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Swapping from red diesel to HVO fuel


Bosley Dave

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38 minutes ago, jupiter1124 said:

Yeah, I did note that I didn't have good figures for boats in my calculation. But...

I'm very skeptical of this figure. Even your 1kW (!?) heat pump will use 24kWh per day leaving you with only 6kW for all your cooking, propulsion and domestic use? I guess that might be doable...?

 

I don't know enough about them and I know that heat pumps are highly rated, but is it really possible to get 500% efficiency when you're transferring heat out of a frozen canal? At that kind of efficiency I start to wonder if it might be more efficient to run a diesel genny to power a heat pump, rather than an Eberspacher? It feels like the long arm of the law of thermodynamics might be looking for me for that comment!

 

Anyway, this was exactly my point (batteries need to 10x before powering our lifestyle from charging points only becomes feasible) so it feels like we're on the same page, even if my calculation was unduly pessimistic out of ignorance.

 

Anyone who has a 5kW Eberspacher/Webasto on a boat will tell you that it doesn't run at full power 24 hours a day even in the depths of winter, or even continuously during the day unless you want to live in a sauna. A heat pump with the same peak output is likely to run at full power for no more than 6-8 hours in every 24, meaning 6-8kWh consumption in winter and much less in summer -- actually it will run throttled down for longer, quieter and more efficient:

 

Those numbers were taken directly from the data sheet of the heat pump I was looking at (Frigomar SC16VFD-E), average CoP is at least 5:

 

25% frequency : 4000BTU (1.2kW) for 200W input, CoP=6

50% frequency : 8500BTU (2.5kW) for 450W input, CoP=5.6

75% frequency : 12000BTU (3.5kW) for 700W input, CoP=5.0

100% frequency : 16000BTU (4.7kW) for 1000W input, CoP=4.7

 

The problem is that they only work down to 5C water temperature, so when it's really freezing cold you need a diesel boiler too -- which is why I didn't go this way. On an all-electric boat you'd have to resort to an immersion heater for water and electric heating, which is not ideal to say the least -- in fact heating and hot water provision is a much bigger problem than propulsion. This could easily be solved by using a closed-circuit heat pump filled with brine cooled by a skin tank (like ground source heat pumps) instead of direct water cooling, but nobody makes such a beast -- yet... 😉

 

Propulsion cruising for a full day (8 hours) would typically use about 14kWh. In summer a solar array that will fit on a narrowboat should yield about 7kWh on average (maybe 2kWh in the depths of winter).

 

Domestic use very much depends on what you do (cooking, washing etc), for the sake of argument let's assume 7kWh.

 

Add all these numbers up and you get to the realistic power estimates I provided, which are much smaller than yours.

 

No way do batteries need to be "10x better" than today -- the only real problem today is cost, especially with the cells you quoted (Winston prismatic) as opposed to those used in EVs. Without a generator (which saves about £10k) and not having to pay for a diesel engine and gearbox, an all-electric solution will make financial sense by the time charging points exist.

 

But the problem of having to move to charging points regularly remains...

Edited by IanD
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2 minutes ago, IanD said:

Those numbers were taken directly from the data sheet of the heat pump I was looking at (Frigomar SC16VFD-E), average CoP is at least 5:

 

25% frequency : 4000BTU (1.2kW) for 200W input, CoP=6

50% frequency : 8500BTU (2.5kW) for 450W input, CoP=5.6

75% frequency : 12000BTU (3.5kW) for 700W input, CoP=5.0

100% frequency : 16000BTU (4.7kW) for 1000W input, CoP=4.7


Fascinating. But isn't there a key piece of info missing from this - what's the ambient temperature of the water that it's drawing its heat from? I'm still finding it hard to believe that for 1kW of electrical power you can get 5kW of heat out of a frozen canal.

If this is realistic, then do you think it might in fact be more efficient to use a diesel genny to power a heat pump than to burn the diesel directly in an Eberspacher?

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1 minute ago, jupiter1124 said:


Fascinating. But isn't there a key piece of info missing from this - what's the ambient temperature of the water that it's drawing its heat from? I'm still finding it hard to believe that for 1kW of electrical power you can get 5kW of heat out of a frozen canal.

If this is realistic, then do you think it might in fact be more efficient to use a diesel genny to power a heat pump than to burn the diesel directly in an Eberspacher?

Possibly yes, you will get electric and the waste heat from the genny we fired up the genny yesterday to charge both banks on the move, before long we had hot water and hot radiators plus charged up batteries. We have a 6kw vetus genny nothing special about it

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6 minutes ago, jupiter1124 said:


Fascinating. But isn't there a key piece of info missing from this - what's the ambient temperature of the water that it's drawing its heat from? I'm still finding it hard to believe that for 1kW of electrical power you can get 5kW of heat out of a frozen canal.

If this is realistic, then do you think it might in fact be more efficient to use a diesel genny to power a heat pump than to burn the diesel directly in an Eberspacher?

