Hybrid Engine Systems and Sustainability

A quick look through the MAN brochure shows component efficiencies which are consistent with what I remember hearing was possible for automotive electric propulsion systems a few years ago. (It should be noted that these efficiencies are considerably higher can be relatively expensive.) Electric drive itself is still less efficient and considerably more expensive than a good mechanical only drive system using shafts and gears so there needs to be other reasons for selecting electric drive. The MAN brochure does a good job of presenting some of those reasons for larger vessels and many may be applicable for a smaller vessel.

 

Indeed...DE is very good for larger vessels. But when comparing a like for like on smaller vessels (the propulsion package), DE is simply far too heavy to be effectively used.

 

Having received clarifications from the Catalina 30 owner, the propeller has max efficiency at cruising speed. The drop in systems efficiency is mainly due to the fact that the test has been done running on the batteries (without gen), so the more they draw on their AGM batteries, the less efficient they are (Peukert exponent).

 

You post an interesting topic for discussion and I will add my own comments at the end, but a little bit of spelling coaching is required, notably: WHETHER, not weather(!)

 

Breakthroughs are coming fast.

http://www.idigitaltimes.com/articl...nia-teen-eesha-khare-wins-intel-cellphone.htm
http://www.usc.edu/CSSF/History/2013/Projects/S0912.pdf

This will likely change efficiency of DE system charging for cars and boats in the near future.

 

Back on topic: Hybrid Engine sustainability.

Let's consider two typical cases : the occasional two weeks cruise, and the very occasional transatlantic passage.

15-days cruise:
Sailing: 24 hours
Motorsailing: 48 hours
Motoring: 12 hours
House load: 2500 Ah

With a conventional diesel engine:
Motorsailing 2.5 l/h x 48 h = 120 liters gazoil.
Motoring 5 l/h x 12 h = 60 liters.
House load half charged when motoring, the other half charged @40A with engine idle two hours a day 1l/h = 30 l.
Total : 120 + 60 + 30 = 210 liters gazoil.

With a diesel-electric engine (always motoring with generator on):
Motorsailing 0.5 l/h x 48 h = 24 liters gazoil.
Motoring 6 l/h x 12 h = 72 liters.
Sailing regeneration 24 h x 0.5 kW = 12 kWh saved on house load.
House load 30 kWh x 80% gen. eff. = 37 kWh - 12 = 25 kWh x 0.3 l/kWh = 8 liters.
Total : 24 + 72 + 8 = 104 liters gazoil.

Ocean passage:
Sailing: 600 h
House load: 250 Ah x 25 days = 6250 Ah

With a conventional diesel engine:
House load charged with engine idle @50A three hours a day 1l/h = 75 liters.
Total: 75 liters gazoil.

With a diesel-electric generator:
Sailing regeneration is largely enough to cover the 3kWh daily need.
Total: 0 liters gazoil.

 

What size boat is this?
Reason I ask, is because lets find out what the battery bank would consist of to power it the way you have above...

 

Excuse me, I've just returned to this thread, as alternative propulsion systems are an area of expertise I wish to improve my knowledge upon. I understand the electrical theory and mechanics. I am assuming by DE system you are meaning a diesel to generator to DC motor propulsion system[?]. I am unsure of what you mean by 'sailing regeneration', is that the prop 'feathering' creating emf back to the batteries or just the DE running without connection to the propulsion motor?

 

This is considering you are not adding a battery pack for motoring! The electric motors are directly powered by the generator. On the sole number of charge/discharge cycles (400 to 1000?) and Peukert coefs., motoring on batteries is -for the time being- an absurdity.

This is a very quick and gross estimation, taking consumptions for conventional diesel from cruises I use to do on a 40ft monohull. Indeed subject to discussion and refinement, this is just to show that there is really no point comparing conventional and DE systems on the sole criteria of fuel efficiency. Motoring at cruising speed does not reflect the majority of consumptions for an average sailboat owner.

