Microalgae: A potential fuel alternative in India?
By Viyona Mohan
With the ever increasing demand of energy, there is also an increasing awareness of the unsustainable usage of fossil fuels. In this context there has been a growing need to explore alternate forms of energy that are less harmful to the environment, specifically fuels that are carbon neutral. One such alternative has been biodiesel generated from feedstock, vegetable oil or animal stock. India has also invested in research and development of fuel produced from Jatropha plant under the National Biodiesel Mission (NBM). Despite this, the project of transitioning to biodiesel in India has been largely unsuccessful for a variety of reasons. In comparison, research on second generation fuel from microalgae has shown that it is more sustainable as it lacks the characteristics that had made plant based biodiesel unsuccessful.
What is Microalgae?
Microalgae are primitive photosynthetic organisms that are extremely small and have a very simple cellular structure. Because of their extremely small size, microalgae have a large surface area to volume ratio which allows them to take greater amounts of nutrients from water and convert greater amounts of solar energy as compared to high plants (Usher et al., 2014). They are capable of synthesizing large quantities of oil and grow at a very high rate in high stress environments. They can be cultivated in saline or non-arable land as well and also help in bioremediation of waste water.
The same quantity of microalgae can be used to produce a much larger amount of biodiesel as compared to other sources. Research has found that microalgae is the most promising source of biodiesel that will be able to meet the requirements of the transport sector (Khan et al., 2009). It is found that in comparison to all other forms of biodiesel, only microalgae has the capacity to completely replace conventional fossil fuel. Further, since it is a second generation biodiesel, it is not directly dependent on food stock for production. Another huge criticism of biodiesel has been that they would require large farmlands for production. Microalgae on the other hand can be harvested and biodiesel can be produced in tubes in the ocean. According to a paper by Khan et al, microalgae can produce 200 barrels of algal oil in about 200 hectares of land (Khan et al., 2009). This is found to be 100 times the amount of diesel that can be produced by rapeseed, sunflower, palm and soybean. Microalgae will not compete with agriculture and has the potential to produce much higher fuel per unit.
Potential in India
Owing to the huge population of the country, India’s food requirements are extremely high. Therefore, fuel production cannot compete with land for food production. It is found that in India 26 million hectares of land is used for the cultivation of oilseeds and the yield per hectare is found to be low (Milbrandt & Jarvis). Despite being the fourth largest producer of vegetable oil in the world, it is still imported due to the high consumption demand. Hence, vegetable oil as a source of biodiesel is not an option for India. The government, considering these limitations, invested in production of biodiesel through Jatropha. However, large scale production of Jatropha is difficult as farmers do not consider it profitable to grow the crop as the fruit shows up only three years. There is also a lack of existing seed collection and oil extraction infrastructure. In such a context microalgae is seen as the next best carbon neutral source of biodiesel. Currently there are three types of biodiesel plants that are being considered in India: open ponds, closed bioreactors and hybrid systems. The most popular option in terms of sustainability is a production system that makes use of waste water or any stationary CO2 source (Khan et al., 2009).
Milbrandt and Jarvis have conducted a detailed analysis of the scope of microalgae biodiesel production in India and found that the conditions in the country are overall favorable (Milbrandt & Jarvis, 2010). India has many stationary CO2 sources in the form of thermal power plants, cement plants, fertilizer plants, steep plants etc. All of these plants have the potential of being co-located alongside microalgae plants so that the CO2 can be recycled for the production of fuel. Besides this, India also produces a high amount of wastewater due to the population and agricultural activities. Since freshwater sources are limited in the country, wastewater microalgae plants are the only sustainable system that can be considered.
Another factor that must be considered regarding sustainability is the farming facilities should not be located in fertile agricultural lands (Milbrandt & Jarvis). Even though the space required to grow microalgae is far less compared to the space required to grow crops for first generation biodiesel, for greater sustainability microalgae should be produced only on waste land. Currently the extent of wasteland in the country is 18% of the total land area. If even 10% of this land is entirely dedicated for the production of microdiesel then it would produce approximately 22–55 Mt of algal oil which could replace 45%-100% of India’s current diesel consumption (Milbrandt & Jarvis). The study also conducted a site-suitability analysis for microalgae and found that the most suitable locations for the algae farms are in coastal locations in the southern and western parts of India. These locations are ideal as saline water and high sunlight ecosystems for the ideal growth of algae.
Challenges
The biggest support for the sustainability of microalgae fuel or any other form of biodiesel comes from its carbon neutral nature. However, carbon neutrality does not reduce its potential to harm the environment through other forms of emissions. Many of these emissions have a much greater global warming potential. Algae derived fuel results in the production of methane, a potent greenhouse gas, due to decomposition by anaerobic bacteria. N2O another greenhouse gas that is generated during microalgal biomass cultivation (Usher et al., 2014). Ammonia and biogenic sulphur are some other such emissions.
Besides this, microalgae also puts the marine ecosystem at risk due to its potential impacts on aquatic biodiversity (Usher et al., 2014). This is because microalgae production is nothing but a controlled form of eutrophication. Eutrophication or algal blooms pose a serious biodiversity risk due to the large amount of oxygen that gets consumed during decomposition of dead algae. In the event that there is a leak in the tubes that grow microalgae, it would put the entire marine ecosystem at risk of large scale eutrophication. Further, introduction of a different species of algae into a foreign ecosystem during such leaks may challenge the survival of native species.
Also, calculations that render biodiesels as carbon neutral usually only consider the carbon consumed during growth and carbon produced during combustion. The intermediate carbon released during transformation to fuel tends to be ignored. A true evaluation of carbon neutrality would be inclusive of processes involved in the entire life cycle of the product. Several LCA studies conducted across the globe at various sites have revealed that microalgae projects are, in many cases, not carbon neutral as the rate of sequestration by plants is lower than the rate at which it is released during combustion.
An LCA study conducted in India revealed that since the electricity mix of the country was dominated by thermal power plants the final carbon impact of the produced biodiesel was high (Thomassen et al., 2018). This is because the electricity usage during the drying and processing stage of the microalgae is very high and so, similar to the electric vehicle case, pollution is merely transferred to another source. Although there are many microalgae production models that suggest usage of biodiesel itself to run the system, the initial run of such projects will require conventional sourcing of electricity. Further, transport of equipment and fuel would also contribute to the final carbon budget. Hence, there is sufficient validity in the arguments that challenge the carbon neutrality of microalgae fuel.
Hence, in the current energy landscape of the country, where we are highly reliant on imports to meet our energy needs, microalgae biodiesel production and usage is a more sustainable option. Even if it isn’t completely carbon neutral, the overall environmental impact is far lesser than conventional fossil fuel. However, in my opinion the more deeper question is if we should target energy sustainability to meet demand as compared to reducing demand? Developing alternate forms of fuel do not reduce carbon in the atmosphere and they do not change the current consumption pattern. They merely compliment the high paced growth rate and development that nations wish to achieve. Sustainability in the long run would require a shift in the manner we view our current needs as well as the injustices that occur to fulfil them. Microalgae biodiesel may be able fulfil our current needs, but with the current pace of growth and development, would it be able to fulfil needs of the future? Hence, development of alternate fuels should be done alongside a shift in our understanding of development, growth and infrastructure.