 

I added that information -- the answer is that with this model the water inlet temperature (fresh water) has to be 5C or above. One using brine in a closed-loop (skin-tank cooled) wouldn't have this problem, but nobody makes one yet suitable for boats.

 

Yes it is more efficient to burn the diesel in a generator (about 25% efficiency) and use this to power a heat-pump (overall "efficiency" maybe 120% including inverter losses) than to burn it in a diesel boiler (overall efficiency maybe 80%), this would save about a third of fuel. But if you have a diesel (HVO) tank this isn't worth it from a cost point of view given the installation cost, especially if you still need a diesel boiler in winter.

 

Also remember that running a generator gives you hot water "free", assuming it's plumbed into a calorifier coil before the skin tank.

Edited by IanD
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11 minutes ago, IanD said:

The problem is that they only work down to 5C water temperature, so when it's really freezing cold you need a diesel boiler too -- which is why I didn't go this way.

Sorry I missed this bit. So on our hypothetical all-electric charging-point-only boat, you would need to have a 5kW electric heater... and for that you are going to need my 5 tonnes of batteries, not so?

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3 minutes ago, jupiter1124 said:

Sorry I missed this bit. So on our hypothetical all-electric charging-point-only boat, you would need to have a 5kW electric heater... and for that you are going to need my 5 tonnes of batteries, not so?

 

No, heat pumps will be far more common in all applications by then, a small ground-source domestic one will do the job all year (just like in a house) once the prices come down.

 

Like I said, you have to look at what is likely to happen in 5 or 10 years time, not prices and technology today 😉

Edited by IanD
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Just now, IanD said:

Like I said, you have to look at what is likely to happen in 5 or 10 years time, not prices and technology today 😉

Which brings us back to exactly what I said... that batteries need to be 10x better/cheaper/denser/faster to charge.

Though maybe 10x is overly pessimistic. If heat pumps are also better/cheaper/etc I concede that a smaller improvement in batteries would be necessary.

I wonder if you could design a cooker that used heat pump technology? Maybe a fridge/freezer/cooker so you can cook your next meal on the heat taken out of your frozen leftovers!

 

  

19 hours ago, jupiter1124 said:

If you charge your LiFePOs between 20% and 80%, then you only have 60% usable capacity, so 80/0.6 means you need 133kWh of batteries.

And discharging your LiFePOs is not going to be 100% efficient, particularly given that you're running at relatively low voltage and putting it through an inverter, unlike land residential supplies... so let's say 90% efficiency? 133/0.9 = 150kWh batteries needed.

I do also note that you glossed over this part, even if we accept you can manage a winter day on 30kWh, you're still going to need (30/0.6)/0.9 = 56kWh per day between charges, so if you want to last 3 days you're still going to need the 150kWh / 55 grand / 5 tonnes of batteries that you charge for 6 hours twice a week.

 

FWIW I am on your side on this, I'm just trying to be honest and compare apples with apples. My boating lifestyle as it is today wouldn't be possible to run 100% electric entirely from charging points with today's technology. Burning something is still definitely necessary, even if it is nice carbon neutral and clean smelling HVO. I would love to get a boat built in the next 5 years, and I would only consider a diesel/electric (or HVO/electric). And now I know I definitely want a heat pump!

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52 minutes ago, jupiter1124 said:

Which brings us back to exactly what I said... that batteries need to be 10x better/cheaper/denser/faster to charge.

Though maybe 10x is overly pessimistic. If heat pumps are also better/cheaper/etc I concede that a smaller improvement in batteries would be necessary.

I wonder if you could design a cooker that used heat pump technology? Maybe a fridge/freezer/cooker so you can cook your next meal on the heat taken out of your frozen leftovers!

 

  

I do also note that you glossed over this part, even if we accept you can manage a winter day on 30kWh, you're still going to need (30/0.6)/0.9 = 56kWh per day between charges, so if you want to last 3 days you're still going to need the 150kWh / 55 grand / 5 tonnes of batteries that you charge for 6 hours twice a week.

 

FWIW I am on your side on this, I'm just trying to be honest and compare apples with apples. My boating lifestyle as it is today wouldn't be possible to run 100% electric entirely from charging points with today's technology. Burning something is still definitely necessary, even if it is nice carbon neutral and clean smelling HVO. I would love to get a boat built in the next 5 years, and I would only consider a diesel/electric (or HVO/electric). And now I know I definitely want a heat pump!

 

I'm not glossing over the capacity problem. High-quality LFP batteries like Winston and BYD are rated at around 3000cycles when using 0% to 100% SoC, the capacity loss problem using the whole SoC range is mainly with EV batteries using NMC or similar. Nobody on a narrowboat with LFP and a properly designed BMS should be scared of using the full SoC range.

 

You can't cook with heat pumps because they get rapidly less efficient as the temperature difference goes up, it's why domestic ones output "hot" water at 55C not the 85C that boilers do.

 

For narrowboats the batteries don't need to be denser or faster to charge, they just need to be cheaper, and especially closer to EV battery prices ($130/kWh today to car manufacturers) than current Winston cells ($400/kWh retail) -- which will undoubtedly happen, current EV prediction is $100/kWh in 2026 (was 2024 before shortages and raw material supply problems).

