"When the ship needs maximum power—for example during casting-off and coming aside manoeuvres—the batteries supply the energy back to the engine."

A good development but the item is written by someone with no boat handling experience. No ship or boat needs or uses "maximum power" for docking maneuvers, i.e., coming alongside or casting off from a dock. Any experienced ship handler would typically use one-quarter or one-half power for docking and undocking. Ship power requirements go up exponentially with speed. Maximum power is only needed to achieve top speed, i.e., cruising at full speed with the "throttles wide open".

I'm getting pretty sick of the "zero emissions" terminology used to greenwash hydrogen-based propulsion systems. Nobody anywhere is actually producing significant amounts of hydrogen solely from renewable sources. Doing so would be far too expensive, even at today's prices for fossil fuels.

In the real world, the production of hydrogen is invariably associated with large quantities of CO2 if based on fossil fuels or else, of relatively large quantities of nuclear waste that no-one anywhere is prepared to permanently store in their back yard. Emissions of a different type and somewhere else are still not zero.

If anyone is worried about *exhaust* emissions (sulfur dioxide, NOx and PM10) close to shore, they should force ships to cold-iron while docked and, require the use of modern clean diesel technology plus low-sulfur fuel grades. Alternatively, they could demand a switch to natural gas fuel for (highly boosted) spark ignition engines in favor of diesel. CARB is currently pushing for similar changes in California ports.

In some cases, it might be possible to equip river boats with purely electric propulsion, e.g. by installing an overhead line and pantographs (retractable pick-ups otherwise used for trains). The water would serve as electrical ground. The vessels would probably have to feature lateral thrusters and computers to control their heading with great precision - they would have to maintain contact with the overhead line and avoid crashing into any of its supporting pylons at all times. In addition, protocols for connecting and disconnecting from the line and paying for the electricity would be required. The infrastructure required would be expensive but possibly still cheaper than using hydrogen.

That gas is far too valuable to waste on propelling vehicle on land or in the water. Other than in the pharmaceutical and specialty chemicals industries, it is best used for removing sulfur from sour crude feedstocks, to crack heavy oils and/or to increase the yields of BTL processes.

@ Biobanker -

ships plying river routes do need to use significant amounts of power to counteract the force of the current as they dock and undock from shore. Not the full rated power of all available engines, though, you're quite right about that.

"Posted by: Karl-Uwe Strunzen | Jan 4, 2008 6:41:34 PM

I'm getting pretty sick of the "zero emissions" terminology used to greenwash hydrogen-based propulsion systems. Nobody anywhere is actually producing significant amounts of hydrogen solely from renewable sources. Doing so would be far too expensive, even at today's prices for fossil fuels."

The point is, eventually there will be hydrogen produced from renewables such as solar. There are articles on this board about direct conversion of hydrogen from water using solar. One company has even picked up millions in investment capitol. It's just a matter of time.