The Jharsuguda power plant in Odisha generates 420 megawatts of much needed electricity. However, the plant uses coal and the amount of carbon dioxide emitted poses concerns.
Most existing methods to capture carbon dioxide have limitations and are expensive. A sustainable solution suggested is to use microalgae. Microalgae have ten times the ability of trees to capture carbon. But are microalgae economically attractive enough for power plants like the one in Jharsuguda?
P Balasubramanian and team from the National Institute of Technology Rourkela, Odisha, had created a biophysical model to predict microalgal sequestration of carbon dioxide. They tweaked their model to suit the conditions of the Jharsuguda power plant. They took into account the daily averaged climatological data of the location for 21 years to estimate algal pond temperature over time since temperature has an impact on algal growth. This helps predict the productivity of the algal biomass and, hence, carbon sequestration capacity.
This model, created in MATLAB, was based on two sub-models: one to evaluate algal pond temperature using solar energy balance and the other, to predict the productivity of the microalgae through growth kinetics. The question that remained was whether the productivity is adequate to be economically feasible.
So they did a techno-economic analysis, taking into account the cost of setting up the algal ponds and related equipment, as well as the cost of operations and maintenance. And they came to the conclusion that 298 algal ponds of one hectare each are adequate to sequester all the carbon dioxide produced by the power plant. And that it takes less than three years to recover the capital costs incurred.
‘Our biophysical model was built for the microalgae, Thalassiosira pseudonana. But it can easily be extended to other algal strains by adjusting the features,’ says Aly Nazimdhine, NIT Rourkela.
‘We assumed that the algae are only 50% efficient in fixing carbon dioxide, though studies have shown that the efficiency can be much more’, says Bunushree Behera, his colleague. ‘We estimated that microalgal carbon sequestration will help the industry to earn carbon credits of 52 million dollars per year’
‘We took into account the possibility of using the waste flue gases for improving the algal productivity. This converts waste to wealth concept providing economic and ecological benefits’, says Balasubramanian, the team leader.
In spite of these assumptions that bring down the calculated economic benefits, sequestering carbon using microalgae seems to be economically attractive for the Jharsuguda power plant.
More than 50% of the electricity generated in India comes from coal-based power plants. Setting up algal ponds on an experimental scale, around selected power plants, can help us assess this technology to reach zero net emission of carbon dioxide.
Cleaner Production, 221:587-597 (2019);
Nehru Memorial College, Puthanampatti, Thiruchippalli