The result would be different if you have a conventional engine plus a generator on board, but then the DE system becomes challenging in terms of weight and cost -again without any DE battery pack.

 

I am converting a Magnum hull into a sport fish with Hybrid propulsion.

This will consist of twin diesel MAN V10 820hp with two 24kw electric motors coupled to the existing zf transmission and drive shaft with a 35kw-72v lithium battery bank.

It will also have a jet thruster for bow and stern all coupled to a joystick control system.

We will also be installing 6-345w solar panels on the t-top to produce up to 10kw every day.

The end goal of the project is to be able to propel the yacht up to 8 knots for trolling as well being able to travel and maneuver at slow speeds for a few hours at a time. The other advantages will be to create a great number of redundancies within the power and propulsion system.

Financial and environmental benefits will long term be a big factor.

I will give you one real world application so you can appreciate the benefits.

Leave River bend marina(the boats current location)use joystick control to maneuver out of tight spot under only electric power,travel down the river wait for bridge using GPS holding system (to stay in one spot without drifting)continue on down the river to bar cut at the exit from the new river(so far all under electric propulsion stored from the solar panel production at 5 to 8 knots for around 45 mins to 1h)exit bar cut to enter the ocean start the diesel main engines then switch electric to boost mode and accelerate using electric and diesel power for around 10 seconds until the boat gets up on plane then pull the electric motors back to neutral. At this point we are doing around 30 knots heading to Bimini in the Bahamas under diesel power,(the electric motors now become powerful battery chargers up to 25kw per hour being returned to the 35kw-72v battery bank)arrive in Bimini after around 90 mins,(45 nm)come down to 5 knots and move the electric motor controls to forward position and turn Diesel engines off and commence fishing under electric only continue pulling in fish for 2h at 5-8knots,(main battery bank will be low) start Diesel engines and continue fishing for 2h.(this rotation could continue as long as you would like switching seamlessly between electric and diesel propulsion) travel under electric across the shifting sands and down the channel to End of the World Bar and dock using the joystick control.(have enthusiastic conversations discussing the fish caught and all the bigger ones that got away!) No need for shore power,retire to your air-conditioned yacht and enjoy the silence(the 72v bank through an inverter will be supporting all the systems as well as backing up the 24v and 12v Batteries) Wake up after a very rested sleep and travel back out to start the fishing using the electric and diesel rotation every couple of hours. After another long day fishing head back under the Diesel engines back to Fort Lauderdale, come back down to 5knots and re-engage the electric motors and shut the diesels off, travel back down the river to the marina and dock once again using the joystick control. Switch the electric motors off and your epic, environmentally friendly,economical,stress free fishing trip has come to an end. The boat will continue to sustain itself using the 2kw solar system and the banks will be full again in 3 to 4 days with no additional power source.

During the 2 day trip we have been under electric power for an estimated 10h saving around 300 gallons of diesel or over $1,000.

In conclusion our intention is to push the boundaries of what is possible currently using ideas from a number of marine and automotive products while improving our enjoyment while reducing our cost and the impact on our environment.

 

Sounds interesting, but where does the energy come from to save 300 gallons of fuel?

6 off 345 W solar panels will, at best (even in that climate) generate about about 10 to 15 kWh per day.

Diesel has an energy density of around 46 MJ/kg, so 300 (US) gallons (945kg) holds around 43,470 MJ of energy, or about 12,075 kWh.

A poor diesel engine (maybe running at part load) will have an efficiency of around 30% (a good one would be over 40%). This means that 300 (US) gallons of diesel fuel will give around 3,622 kWh of usable energy from the engine.

Now let's look at the electric/solar charging system. Let's assume that you get an optimistic output from the panels (i.e. always sunny, never rains, panels kept clean and cool) and you end up with 15 kWh per day from them. Over 3 to 4 days you can generate between 45 and 60 kWh absolute maximum. This is equivalent to less than 5 (US) gallons of diesel burnt in a poor diesel engine.

