Catching the sun

by | 28th September 2016 | News

Home News Catching the sun

Ship & Boat International: Sept/Oct 2016

“With our solar-electric boats and ferries, we don’t see any reason why passenger water transport should run on diesel.” It’s a bold statement, but an increasingly common one, given the number of pure electric boat development projects in Europe and the US over the past five years, and the similar sentiments expressed by green ship pioneers in these territories. In Sandith Thandasherry’s case, however, we’re journeying to Cochin, on the south-west coast of India, where his company, NavAlt Solar & Electric Boats, is preparing to deliver the country’s first ever solar-powered ferry.

NavAlt was formed in 2013 as a three-way collaboration between Indian naval architect and builder Navgathi Marine Design & Construction, green tech developer AltEn Systems and hybrid-electric drive system designer EVE System – the latter two companies hailing from France. AltEn Systems has previous form when it comes to green craft development, having assembled  a series of solar-powered boats in its native land, dating back to the launch of a 10m x 3.5m passenger catamaran in La Rochelle in 1998. This experience was to prove highly beneficial to Thandasherry, CEO of both Navgathi and NavAlt, in his quest to realise a range of all-electric ferries.

It’s a good time to be a green craft developer in India. Authorities such as the Kerala State Water Transport Department (SWTD) are eager to invest in diesel-free transport solutions for the country’s backwaters – not just for the significant reduction in pollution risk, but because such solutions are economically viable. Thandasherry says: “Cochin University of Science and Technology [CUSAT] undertook a feasibility study and assessed a break-even period of six years for an electric ferry solution.”

Keen to secure all-electric passenger ferries for its territory, the Kerala SWTD issued a global tender for the construction of a first, demonstrator model. Following a stringent technical review, overseen by a panel comprising the SWTD, CUSAT, ANERT (the Government of Kerala’s organisation for renewable energy projects) and Kerala Ports, among other experts, NavAlt’s tender was accepted. Reflecting on this success, Thandasherry comments: “The customer support offered during the whole vessel life span, and the strong will to make the boating industry an eco-friendly one, make us different.”

Fast forward to September 2016, and India’s first solar ferry is complete. In October, the vessel will leave Navgathi’s Cochin facilities and undergo a series of sea trials. After training is completed in November, the fossil fuel-free newbuild will be formally handed over to the Kerala SWTD.

The ferry marries a GRP cataman hull to an aluminium superstructure, and features a length of 20m, a beam of 7m, a depth of 1.6m and a draught of 0.8m. The craft has the capacity to carry up to 75 passengers.

Pholtovoltaic panels, rated 20kW, are positioned on the ferry’s roof; “We chose these from among six suppliers who met the ANERT and Ministry of New and Renewable Energy [MNRE] guidelines,” Thandasherry recalls. These convert solar energy into electricity, to be stored within the vessel’s 50kWh lithium-ion (Li-ion) battery bank, comprising two 25kWh packs supplied by AltEn and EVE. The batteries then feed two 20kWh AC motors.

In sunny weather, NavAlt estimates that the ferry can expect a range of approximately 6 hours when travelling at a cruise speed of 5.5knots. Cloudier days could see this range limited to 4.5 hours, although secondary charging at the dock will remain an option. At night time, range decreases to 2.5 hours. Maximum speed has been calculated at 7.5knots.

Assessing the benefits
Obvious benefits include negligible risk of pollution, reduced noise levels and vibrations and freedom from the stink of petrol /diesel fumes. However, focusing on the cost element, and how this stacks up against that of a conventional, diesel-powered, steel ferry, reveals some interesting findings too.

For sure, there is a greater upfront investment for the solar ferry – approximately INR25,000,000 (US$373,000), compared to a spend of INR15,000,000 (US$223,000). However, in terms of running costs, NavAlt has calculated that the solar ferry will require an annual investment of just US$2,240, which contrasts extremely favourably to the US$44,790 which the average diesel ferry guzzles in a year. This could easily result in the Kerala SWTD realising a return on its investment in less than five years.

A diesel ferry will trump its solar equivalent in range; size for size, the average diesel tank will permit a range of 250km, compared to the solar ferry’s 85km. However, if one’s remit reflects short-hop services rather than lengthy coastal journeys, the drawbacks of solar ferries tend to end there. Other advantages include sub-60dB noise levels, in comparison to a typical diesel ferry’s 80-90dB range, and a sizeable saving in weight; from 45tonnes to 24tonnes at full load, when one swaps the diesel tanks for battery packs.

From an environmentalist’s point of view, though, a different set of figures make the solar ferry an enticing proposition. On an annual basis, the Kerala SWTD can expect to save 52,500litres of diesel and reduce local CO2 emissions by approximately 140-160tonnes.

Future plans
It is now NavAlt’s hope that this debut delivery serves as an apt demonstrator of these eco-friendly and cost benefits, to secure further orders for the team. “Other states, including Maharashtra, West Bengal and Uttar Pradesh, are eagerly looking forward to this launch, and to initiate their purchases,” Thandasherry says. “The Kerala SWTD has announced plans for nine passenger ferries this year. After testing, if our vessel lives up to expectations, most of these ferries will be solar-powered.”

NavAlt can also offer solar ferries in a range of sizes, to suit customer requirements. These range from a 30-pax catamaran – measuring 12m x 3.5m x 1.2m, drawing 0.6m and requiring 6kW worth of photovoltaic panels and twin 15kWh li-ion phosphate battery packs – to a 100-pax model, measuring 24m x 7m x 1.6m, reliant on a 24kW photovoltaic panel array, a pair of 40kWh battery packs and two 25kW AC motors. This 100-pax variant would enable a slightly increased range of 7 hours in sunny conditions and 5 hours in more overcast periods.

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