T-Pain Is On A Boat: Re: [Electric Boats] Re: Prop design and cruising

Wednesday, January 6, 2016

Re: [Electric Boats] Re: Prop design and cruising - pure electric BEV

A prop - best way ? - absolutely not.
Its just the best way we have.

BEV=Battery Electric Vehicle.
BEV=Battery Electric Boat ?

A small/medium cruising powerboat (16 m, 50 tons), with a typical config
might have a 200-300 hp engine on it.
Typical need of power, with the typical (quite) inefficient prop, is
about 30 hp, at maybe/approx 80-85% of hull speed, around 7 knots.
(Nordhavn, cruising for 1300 miles offshore passage, 24x7, actual data
from owner by my faulty memory).

If we put a rope on it, and pulled (via efficient worm gear), we might
find that about 3-4-6 kw (5-10 hp) is actually needed (calm) to get the
7 knots.
With no wind, a person can easily push/pull the boat at 0.5 knots (under
100 watts).
A brisk wind will overpower a person, and you cannot pull the boat in,
and it will escape from you, unless the sheet is wrapped around a
pollard etc.

So, the driveline loses about 2/3 of the power in best case scenario.
We know that ICE engines lose about 1/3 the power due to system losses
(exhaust, noise, oil cooler, marine transmission).

There is plenty of evidence to suggest prop efficiency might be
100-200-300% better.

Other interesting data:
There is an electric car ferry in norway.
80 m long, 20 m wide.
Needs 2 x 70 kW to run the ferry (maybe 200 tons ?), equipped with 2x150
kw electric engines.
LiOn battery, charged in 15 minutes at each end of 1 hour run (900 kW
charge, ie 0.9 MW).

A 24 m displacement boat (steel) a friend owned, 70 metric tons.
A 100 hp engine (from a train) was grossly overpowered with current prop.
Needed power during 6 months cruising (finland, lakes) was about 15-25%
of what was available.
Mostly, under 10%.
Engine was over 1000 kg, and had massive torque.
== Similar to benefits from electric engines - heavy torque at low speeds.

Electric cruising powerboat (ocean crossing).
At this time, it looks like, to me, that a pure electric cruising
powerboat, with transatlantic range, is barely practical today.
With specific energy of == 360 W/kg, todays lion stuff.
Within 2 years (2018), the same battery will be == 450 W/kg, and half
the cost.

Battery cost:
In 4 years, 2020, at 500W/kg, and approx 80$/kW cost, it will be sensible.
Both the costs and efficiencies are a given, and 90% of the work is
done, today.
The timeline is somewhat uncertain, +/- 1-2 years.

At 80$/kw, for 1000 kw, battery costs = 80.000$.
This is much less than the current Nordhavn driveline cost, circa
150.000$, my best guess.
Somewhere between 1-2 MW would give you transatlantic range.
The electric engine costs 2000-6000$/depending, and a VFD/electronic
drive about the same, for == 6-9000 $ engine system.

Battery mass:
500W/kg=> 2 kg/kw => 2000 kg/1 MW, similar to current engine/transmission.
3000 l diesel == 2500 kg.
So, you could have upto 2 MW for same total mass, making the system
eminently practical.

For interesting reads and data, if you want to follow up, the companies
working on this are at least:
By order of importance/capacity/success/skill set (my estimate);
Tesla, BYD, Panasonic
LG Chem (Chevrolet),
Nissan, Renault,
Porsche, Audi, Volkswagen,
+Flow batteries, + solid state batteries (Sakti3/Dyson), + lithium-air
batteries
+Faraday Future, Toroidion,
etc etc etc over 100 small companies.

Both Tesla and BYD, this year 2016, are at over 10GW/year battery
use/build, and about 200-300% more than nearest competitor (Nissan leaf
I believe).
The 1 trillion dollar/year car market will be decided by who makes the
cheapest battery for traction use (within next 2-3 years).
100 million cars/year (by 2020).
1 trillion $ /year (+plus == 10 trillion in power industry).

The first, cheapest battery maker will become the new nr 1. world car
major, due to economics.
And the worlds most valuable company.
This fact has not escaped major industrial companies.
Or the oil majors.
Or the car majors.
Or every power company in the world (distributed storage).
Every PV manufacturer in the world.
Etc.

Current trends:
Tesla leads at approx 165-180$/kWh.
Tesle will be under 100$ by 2018-2020 (65-85 $).
They will, imo, be at 100$, more or less, in 2017 with their new factory
starting this year (Tesla Eneergy, storage products).
Chevrolet states LG Chen sells to them (cells) at 145$ in 2016 (new
Chevrolet Bolt, due in 1-2 years).
Its thus likely LG Chem has costs, now, at == 120 $ or less, and a
roadmap to 100$ or less by 2018.

Li-air has potentially 3400 Wh/kg, today, and 11.400 kWh/kg in theory.
This would, practically-instantly, convert all transport to battery use,
including heavy cargo ships, and all trucking, due to economics.
Its about 7x cheaper to run an electric car, today, than an ICE powered one.

An ICE car in traffic, today, costs about 7€/hr.
An electric one, == 1€/hr.
The economics are obvious.

http://www.forbes.com/sites/williampentland/2015/10/31/lithium-air-battery-breakthrough-may-mean-game-over-for-gasoline/

I follow the technology out of interest, and also because theres money
to be made, to quote a well-known TV personality Richard Quest.
Hope this is of interest.

On 04/01/2016 22:12, Dirk Harms-Merbitz grasswood@icloud.com
[electricboats] wrote:
> Interesting.. makes sense.
>
> Is a propeller even the best way to convert electrical power into
> forward movement?

--
-hanermo (cnc designs)