What's the point of hybrid power in a planing boat?

[ulyden]

The even older hybrid propulsion ship is the Normandie. Steem turbines and generators connected to eletric motors.

http://en.wikipedia.org/wiki/SS_Normandie

Hydrogen is expensive. Takes 2kwh energy to make 1kwh burnable hydrogen. Today 50-80 of all hydrogen is made from fossile fuels.

One reason for using hybrid power in a planing boat is to optimise the engine at high power by using a large turbo. This is lowering the fuel consumtion.

If the fuel consumtion is redused from 245g/kwh to 225g/kw due to better turbo efficiency you save 8% fuel. Thinking steyr 256hp engine this correspond to 4liters pr hour at full speed.

But the low end torque are missing and the boat is hard to get on the plane.
You have 2 110Ah batteries and fore one minute this can add on 2kwh/60min = 120kw. Teoretical. The power is limited by CCA capasity. If the batteries are 12V and the maximum amp is 800. Then the maximum power is 9.6kw each batteri or aprox 18kw ekstra. This you can put on where you need it most. So at 2500rpm where the power is 100kw so by adding 20kw you get a 20% increase in power at that point. But your batteri will be gone in 8min if you still dont get on the plane.

If you compare the Steyr M0256H45 and M0256H43 you see the point. Having more low end torque cost fuel in high end.

So in some cases it might be a idea. Volvo are using compressor for same purpose!

http://www.steyr-motors.com/products/pdf/MO256H45_FLC.pdf

http://www.steyr-motors.com/products/pdf/MO256K43_FLC_Neu.pdf

 

[westernman]

But the low end torque are missing and the boat is hard to get on the plane.

Electric motors have great low end torque.

Forget the hybrid bit, that is a waste of money, energy and resources.

But diesel electric (as in Intercity 125 trains, and some modern ships), or fuel cell (still relatively rare, although available to yachties for the house electricity) both make a lot of sense.

Hydrogen as a fuel will become common, when fossil fuel starts to run out. This is likely to happen in the next 20-50 years depending on the rate of new discoveries, China's rate of burning it, at what price level hydrogen becomes competitive, and how much land we are willing to sacrifice for making fuel as opposed to feeding the hungry (Biodiesel, ethanol etc).

Hydrogen can be made from excess electricity capacity (solar, wind, nuclear) when it cannot otherwise usefully be used.

 

[ulyden]

Electric motors have great low end torque.

Forget the hybrid bit, that is a waste of money, energy and resources.

.

It was the big turbo that gave the bad low end torque. The el motor could compensate by using the batteri power to add on 20KW in the low end area of the diesel.

The el motor could also provide a 3% maximum speed increase in 8 minutes.

If you are saving 5% fuel by having a better turbo this means that, depending on use, some money is saved.

 

[westernman]

It was the big turbo that gave the bad low end torque. The el motor could compensate by using the batteri power to add on 20KW in the low end area of the diesel.

The el motor could also provide a 3% maximum speed increase in 8 minutes.

If you are saving 5% fuel by having a better turbo this means that, depending on use, some money is saved.

You are better off using the diesel as a generator and directly using the electricity to drive an electric motor.
You then get your turbo diesel to run at optimum speed and you have all the torque you want. The whole set - diesel and generator can be easily set up to run at optimal speed.

Just leave out the battery bit - you are much better off without it (as is the QM2 and the Intercity 125).

 

[Assassin]

I am not missing the point at all, i am not quoting hypotheticals or terms such as theoretically because these are somewhat different to reality.

In real terms using such a system means your theoretical times are totally null and void unless you have some specialist batteries and very complex control systems for charging and discharging cycles, and power distribution. Drop an average battery below 10.5 volts and it is scrap, even the top range leisure batteries cannot go below 10 volts without being scrap, so effectively you are using less than 20% of the batteries capability or rated capacity.

