As an example of a powerboat application, we are currently working with Independence Green Yachts (IGY) in the recreational trawler market. After carefully considering the use of batteries and solar power alone, IGY chose hydrogen as the best energy storage option for the weight and volume capabilities of a displacement vessel that typically sits in the sun more days than it runs. Plus, hydrogen is 100% clean, renewable, and readily available in water. IGY’s modern sixty foot trawler, called the Independence 60, was designed by a noted naval architect and is environmentally friendly from stem-to-stern.
The hydrogen storage onboard the Independence 60 will be equal to about 1,000kW of usable power. The vessel will be fitted with 75kW drive pods rated at 100hp each (these proven electric motors are currently used on ROVs for activities such as inspecting underwater cables or oil rig platforms). The maximum calculated speed of the I60 is 13 knots. At 6 knots, the I60 uses ~6kW of power, which can be provided by the solar panels alone (approximately 400 sq. ft.) on a sunny day. It will have 69Kg of stored hydrogen in metal hydride storage canisters that will take up about 90 cubic feet of space (providing ballast of approximately 12,000 lbs). The “no sun” range of the I60 using only hydrogen-fed fuel cells to produce electrical power is estimated at 1,200 NM at 6 knots (or 600 NM at 8 knots). There is an additional 100 NM range at 6 knots from the energy stored in the battery bank alone.
Trawler owners usually operate their vessel during the day, in not too windy conditions, and usually stop at marinas at night where they can purchase shore power if need be. Since they can achieve 6 knots from the direct sun, they can go at 8 – 10 knots and use very little of the energy stored as hydrogen for the 50-75 miles they travel in a typical day. (Their speeds are typically regulated by speed-limits in the waterways they use.) Any hydrogen energy consumed can be recharged using shore power at night or by the solar panels during daylight hours. For the typical owner, a week’s worth of sunshine will restore the hydrogen previously consumed for use the next weekend.