Your battery has a maximum capacity of 35 kWh (I assume, that the "kW" is a typo). Because battery life will be very short if all of the capacity is used, the usable capacity will be at best 70% of this, and if you want to pack to last a few years it would be better to run it at around 50% SOC differential (lithium battery packs have a much reduced cycle life when allowed to charge above about 95% SOC or discharge below about 20% SOC). Your usable battery bank capacity is therefore around 25 kWh, or in diesel terms, about the same as 2 (US) gallons burnt in a fairly poor efficiency diesel engine.

Sorry, but your sums are way, way off here. At best you might save around 5 (US) gallons of diesel over 3 to 4 days, for a pretty big investment in solar panels, lithium batteries etc.

The idea of using an auxiliary electric drive for quiet, pollution free, low speed motoring is a good one, but there isn't a good financial reason to go down the hybrid route you're suggesting.

If you want a low power electric drive then it's far more cost effective to forget about the expensive battery bank (that will, at best, last for maybe 5 to 8 years before needing replacement) and go for a small, quiet gen set coupled to a smaller house battery bank and use that to drive the electric drive. You can supplement it with solar panels for a bit of "eco bling" but the reality is that the solar panels won't make a significant contribution to the overall energy use. The small gen set will save a bit of diesel over running the main engines at low power, and would also give redundancy in the form of a low speed "limp home" propulsion system if the main engines failed.

 

Probably could save 5 gallons just by reducing weight tearing out all the hybrid stuff.

 

After reading this and other threads that dismiss the feasibility or at least the practicality of solar electric sail or diesel hybrids I was concerned that I had my numbers wrong and that the solar electric sail hybrid I am planning is a no go.
For a reality check I installed on my own boat, which is currently on the hard undergoing a minor refit, four 100 watt flexible solar panels from China that with controller and wiring weigh altogether about 20lbs.The whole package cost less than $2000.00. For the past two weeks which have been overcast or raining for at least half the time, , sans shore power I have been staying on the boat with all the comforts of home, fridge separate freezer stereo micro wave lights etc. Every day by noon the batteries (my engine starter battery and my dingy battery, as my two very expensive AGM PT 1800 Oddessey 475 reserve minute batteries packed it in after two seasons) are back at 14.1 volts.
I usually spend my summers in Canada cruising Georgian bay and living on the hook, so it has been my practice to run a small 13 hp Kabota engine equipped with a 200 amp Balmar alternator to charge the house batteries rather than the main engine a Perkins 4-108 diesel also equipped with a 200 amp Balmar alternator. This saves fuel and the Kabota runs under adequate load. I have to run it twice a day for just under an hour and the batteries never get to 14.1 volts . This is I suspect the reason that I only get tops 250 cycles from the batteries. I burn over 20 gallons of diesel a month for house loads alone.
If the solar panels continue to operate as they are, I could remove the Kabota. it’s mounts, Balmar alternator, exhaust system, muffler, ect, and as well it looks like, reduce my battery capacity . If you include 20 gallons of fuel I would save At least 500 lbs in weight and still have all the power I need with reduced maintenance , no fuel bill for house loads and a reduced fuel bill for propulsion because of the weight savings. And then of course there is the “Green” thing.

 

But you're talking about almost a couple of magnitudes less energy than the post immediately preceding yours so of course it's going to work OK.

20 US gallons of diesel burnt in a reasonably efficient diesel engine is around 250 kWh, which is easily achievable over month with a modest solar panel array. In fact the small array that the previous poster was postulating would generate around 10 kWh per day, so 25 days would be enough to generate this modest amount of energy.

The point I was addressing as that you cannot save 300 US gallons worth of fuel over 4 days with such an array. Many folk seem to have an overly optimistic view of what you can realistically achieve using the current performance of PC panels.

 

I sell solar stuff. I use 20% as an actual figure.
For EG, if I have a 20 watt LED light that turns on at night, there will be at least 100 w of panels.
I don't think I've seen the light stay on till morning more than a couple times.

Solar panels are rated using 1000w / m2, and pointing directly at the sun.