- Purnima Jalihal, head of the energy and freshwater group at the National Institute of Ocean Technology, is currently coordinating the development of the maiden ocean energy-powered desalination plant, at Kavaratti island in Lakshadweep. The plant is presently powered by diesel.
- Jalihal believes that the development of both small-scale off-grid ocean energy systems and large-scale structures are important to meet clean energy targets.
- In conversation with Mongabay-India, Jalihal discusses the future of ocean energy systems in India, the cost-based challenges, environmental impacts of marine renewables and the socio-economic benefits for coastal communities with the development of ocean energy systems.
A seawater-powered lantern with an output in watts; a small hut powered by one to five kilowatts of ocean energy; or a town that could run on megawatts harnessed from the ocean: from watts to megawatts every iota of clean energy, including marine renewable energy, is important in India’s energy basket, says ocean energy scientist Purnima Jalihal.
Jalihal heads the Energy and Freshwater group at the National Institute of Ocean Technology (NIOT), Chennai, India, and leads the development of ocean energy devices and thermal desalination systems at her lab. Of the many ways in which ocean energy can be accessed is through ocean thermal energy conversion (OTEC), a technology that taps into the temperature differences (thermal gradients) between relatively warmer surface waters and deep cold waters of the ocean to generate baseload electricity and desalinate ocean water.
What is ocean energy?
Ocean energy is a form of renewable energy which can be harnessed with the power of waves, currents, tides, temperature gradients and salinity gradients. Compared to other renewable energy systems such as solar, wind and hydropower, the commercialisation of ocean energy has remained slow over the decades.
However, many countries are now developing technologies to tap the potential of the oceans and meet the renewable energy targets. India, a member country of the Ocean Energy Systems (OES), a technology collaboration programme from the International Energy Agency, is also working on both small-scale and large-scale projects in marine renewable energy. According to OES by 2050, ocean energy has the potential to have deployed over 300 gigawatt of installed capacity.
She’s co-ordinating the development of the maiden onshore OTEC-based desalination plant at Kavaratti island in the Lakshadweep archipelago in the Arabian Sea that can generate one lakh litres of drinking water per day. “Right now we are being seen as really knowledgeable with our (indigenous) expertise in OTEC and thermal desalination,” she summarises India’s inclusion into the Ocean Energy Systems, a worldwide, country-based organisation within the International Energy Agency’s Technology Collaboration Programme (OES-TCP).
Are ocean energy systems viable and worth the cost?
On the eve of a crucial meeting at India’s Ministry of Earth Sciences in New Delhi to solidify an Indo-US partnership on ocean energy development, Jalihal gets candid with Mongabay-India about the perceptions around the growth in ocean energy. While solar energy research and development (R&D) has evolved in three decades to transition from a tariff of Rs. 45 per unit to Rs. 2 per unit, ocean energy, the least advanced in the renewable energy mix, needs a push today so that 20 years down the road it becomes as viable as the solar and wind sector in India, she says.
“There’s always a talk on capital cost (of ocean energy). While the cost is certainly important, when you finally take it to the common man, when you’re doing the R&D, the first renewable plants are never going to be viable, and people tend to forget this over a period of time.”
“If you go back into literature about the evolution of solar it used to be actually Rs. 45/unit at the time when it started. After three decades, it has reached Rs. 2/unit after a huge amount of subsidy that has been given in the country. We should not be comparing a Rs. 25/ per unit ocean energy device,” she says.
According to a report by the International Renewable Energy Agency (IRENA), OTEC is still very much in the R&D phase and unlike tidal and wave energies the players are not commercial but mostly in research labs and universities.
“We need to give it (ocean energy) time for evolution as well. But if we don’t start today, even 20 years down the line, we’ll be still talking about working on ocean energy and trying to make it viable.”
Ocean energy R&D in India is a catch-22 situation. “Unless you do it, you won’t be able to get there,” notes Jalihal, who did her Ph.D. in civil engineering from Duke University, USA, in 1994.