This equates to considerable costs to move to hydrogen or other forms of gas to use as propulsion, so changing engines from diesel to petrol, and this additional hardware would equate to more then the cost of a new boat. You would need significant cost savings to recoup this expense, and an incredibly long life cycle and hydrogen or other gas systems provide this.

Lets look at an average top end control system for propulsion using electrical systems, the best are only 78% efficient, many much less, the remaining is just dissipated as heat, so even lower efficiency, costs; around £10,000.

Most of these theoretical equations have already been dismissed as pure tosh by working in real world conditions, and myself and other professional engineers simply laugh when we see them. We have seen, or see the real world results of these hybrid systems, and their numerous problems and vast expense. Why go to so much trouble and expense when you could equally use a hydraulic propulsion system, much cheaper and 98% efficiency.

 

[rafiki_]

I think there is a case for using battery power for propulsion on a large boat for low speed work in a Marina. The additional costs and weight are probably not a big issue for a 20+ metre boat, many of which do not go very far, but sit in Marina's.

For smaller planing boats, I think the additional weight of a the batteries, will be a significant impediment for getting over the hump, and I'm yet to be convinced that Lithium based batteried make sense in a boat, with the damp/humidity issues.

Hydrogen sounds great until you consider the storage issues. Best way to store hydrogen? using hydro carbons, like, gasoline, diesel or coal. Hydrogen storage tanks and seals are very problematical, smallest element, under very high pressure = problems. Think back to pictures of space craft about to be launched. All the vapour pouring out before the launch is hydrogen fuel.

Best hope for us boaties is renewable diesel fuel I'm afraid, but this is looking more promising as 3rd generation fuels are being developed.

Sorry, wearing a particularly heavy anorak this morning, sat in Incheon airport waiting for my connection to Nagoya, so this post is a bit rambling.

 

[westernman]

Why are big diesels more efficient than turbines?

Can someone explain why for electricity power stations and big ships that big diesel engines are more efficient than a turbine?

Presumably for aircraft, the equation for a turbine is different since the thrust generated for the weight of the engine is more important than outright fuel efficiency.

I think a some Navy ships are turbine powered - presumably for the same reasons as why turbines are used for aircraft.

 

[ulyden]

Large 2 stroke engines have a efficiency of 50%. Meedium speed engines
above 45% Gas turbines below 40%(single sycle). Efficiency on gas turbines is in heat rate. 8000KJ/KWH is 45% , 9000KJ/KWh is 40%. On diesel most suplyers gives sfc in g/kwh. So to compare you have to take the energy content in diesel fuel into account. So if you have 200g/kwh you have to multiply by 42900KJ/kg. So you end up with 8900kj/kwh that correspond to (3600KJ/KWH/8900KJ/KWH) 40.4 in shaft efficiancy. Medium speed engines uses 175g/kwh Large engines 165 g/kwh. That correspond to 50.8% shaft efficiency.

What these numbers are in BTU i don't have a clue!

To explain why its often the expansion ratio on the combusted air that gives the difference. In a diesel you can have higher pressure and temperature during combustion. You can se this on outlet temperature on the engines.Gas turbine engines often have 100 deg higher outlet temperature than diesels. On some powerplants this heat is used for steam production. Then the cycle efficiency can reach 55% on large gas turbines. This is complex and have a high cost. Not common on ships. Can be used on diesel engines aswell.

 

[Assassin]

You would not use diesel engines for power generation in a power station, you would use steam as it can be reused due to its expansion, and is the most cost efficient way of driving a turbine. Diesel engines are fine when you are away from mains power and want it.

 

[Latestarter1]

Large 2 stroke engines have a efficiency of 50%. Meedium speed engines
above 45% Gas turbines below 40%(single sycle). Efficiency on gas turbines is in heat rate. 8000KJ/KWH is 45% , 9000KJ/KWh is 40%. On diesel most suplyers gives sfc in g/kwh. So to compare you have to take the energy content in diesel fuel into account. So if you have 200g/kwh you have to multiply by 42900KJ/kg. So you end up with 8900kj/kwh that correspond to (3600KJ/KWH/8900KJ/KWH) 40.4 in shaft efficiancy. Medium speed engines uses 175g/kwh Large engines 165 g/kwh. That correspond to 50.8% shaft efficiency.

