hille explains that, from an algal perspective, the biorefinery will initially extract oil for biodiesel with potential to extract high-value speciality products at the same time. Then it will also look at value from the whole chain, including digesting the residual biomass, which has a high carbon content and intrinsic energy value, to make energy-rich biogas. Algae can be added to other fuel products for cocombustion or cogasification. Other products could include feed sources and bioethanol from cellulosic feedstock.

Meanwhile, Wits is carrying out generic prospecting on microalgae to discover which species are suitable for oil production and it will then develop bioprocess technologies to produce oil using these species of algae.

“We are firstly carrying out research on suitable algae, as not all algal organisms are suitable for biodiesel production. [The oil] has to have certain specifications to qualify as an appropriate oil from which transport biodiesel can be made, but, if an alga does not have these properties, it may be used to make heavy oil that can be burnt to [generate] electricity,” says Gray.

Further, the CSIR is also currently focusing on bioprospecting, or collecting, microalgae that produce lipids, from all South African environments and propagating the samples in a controlled environment. Maharajh says that, during 2010, the division will start to process some of these isolates and develop processes that will ultimately, hopefully, be imple- mented in industry to produce bio-oils.

He explains that this research includes investigating how certain algal organisms work and what can be done to increase their productivity. Eventually, the research will be scaled up to growing algae in small-scale ponds, which will lead to a pilot project of a 1-ha-size plant.

Commercial Research
Sasol, meanwhile, states that its investigation into the potential for the use of biomass as an alternative energy source includes the oppor- tunities for algae. Key issues that are being investigated include the return on energy invested, life cycle CO2 benefits, water and land requirements, as well as costs. The study is scheduled to be completed by mid-2010.

Sasol Technology is currently reviewing the potential and commercial prospects of algal biotechnology to convert CO2 to biomass and the conversion of this biomass to other energy sources, like hydrogen, methane and liquid fuels. It has contracted Rhodes University to provide detailed scientific and technical information on algal growth, while Sasol Technology research and development (R&D) is focusing on integration and engineering challenges.

Further, renewable-energy company Biogreen is also currently carrying out research on producing bioethanol and biofuels from algae.

The company has carried out microalgae tests on the use of lighting in raceway ponds. Biogreen MD and Southern African Biofuels Association board member Roy de Gouveia says that Biogreen is working with companies overseas on different lighting with different wavelengths that can be used to speed up the photosynthesis process.

He says that the recession dampened funding for the research and what was being called the “summer of algae” last season has flattened out, with a number of potential players disappearing. Biogreen does not have a large R&D budget for algal biofuels, but it does have an ongoing research division, as it believes that algae are the way to go.

De Gouveia says that all researchers are searching for the one strain of microalgae that will be the most efficient for producing bio-fuels, but he believes that the general consensus worldwide is that the most efficient process will most probably use a cocktail of algae. There are about five strains of algae that have been found to be quite powerful.

Van Hille agrees that if you are going to cultivate algae in an open pond, you are going to need to work with a mixed culture, as it will be impossible to maintain a pure culture.

Global Push
On a global scale, US multinational oil and gas corporation the Exxon Mobil Corporation announced its algal biofuels programme in alliance with genomic research company Synthetic Genomics (SGI), in July 2009, after several years of planning and study. The programme is a long-term investment focused on biofuel production from photosynthetic algae. If R&D milestones are met, it expects to spend more than $600-million on the project.

“If successful, these next-generation bio- fuels could augment the world’s transportation fuel supply and assist in reducing greenhouse-gas emission in the decades to come,” says ExxonMobil media relations adviser Cynthia Bergman White.

Ongoing ExxonMobil and SGI activities and challenges include identifying and developing algal strains that can achieve high bio-oil yields at lower costs and deter- mining the best production systems for growing algal strains, either in open photobioreactors, such as ponds, or closed tubular photobioreactors.

The alliance is also determining how to supply the large amounts of CO2 needed to grow algae and developing the large, integrated systems required for the full-scale economic production, upgrading and commercialisation of biofuels.