“You compare it with solar of three decades ago. Then it will make sense to you – how long the evolution of a renewable energy into a commercially viable product can take and how much effort it needs,” says Jalihal, recollecting the time spent on boats to deploy the pipeline for setting-up desalination plants in Lakshadweep islands in 2005.
OTEC-based desalination and coastal communities
Three of India’s land-based desalination plants based on Low Temperature Thermal Desalination or LTTD technology are in operation on Lakshadweep islands with an individual capacity of churning out one lakh litre of potable water per day.
It takes advantage of the required temperature difference of about 15 degrees Celsius between sea surface water and deep-sea water available along the archipelago. LTTD uses ocean thermal gradients but at slightly shallower depths (about 500 meters or 300 metres) to produce drinking water. Six more such plants are going to come up in the island group with a capacity of generating 1.5 lakhs litres per day.
Ocean energy technologies for India have to be environmentally-friendly and simple to operate. “They’ve very few components and they don’t need very great maintenance. So, the local communities feel they can do it themselves,” she tells of the success of the LTTD plants.
“So that’s why the world thinks that if they (India) can handle thermal desalination so well for two decades, they should be able to do OTEC as well,” Jalihal says, circling back to how the world views India’s developing prowess in its ocean energy mix.
Currently the LTTD plants are driven by diesel, which produces many harmful emissions when burnt. And that is where OTEC comes in.
“We are in the thick of it (developing OTEC-based desalination) right now. That will have an OTEC power generation which will power the pumps required for the desalination. We’re not promising additional power to the island but we will try to do diesel displacement in this – we will use the OTEC power to make the water; it should be a self-sufficient system where again, they will get clean water, but without using the diesel generators.”
Environmental impacts of marine renewables
With the ocean covering more than 70 percent of the Earth’s surface, scaling up marine renewable energy to reap climate benefits will also mean unpacking impacts of the energy development on the ocean environment.
“Environmental impact assessments for ocean energy (devices) specifically have not been done in India because we are still in infancy. However, the thermal desalination plants have had a lot of scrutiny. We are really yet to see any negative environmental impact of the wave and tidal energy devices because they are small demonstration devices so it is too early to tell. We will have to understand as we go along when we start scaling up into larger and larger megawatt ranges,” she says.
However, concerns on disturbance of seabed due to laying of ocean pipes linked to OTEC have also been raised.
A 2012 study by India’s National Council of Applied Economic Research, an economic policy research think tank, favours LTTD in Lakshadweep as the “best technology” for the coral islands, especially in comparison to Reverse Osmosis (RO), because LTTD doesn’t disturb the marine ecosystem since it doesn’t discharge brine solution into the sea, even though LTTD requires high energy use. LTTD also does not require skilled labour to keep it running.
The study works out the adverse environmental cost implications of adopting LTTD to 0.23 paise/litre. Cost of desalinating a litre of water on Kavaratti island stacks up to 77 paise if the project is to yield an economic IRR of 12 percent.
“If you take a holistic look at it and instead of just giving the carbon credits you put cost to the negative impacts generated by the technology, these seemingly expensive technologies today are probably more viable,” Jalihal responds.
Powering the blue economy while generating jobs
Jalihal sees significant job prospects with the Deep Ocean Mission’s thrust on energy and freshwater from the ocean to support India’s growth in the blue economy, particularly through off-shore energy development. “With such a huge platform being built in a shipyard and towed out and installed offshore with so much of complex process and components on board, it can lead to a huge set of jobs – several hundred jobs from the small skilled and unskilled labor all the way up to the actual engineers who make all these complex designs functional. So, any new ocean energy development when it is scaled up sufficiently is definitely going to generate a huge number of jobs,” she adds.
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Banner image: (Left) Purnima Jalihal, NIOT. Photo by Priyanka Shankar/Mongabay. (Right) A wave-powered navigational buoy. Photo from NIOT.