The sight of algae suspended in seemingly putrid water, be it in an untended swimming pool or the edge of a lake, is sure to make one wince. But if this water is transferred to a beaker and used to extract oil, it is capable of running a car.
The microscopic form of algae, or microalgae, are rootless leafless plants living in water that are gaining importance worldwide as an upcoming biomass, which can be used to produce biodiesel, an environmentally friendly and renewable source of energy. Biodiesel can also be used to substitute non-renewable fossil fuels, whose reserves are fast depleting, thereby making them unsustainably expensive. Biodiesel is produced from any oil containing free fatty acids, such as vegetable seed oil, animal fat or microalgae lipid. But since vegetable oil and animal fat are expensive, microalgae is the increasingly preferred raw material for making this form of fuel. Algal oil is converted into biodiesel by mixing it with alcohol and a base catalyst during which glycerin is produced as a by-product.
Developing a focused programme to harness microalgae biodiesel can be extremely beneficial for a country like Pakistan, which consumes approximately eight million tonnes of diesel annually in transportation,the agricultural sector and various other industries. Even if 10% of the country’s annual diesel consumption is replaced with biodiesel, it will save an estimated $1 billion every year.
Autotrophic algae, which are capable of synthesising their own food from inorganic materials using light and producing oil as a by-product, can be cultivated on 350,000 acres of uncultivated tracts of marginal semi-arid land to make biodiesel production commercially viable in Pakistan. The country’s solar radiation (5.1-6.2 kilowatt hour/square metre/day) is also best suited for microalgae cultivation which optimally requires 4.52 kilowatt hour/square metre/day.
The use of microalgae biodiesel has several advantages over conventional diesel. For one, it is environmentally friendly, as the carbon dioxide emissions from the combustion of biodiesel are re-absorbed during photosynthesis by the same number of plants from where it was derived. In fact, biodiesel reduces net carbon dioxide emissions in the atmosphere by 78.5% as compared to that of conventional diesel fuel. It is easier to grow microalgae, since they grow faster than terrestrial crops and require a smaller tract of land for cultivation. Its oil yield is also higher compared to that of other oil-yielding vegetable crops (canola yields 1,190 litres/hectare every year while microalgae yields 136,900 litres/hectare per year). Additionally, microalgae can be used to treat waste water, whereby the tiny organisms consume nutrients such as nitrogen, potassium and phosphorus, before it can be disposed off safely.
The process of obtaining biodiesel
The microalgae are also quite versatile in their use. The by-product in the form of glycerin has a market value of $36/litre (Rs3,582/litre), and its prime consumers are pharmaceutical, cosmetic and soap industries. Similarly, carbohydrates worth $14.25/kg (Rs1,418/kg) and proteins worth $82/kg (Rs8,159/kg) found in microalgae are used in nutritional supplements. The microalgae cake left over in the process can be burnt to produce heat energy or methane gas that can be used for heating or cooking in households.
The species of microalgae native to Pakistan, however, has yet to be explored thoroughly. But as the cost of petroleum skyrockets and natural gas reserves continue to dwindle, it is worthwhile for the government to invest thought and money into this form of biodiesel.
• Price of oil is US$102/barrel (Rs10149/barrel).
• Pakistan’s diesel usage is eight million tonnes annually [equivalent to 28.28 million tons of oil]. This is 75% of the annual energy use.
• Targets set by the Alternative Energy Development Board of Pakistan:
— Replace 5% of the total diesel consumption with biodiesel by 2015.
— Replace 10% of the total diesel consumption with biodiesel by 2025.
• Biodiesel reduces net carbon dioxide emissions to the atmosphere by 78.5% as compared to conventional diesel fuel.
Mehmood Ali is a PhD research scholar at the Systems, Power and Energy Research Division, School of Engineering at the University of Glasgow, UK.
Published in The Express Tribune, Sunday Magazine, June 8th, 2014.