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PD Staff
12-19-2010, 10:07 AM
Thoughts?

http://www.fuelcellsystems.co.uk/store/EFOY1600.jpg

Fuel cells offer a clean, silent alternative to diesel generators. Backed by the UK's most experienced distributor of fuel cells, we offer a wide range of products for many applications including:

Sailing yachts and power boats
Motor homes and caravans
Beach huts
Remote surveillance
Remote monitoring
Task lighting
Construction sites
Cellular base station support


What is a Fuel Cell?
Think of a fuel cell as a battery into which you provide fuel. Electricity is generated by it in a chemical process, just like a mobile 'phone or car battery, but instead of recharging it with electricity it's refuelled like a generator. Just like a battery, it produces DC power.

The process is very efficient in its use of fuel. A fuel cell will typically obtain at least twice the amount of energy from its fuel than, say, a petrol engine would. And because it's a chemical process, not a combustion process, the audible noise is very low and there are no nasty emissions.

When a fuel cell, when a generator?
Buy a generator if:

> Capital cost is the primary consideration
> Noise and exhaust fumes are acceptable
> You'll always be around when you need it running
> - we sell generators too!

Buy a fuel cell if:

> You'd like it quiet
> You wish to keep/use it indoors or near food
> You'd like to do without the exhaust or fuel odours


How do I calculate the size of fuel cell I need?
Because a fuel cell produces DC we almost always couple a fuel cell to a conventional battery then leave the fuel cell running continuously. The battery then takes care of the peak loads. This way, we can run something that needs lots of power (say a 3kW kettle) from a fuel cell that's much smaller (say 65W). (Of course, if the kettle were to be running non-stop then we'd have to use a much larger fuel cell).

Some electrical loads need alternating current (AC) like our kettle. The fuel cell and battery provide direct current (DC) so we use an inverter to change from DC to AC.

So we have to consider how long we need each piece of electrical equipment to run for, multiply it by the power it uses to give watt-hours, add up the watt-hours we'd use in a day, then ensure we use a fuel cell that can cope.

Now using our kettle example, let's say we use it five times a day for three minutes each time - 15 minutes in total. That's 0.25 hours. Multiply that time by the power used by the kettle (3,000 Watts), giving 750 Wh (watt-hours). Because our kettle runs from an inverter we should allow 20% for power lost in the inverter. So 20% of 750 is 150Wh, giving 900Wh in total. All we have to do now is select a fuel cell and battery that will provide more than 900Wh per day - simple!

http://www.fuelcellsystems.co.uk/store/SFC_Fuel_Cells.html

Shife
12-19-2010, 10:53 AM
I've been doing a bit of digging into this and I'd say this is definitely where things are headed. I'd give it a minimum of five years before you start seeing this in widespread recreational marine use. Regardless of the marketing this is still primarily a military/industrial product due to the high cost. A company I've been looking into is projecting entry into the RV market within three years. They will be targeting Europe first because their electrical needs are lower. A unit to satisfy the US need for juice is further down the road.

BobJ
12-19-2010, 11:13 AM
Recent post from the UK solo racing group:

Posted by: "Marco Nannini" m_nannini@yahoo.co.uk m_nannini
Mon Nov 29, 2010 2:19 am (PST)

Most of the french minis and lots of the class40s had them, bear in mind that you still need to carry the methanol for them so I'm still to be convinced they are the way to go...

I did Route du Rhum pretty much entirely on autopilot, run VHF, Sea-me, Sat-C, Iridium, Laptop at all times, etc... I used 50lt of diesel with an average consumption of 200-250 amps day.

With a 1600W Fuel cell weighing 7.5kg + 25lt of methanol for 3 weeks (total 32.5kg) would have covered about half my daily consumption and would have saved 25lt of diesel... so you can see it doesnt add up especially considering the cost of them, the engine with proper alternators is still much more cost effective. A fuel cell running all day is about the same as 1.5 hours of engine at the top of the charging curve...

Pete Goss and some of the 60s had water generators which look like small outboard engines at the back of the boat, an impeller on a bracket that can be swung from tack to tack and capable of generating 20amps, no noticeable loss of speed on a beat and, downwind once boat speed is past 8kt (so not to be used in v light winds). I think these water generators in conjunction with solar panels provide better long term weight and cost effective energy... I will be working in this direction for the Global Ocean Race...

For OSTAR solar panels may not be very interesting, but water gen may well be the way to go especially considering the proportion of beating, topped up with the engine in the light winds.

M.

BobJ
12-19-2010, 11:50 AM
Just for fun, here's my energy budget for the 2008 SH TransPac. We all had to do them but does anyone see the problem with the assumptions?

Ragtime!'s energy budget (http://sfbaysss.org/TransPac/transpac2008/electrical_budgets/ragtime_electrical_budget.pdf)

Born 2 Sail
12-20-2010, 04:47 PM
Just for fun, here's my energy budget for the 2008 SH TransPac. We all had to do them but does anyone see the problem with the assumptions?

Ragtime!'s energy budget (http://sfbaysss.org/TransPac/transpac2008/electrical_budgets/ragtime_electrical_budget.pdf)

7 hours of sun a day?

BobJ
12-20-2010, 05:09 PM
No, that worked out okay (at least on the days it was sunny).

Hint: It's a 35 amp alternator.

Christian
12-20-2010, 08:04 PM
I have also looked at the fuel cells and come to the same conclusion re the fuel efficiency - those suckers gobble up a whole lot of fuel - obviously translating into weight.