Hybrid Engine Systems and Sustainability

I would like to ask this forum about the quandary of sustainable and green design within the marine industry!

First of all, is this even possible?

How can a hybrid system, which normally has more transfers of energy in its system than conventional diesel engine to prop system conserve more energy? And how on earth can batteries which add weight and contain toxic chemicals ever be considered as sustainable?

I would like to seek the marine community's take on this and weather there are any key example of bad and good design when it comes to sustainability.

I look forward to hearing from you!

Kind Regards

Chris

 

There have been many discussions on this forum about hybrid propulsion, all you have to do is to perform a "search" function.

For example:
http://www.boatdesign.net/forums/hybrid/so-why-doesnt-work-34765.html (the title tells it all )
http://www.boatdesign.net/forums/powerboats/another-hybrid-success-43764.html
http://www.boatdesign.net/forums/hybrid/nanni-diesel-hybrid-propulsion-35546.html

Cheers

 

Hybrid systems in vehicles gain their efficiency by recovering what would normally be waste energy of braking, coasting down hills and killing the engine when the vehicle is stopped. None of these apply to boats. The only case where hybrid is applicable to boats is where a very efficient engine is run at its most efficient rate and the stored energy is used by an electric motor that runs as needed. Only boats that are in use a majority of the time can gain sufficient recovery of energy to offset the losses in the added complexity of the whole system.

A plug -in system gains additional efficiency by using some power from the less costly electric grid but boats are so draggy compared to vehicles that only great expensive battery banks can make this an option.

 

Hybrids work - at least the ones called motorsailors .

 

On a yacht most energy is burned with ships services....aircon, refer, electrics....

Any hybrid that handles this load with stored energy is worthwhile.

 

Jonr nailed it.

 

Yes the jonr statement is right on. The broadest conception of hybrid, implementing two separate energy sources, windpower and diesel energy, is what a motorsailer does well enough.
Hybrid cars, with traction batteries and motorgenerators and fuel engines, have harnessable energy opportunities: every stoplight, etc. A hybrid car on the road at a constant 70mph has constant work of pushing through air; the hybrid components are dormant then. The economics of mass production allows us to drive hybrids that capitalize on driving conventions: whenever the foot is off the gas, rolling energy is pulled into traction batteries.

A boat deals with even more viscous stuff, water. Most of the time a boat is expending large energies pushing water aside and behind. Rolling energy, momentum, is seldom there to be stored. Racing machines like VendeeGlobe boats tap small amounts of momentum (better stated:drive) to make/store electrical energy for auxiliary operations, but they do not begin to attempt to use that energy to move the boat through the water.

In the latest Professional Boatbuilder, Calder writes of "The Hybrid Conundrum" (April/May 2013). His examination/elucidation is detailed and insightful. But Chrisyk's initial question pertains to most most boaters here and now, and almost any auxiliary sailboat, judiciously driven, is indeed the best example of hybrid power in the broadest sense.

 

Hybrid in the sense of automobile technology is useless for a boat, sure.

But, I have always wondered why nobody has tinkered much with heat engine hybrids for boats.
Even the most fuel effecient diesels are 50% or under.
The rest of the energy is leaving as heat in the exhuast or cooling system.

So why can't we take a normal boat, and then have a small steam engine connected to the prop shaft with a clutch?
There could be a distilled water tank, and a pump would pressurize it towards the steam engine. On the way, the water would be pre-heated in a heat exchanger from the main engine from the cooling system.
From there, the already super hot water would travel through a heat exchanger using the main engine exhaust to bring it up to past boiling temperature. Now it could drive the pistons on the steam engine.
After exiting the steam engine, the steam could be cooled and condensed back to water using a heat exchanger and fresh water.
Now the condensed water could fall back into the tank of fresh water, ready to do the cycle again.

 

"On a yacht most energy is burned with ships services....aircon, refer, electrics....

Any hybrid that handles this load with stored energy is worthwhile."

"any auxiliary sailboat, judiciously driven, is indeed the best example of hybrid power"

Purpose designed solar powered electric auxiliary sailboat?

 

True electrics are just a pipe dream at the moment, though we're getting closer, the same decades old issues still exist, abet at slightly reduced rates. Energy storage advances are still some time off, in spite of recent movement. Each issue has seen some gains in recent years, but still not competitive with more conventional propulsion means.

To be honest, why bother, when sail is about as reliable and green as you can get. The term green, in the industry is a bit sill, considering what hulls are predominately made from, let alone propulsion systems. Real "green" is a log raft with palm leaves sewn into a sail. The real problem is folks want to compare green systems, with small block Chevy powered craft, which is just way outside the reasonable possibilities. If you get fair about it, an electric needs to reasonably stand up against a Con Tiki and even at this, they really don't have much of a chance.

 

Most of the "green" in boats is simple advertising hype.

As they used to say, " Boob Bait"

A charterer on a 40-60 meter boat loves to hear that he is saving the planet because a solar panel and battery operate the anchor light.

 

Hybrid systems only make sense where the ratio of peak power required to average power required is high. Cars are a good example, peak power is often ten times greater (or more) than average power (a typical saloon car runs at an average power of around 12 to 15hp, yet may well have 100 to 150hp available).

Boats run at a pretty low peak power to average power ratio, they may typically use about 50 to 70% of peak power as an average, may be more.

The hybrid system primary gain with cars is that it allows a smaller internal combustion engine to be used, running at a higher average power, and perhaps with features (like the Atkinson cycle Toyota use) that make the engine more fuel efficient but less flexible in terms of power delivery versus rpm.

Regeneration (recovering energy from braking) is only a tiny part of the saving for a hybrid car, less than around 8% of the total power used. The major gain is from allowing the electric motor to provide the high peak torque required for acceleration, so relieving the internal combustion engine of needing to work (pretty inefficiently) under these high load conditions,

 

I'll tell you what would be practical...
Battery powered cable ferry routes that are only crossing channels a few hundred meters.

It only takes those suckers like 5 minutes to cross, and they're docked most of the time.

 

But if you can have cables, you don't need batteries...

 

Good point.
Although I wonder what type of cables are designed to be dragged along a lake floor and also carry 600 + Volts