“If our efforts are successful, algae-based biofuels could help meet the world’s growing energy demand and help reduce emissions,” White says.

Harvesting Fuel
The process for algal biofuel production includes growing the algae in closed or open systems, harvesting the algae and extracting the oil.

The algal biofuel production strategy chosen will be dictated by the algal strain used. Van Hille points out that several of the strains that show potential for having high oil content for biofuels tend to grow in freshwater with a neutral pH, resulting in a significant potential for less favourable algae to also grow in an open pond, requiring different growth reactors to combat this.

He says that, if the process is carried out using closed photobioreactors, there will be more control over growth conditions and the process could potentially yield higher productivity, but the reactors are expensive and require more operational employees. Van Hille says that open ponds will be cheaper to build and operate, but could potentially lose out on productivity and the level of process control.

Harvesting algae consists of separating algae from the growing medium, and drying and processing them to obtain the desired product. The high water content of algae must be removed to enable harvesting by flocculation, microscreening or centrifugation.

Maharajh and Maele concur that extraction of oil is the biggest stumbling block for making algal biofuel technology commercial, profitable and viable, as the methods are relatively expensive. Maele explains that there are quite a few technologies that are being researched around improving extraction, which currently consist of two categories, mechanical or chemical extraction. Mechanical extraction is highly energy intensive and expensive, while chemical extraction has the challenge of disposing of the chemicals used in the process.

She adds that the only way to see which extraction technology is the best is to see how they develop, as most production is currently only in the pilot phase. Companies are also experimenting with enzymes to extract the oil, as the efficiency of the extraction process is a significant determinant of the commercial viability of algal biofuels production.

De Gouveia adds that harvesting is a challenge as there are no real engineering platforms to get the lipid oil out of the process quickly and efficiently at a suitable cost.

“Solid-liquid separation is a big techno- logical challenge that still needs to be suitably dealt with, so we are looking at energy efficient technologies for carrying out separation on a large scale,” says Van Hille.

Maharajh says that the entire process is relatively energy nonintensive, besides the extraction methods, but reports have shown that algae-to-fuel production is still energy positive, as it produces more energy than it uses.

Viability Factors
A factor that would make algal biofuels viable would be to look at the whole life cycle and use the by-products of the process, one of which is the leftover biomass, which contains protein and carbohydrates that can be used for ethanol production.

“If producers can reduce the cost of extraction and use the by-products, the whole process can be made viable,” says Maele.

Gray points out that only large companies will be able to fund such processes as a substantial investment will be needed. Such financial investments will only be deemed a worthwhile risk once all the research has been completed and proper costing has been determined, which is still a long way away.

“It is a tough call whether biofuel from alga is viable. I think it is an option that should be explored, but we should not bet on it solving all our problems,” says WWF trade and investment adviser Peet du Plooy.

On whether the process will create jobs, Van Hille comments that whether it is labour intensive will ultimately depend on the process used. Open-pond cultivation can, potentially, be less labour intensive than conventional agricultural products, but this will depend on the production strategy adopted.

Gray adds that producing fuel from algae could create jobs, as 100 000 bioreactors for each hectare of tubes will be needed in a plant and each will have to be checked and maintained, resulting in the need for maintenance labour. He says that employment will be created this way, as well as minimal labour in terms of the extraction process and operation of producing algae in a plant.

Africa’s Algae Potential
Areas in Africa, such as the Sahara Desert, the Kalahari Dessert and Namibia, are agri-culturally limited and, therefore, suitable for building algae biofuel plants consisting of 5-m-high bioreactors on scaffolding, says Gray.

“I would select remote marginal ground that is not used by anyone and is next to the sea to allow a plant to recycle the water back into the sea. Water is a big requirement and a huge amount of evaporation is required to drive the air through,” he says.

De Gouveia, Maele and Maharajh agree that South Africa is an optimum site for algal biofuels production, as Upington houses one of the only large-scale algae farms in the world, which produces beta carotene, or vitamin A. The country’s climate condition is suitable for these farms, as we have a fair amount of nonarable land that can be used for such plants, relatively moderate temperatures and the high solar radiation intensity needed for algae growth.