What these numbers are in BTU i don't have a clue!

To explain why its often the expansion ratio on the combusted air that gives the difference. In a diesel you can have higher pressure and temperature during combustion. You can se this on outlet temperature on the engines.Gas turbine engines often have 100 deg higher outlet temperature than diesels. On some powerplants this heat is used for steam production. Then the cycle efficiency can reach 55% on large gas turbines. This is complex and have a high cost. Not common on ships. Can be used on diesel engines aswell.

Ulyden thank you for your comments regarding BTU (British Thermal Units) remember we owned most of the world not so long ago!

As originally a low speed engine man, (Doxford Sulzer) then a high speed diesel man you fill in a chunk of understanding regarding medium speed diesel engines as well a gas turbines, thank you. Seems that our justification for using warship gas turbines is all about power density and ease of maintainence, removes the need for long periods out of commission for fuel rod replacement in the reactor core.

Going back to steam turbo electric aka Normandie/Canberra, actually and Americam concept for major warships dating from the 1920's. Without addition of battery power I cannot consider this hybrid.

Moving on to Hydrogen power. University of London is THE recognised organisation for providing energy carbon auditing throughout the world, and their view is clear: in terms of current and FORSEEABLE production technology Hydrogen production is a gross emitter of CO2, which does includes current staus of blue sky stuff such rust rich solar cell hydrogen production.

Production of sexy batteries using rare earth metals COST us a huge enviomental deficit.

I will stick to my original view that the only reason for the SS hybrid is to enable Brian Souter to milk some much needed cash out of the dafter MEP's in the EU. Souter has some real talent, remember the SNP pledge to re-nationalise railways in Scotland as major independence pledge. Souter suddenly became a major SNP supporter and contributor of funds. The pledge to nationalise railways was ditched overnight.

 

[ulyden]

Normandie was a true steam eletric ship. Not a hybrid. Some submarines where true hybrids by having diesel engines generators batteries and a eletric motor as main propulsion. The germans had a lot of them 70 years ago.

(Maybe they were using hydrogen aswell,charging lead batteries)

Gas turbines are used of several reasons. Power density, weight , total power and maintenance.
Lots of wharships are using meedium speed engines for economic crusing. A warship needing 120 000hp to get 30 knots needs only 35 000hp to get 20knots. Look at QM2. Large meedium speed (Wartsila 46 common rail engines) for crusing and turbines for maximum speed.

For real powerful war ships large 2 stroke is not big enough. Some of the larger ships have 200 000shp and even more. Most of them are running on steam turbines. Some heat the steam by NC power.

For most ship operating at constant speed using diesel eletric is a waste. Loss in generator , motor, kables,and maybe the drive (frequency transformer) are accumulating up to 10% of installed diesel power. Its only for ship that have a wide demand in power that can defend such solution.

If you whant a constant speed propulsion you choose a variable pich propeller.

 

[westernman]

Navy Ship Propulsion Technologies: Options for Reducing Oil Use

I found this in a 2006 report to the US Congress which I found interesting:-

Fuel Cells

Fuel cell technology, if successfully developed for Navy shipboard application,
could reduce Navy ship fuel use substantially by generating electricity much more
efficiently than is possible through combustion. Figure 4 is a Navy briefing slide
comparing the relative efficiency of combustion and fuel cell electric power plants.