 

A heat pump would be great if it worked in winter, this isn't a technical issue, it's just that nobody makes one yet -- all the marine ones (like the Frigomar) are freshwater cooled.

 

Your lifestyle would be possible on an electric boat with current technology (with a heat pump, see above...), just *extremely* expensive due to battery cost -- and there are no charging points... 😞

Edited by IanD
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16 hours ago, Bargebuilder said:

We all sign declarations when we buy red diesel, so the authorities must have some way of checking, don't they?

 

But has anyone ever been inspected?

But what are they going to inspect, I have nothing to show them. There is no requirement to keep records as a private boater.

 

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16 hours ago, Lady C said:

The seller of the diesel is required to keep the declarations and may be inspected.

 

I think that is understandable as they could sell diesel at say 40 domestic ad 60 propulsion and then tell HMRC they sold it all at 90 domestic and 10 propulsion. Something that if it happened would involve much larger sums of money per offence and is also, from HMRC point of view something easily audited. 

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Surely on an all electric boat you would use a diesel drip stove like a Refleks to heat it in the winter. No electricity needed at all and the possibility of heating one pot meals on the top of it 

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19 minutes ago, cuthound said:

Surely on an all electric boat you would use a diesel drip stove like a Refleks to heat it in the winter. No electricity needed at all and the possibility of heating one pot meals on the top of it 

Or a oil fired Rayburn with backboiler to heat water and radiators by gravity? That way you can really cook 

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1 minute ago, peterboat said:

Or a oil fired Rayburn with backboiler to heat water and radiators by gravity? That way you can really cook 

 

Could make the boat uncomfortably warm in summer if the recent heatwave becomes the norm.

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1 hour ago, cuthound said:

Surely on an all electric boat you would use a diesel drip stove like a Refleks to heat it in the winter. No electricity needed at all and the possibility of heating one pot meals on the top of it 

Certainly an alternative to a diesel heater. Takes up more space inside the boat, if that matters. But of course an "all electric boat" wouldn't even have a diesel tank... 😉

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2 hours ago, cuthound said:

 

Could make the boat uncomfortably warm in summer if the recent heatwave becomes the norm.

I use an induction hob in summer as I have plenty of electric 

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8 minutes ago, peterboat said:

I use an induction hob in summer as I have plenty of electric 

Thats what we use now, really impressed. We have a two plate model each 800Watt but can't support the two flat out, but one high and one simmering is fine.

 

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2 hours ago, IanD said:

Certainly an alternative to a diesel heater. Takes up more space inside the boat, if that matters. But of course an "all electric boat" wouldn't even have a diesel tank... 😉

Most have though, for their massive diesel generator that’s also fitted. I take it yours will have a diesel tank for the diesel generator?

Edited by PD1964
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35 minutes ago, PD1964 said:

Most have though, for their massive diesel generator that’s also fitted. I take it yours will have a diesel tank for the diesel generator?

Of course, hopefully filled with HVO. But then it's a hybrid, not an EB -- same distinction as with cars... 😉

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19 minutes ago, IanD said:

Of course, hopefully filled with HVO. But then it's a hybrid, not an EB -- same distinction as with cars... 😉

So what engine are you using? Something like the Beta hybrid???

Edited by PD1964
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13 hours ago, IanD said:

Certainly an alternative to a diesel heater. Takes up more space inside the boat, if that matters. But of course an "all electric boat" wouldn't even have a diesel tank... 😉

 

The tank and oil drip stove wouldn't take up as much space as the batteries and heater needed to keep the boat warm overnight... 😉

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16 hours ago, cuthound said:

on an all electric boat you would use a diesel

Read that back to yourself slowly... 😀

 

12 hours ago, peterboat said:

I use an induction hob in summer

Yeah, where electric boats are really amazing is in Summer, you would likely oversize everything to extend the solar powered period of the year as much as you can (9 months on solar only is doable I think, if your "all electric" boat burns something for heating/cooking). For the hottest months you should even be able to reverse your heat pulp and get air conditioning.

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I wonder if, similar to running a genny for your heat pump, it might be more efficient to run a genny to power an induction hob? I should have thought that burning the diesel directly would be better but I might be wrong.

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11 minutes ago, jupiter1124 said:

 

Yeah, where electric boats are really amazing is in Summer, you would likely oversize everything to extend the solar powered period of the year as much as you can (9 months on solar only is doable I think, if your "all electric" boat burns something for heating/cooking). For the hottest months you should even be able to reverse your heat pulp and get air conditioning.

 

Shore power at the waterside is rare.

Maybe that needs to change.

 

 

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2 hours ago, MartynG said:

 

Shore power at the waterside is rare.

Maybe that needs to change.

 

 

One Bollard point on Eastwood moorings that’s working and is the only one that has worked in a long time. Now permanently used by a boat that has conveniently broken down(awaiting spares) for the last 3 month.  

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