Van Hille says that, of the current third-generation biofuels technologies, algal bio- fuels have the most potential, especially in the South African context, as the climate and environment are conducive to large-scale growth.

Potential Benefits
ExxonMobil has concluded that biofuels from algae offer a number of benefits, including that algae can be grown using land and water unsustainable for plant or food production, unlike some other biofuel feedstocks. Further, select species of algae produce bio-oils through the natural process of photo- synthesis, which only requires sunlight, water and CO2.

Van Hille says that, in South Africa, there is a strong debate about food security and UCT is of the opinion that it is not necessarily a good idea to take agricultural food crops and convert them into energy crops when Africa faces a food scarcity.

“Alga has the advantage that you can grow it on nonarable land,” he says.

Another advantage is that growing algae consumes CO2, which provides greenhouse-gas mitigation benefits. White says that bio-oil produced by photosynthetic algae and the resultant biofuel will have molecular structures that are similar to the petroleum and refined products currently used.
Du Plooy adds that biofuels from algae is a good idea, as it is a sustainable and renewable resource. It has good energy economics and it could be a better choice of fuel than other biofuels, especially those that are also staple food sources, such as maize. Algae can also be used to clean up wastewater.

Further, a consultant on algae, who has worked with the US Department of Energy and the IEA, John Benemann, pointed out at the Seattle Microalgae Biomass Summit, in October 2008, that algae have the potential to yield greater volumes of biofuel for each acre of production than other biofuel sources and could yield more than 2 000 gallons of fuel an acre yearly, while yields for other fuel sources are far lower.

White adds that algae used to produce biofuels are highly productive and, as a result, large quantities of algae can be grown quickly and the process of testing different strains of algae for their fuel production potential can proceed more rapidly than for other crops with longer life cycles. Algae grow all year round and faster than conventional plants.

Environmental Effects
Maharajh says that, at this stage, the known environmental effects will only be positive, but a detailed environmental-impact assessment will need to be done before all the effects can be understood. Maele and De Gouveia agree on this and Maele says that any effects would be relatively small when compared with the potential benefits once the process is optimised.

Gray says that environmental effects will depend on the landscape as algal biofuel production has to be carried out on a large scale to be viable, and will take up many hectares and use white plastic to maximise light through the system. This may have an effect on the environment.

Maele says that algal biofuels will definitely be an answer to reliance on crude oil in the future, but it will be one of a number of renewable-energy solutions.

Gray warns that commercial-scale algal biofuel production will not materialise soon. There is also conflict in the arena of oil and nuclear lobbying, as there is still a huge vested interest in using fossil fuels, which are still viable and are needed, as there is currently no totally viable replacement fuel. White agrees that, in the years to come, oil and natural gas will continue supplying most of the world’s energy, as they are scalable, affordable and versatile. But alternatives and next-generation fuels could play important roles.

“The biggest danger around this technology is that there are people out there that make unrealistic claims which harm the reputation of real research. People need to be aware that the technology has been shown to be tech- nically feasible, but there are still areas that need research. We need alternatives to fossil fuels and this is one of the most promising alternatives, but expectations must be managed,” says Van Hille.

Meanwhile, Gray points out that the development of algal biofuels may be set back by the enthusiasm for the discovery of new natural gasfields in the US, the Gulf of Mexico and Alaska, as well as possible fuels off the coastline of China.

Alternatively, WWF still believes that South Africa’s answer remains to electrify transport, but Du Plooy says that, whether algal biofuels will be a real option in the future depends on their status of development and time.

He comments that it will be wonderful if algal biofuels can be produced, but there is concern that we do not have the time to develop such a technology and, by the time we do, it will be too late to combat the effects of climate change and oil scarcity in the future.

“In my opinion, fuel from algae is the only solution. The question around crude oil is mute. We have to find alternatives,” concludes Maharajh.

Edited by: Creamer Media Reporter

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