The Navy states that “the Navy’s shipboard gas turbine engines typically operate
at 16 to 18 percent efficiency, because Navy ships usually sail at low to medium
speeds that don’t require peak use of the power plant. The fuel cell system that ONR
[the Office of Naval Research] is developing will be capable of between 37 to 52
percent efficiency.”29 As a result of these relative efficiencies, the Navy states that a
DDG-51 gas turbine generator operating for 3,000 hours would consume 641,465
gallons of fuel while ship-service fuel cell plant with a built-in fuel processor (i.e.,
a fuel reformer) for forming hydrogen from Navy diesel fuel would, if operated for
the same period, consume 214,315 gallons, or 33% as much.30 The Navy has
estimated, using past fuel prices, that shifting to fuel cell technology could save more
than $1 million per ship per year in ship-service fuel costs.31 Other potential
advantages of fuel cell technology include reduced maintenance costs, reduced
emissions (and thus reduced infrared signature), reduced acoustic signature, reduced
radar cross section (perhaps because of reduced-size exhaust stack structures).

 

[Assassin]

These figures have been bandied about in engineering circles for some time now, and they have already been discredited by all the experts evaluating them for a variety of reasons. The main reason is the investment to use such technologies being around 30+ times the cost of the savings, meaning the ship has to be in service for 30 years plus to recoup this investment alone.

Maintaining such systems are much more costly, with this factor it is estimated from real world figures that this would increase the figure to 40 years plus before any savings are made.

The figures are also designed simply as sales figures for attracting investment to such schemes from those with a vested interest in supplying and fitting them to ships, nothing more. These organisations have been asked to prove their claims through simulation and real world testing, none are able or willing to do so at this current time. Rolls Royce are the leading experts in turbine development and technologies and even they claim they are rubbish, and they already have a number of gas turbines producing electricity, and have had these for 15 years. I actually worked on the first one of its type for electricity production, and found that American organisations were grossely exaggerating their projections even then.

We cannot dismiss any of these ideas, but we must all be wary of outlandish claims which cannot be substantiated, and always look at who is lobbying and their vested interest as a result of any such awarded contracts.

 

[Latestarter1]

Take a look at http://www.fuelcellmarkets.com/Welsh_Assembly_Government/news_and_information/3,1,28508,1,28534.html

Big chunk of Welsh Assembly budget being blown on a Low Carbon Wales...Nuts!

All the money being made in the industry is from research contacts proving concepts. Time after time the numbers do not stack up. Shame the same money and effort was not directed at keeping the British nuclear industry alive. We did the huge world leading Llanberis underground power staion scheme, pay back was less than seven years of operation and planned to do another on Dartmoor. What happened, we sold all the whole thing engineering expertise included to the Japanese, Mitsui I believe.

Having undertaken work as well as obtained funding from what is now the Carbon Trust as well a Local Authority biofuel trust one cannot be anything cynical. The words 'commercial application' never seem to arise.

Works something like this:

Please provide report on the technical benifits of XYZ.

Submit report, scheme is nuts because.....

Within thirty days you get a cheque with request for further report on ABC.

Submit report, scheme is nuts because.....

Within thirty days you get a cheque with request for further..........

Akin to pursuit of the Holy Grail in Middle Ages.

 

[sneakers]

Hydrocarbons

One of the things that puzzles me is the move to pure hydrogen. Adding atmospheric carbon will produce a effective carbon neutral fuel in a form we are all used too. No need for new equipment and engines.

 

[Assassin]

There are possible uses for electric power, for a large planing boat? definately not, but for a small tender to get from boat to marina wall, yes.

Unfortunately many of these are hypothetical notions bourne by the current environmental trend, and are considered by many as practical ideas althouth in reality they are hypothetical, costly, not environmentally friendly, and fail to deliver.

 

[Latestarter1]

New Azimut

This popped up in my mail and the Bill Dixon hull form looks in my eyes kind of nice.

http://magellanorange.azimutyachts.com/en/#/magellano50/photos

A 50 footer with twin 425's which can cruise in the high teens with over 20 knots WOT as well as ability to run at 8 knots of batteries or genny and in production right now would seem to take the wind out of the big SS news splash.

Still no fan of batteries though.......

 

[MapisM]

Don't worry!

Reading the article in this month's MBY about Sunseeker installing a hybrid power system in one of their 70 footers, I kept asking myself why?

'Salright Mike, I still don't get why anyone would want a Sunseeker, period...