utility vs propane

[Ralph Day]

Hi all
I was running quite low on propane so was using an electric hotplate, when sunny, to heat water. I realized the 1 burner countertop unit was really inefficient, so bought an electric kettle. Incredibly faster, but how much more efficient?

Kill a watt meter on the kettle revealed .11kwhr to bring 1 litre of water to a boil. I didn't bother with the hotplate. The propane range 9100btu/hr burner when timed took about 1100btu's of propane to boil 1 litre of water.

Take the .11kwhr x $.14/kwhr = $0.015 . That's 1 1/2cents to heat the water to a boil.
1100btu's propane / 30000btu/litre = .036litres to heat the water x $0.86/litre = $0.031

So, to heat the same volume of water costs twice as much with the latest tank of propane (86cents per litre), than prime time electrical utility rate. I can see that when I have the utility power "on" or it's sunny I'll be heating coffee and tea water with the electric kettle.

A 420 litre tank of propane lasts me just about 2 years, so now with the electric kettle it should last at least 2 years. Other propane use is flash water heater and cooking (4 burner range/oven) no heating.

More math...if the kettle boils 5 times per day x 1.5cents that's 7.5 cents per day. 5 times with the propane = 15cents. The kettle cost $25 at an outlet store, if I save 7.5 cents per day ... $25 / $.075per day = 333.33days until the kettle has paid for itself. Not a bad investment. Even better when you consider that solar power will likely be used 70% of the time (not utility), so the "payback" time is even less. My better half says I'm not supposed to do those kind of calculations...we don't live off grid (almost off grid really) to save money, it's a lifestyle choice.

Any thoughts? Like what's the number of btu's that the electric kettle used, not just $$. What does my $/btu look like?

Ralph

Just found it. 1btu = 3412.1416watt/hrs. So my .11kwhr kettle used 375btu's to be boiled or about 1/3rd of the btu's of propane. Cool.

[Bryan Couch]

So any time you need a pot of boiling water on the stove you should preboil it in the kettle before filling the pot....:unsure:

A little to much effort for me to save $4 or $5 a year but, it would save money and would use more solar and less propane.

I wonder how many other things there are around the house that would be more efficient to do with electric if you are grid tied or off grid.

[Ralph Day]

Hi Bryan
I was just trying to eek out the maximum use of the cheaper propane from 2012, that's why I mucked about comparing gas and electric.

The difference between having a "sit on burner" kettle being heated by gas or electric hotplate and heating water in a kettle with the element in the water is noticable. About 5 minutes for the immersion kettle, about 10 minutes for the hotplate (a little less for the gas burner). For a quick demonstration, put a kettle of pot of water on a gas burner...hold your hand above the top of the pot a few inches. You can feel a lot of heat that's not been passed through to your water.

This makes me think more about using a crock pot on sunny days.

Ralph

[Brian McGowan]

I use a Black & Decker one cup coffee maker to make my coffee. I run it with my MSW inverter off my solar charged 12V batteries. It takes 3.5 minutes to make a 16oz cup of coffee. The inverter uses 60A.
I use a crock pot in the winter but for the summer I made a solar oven by painting a 2.5Qt pickle jar with flat black grill paint. I made a reflector cone out of one of those windshield reflectors and place it in a 5 gallon plaster bucket with a grill from a toaster oven on that then one of those large plastic pretzel jars with the pickle jar inside of that. It works great.

[Ralph Day]

Brian, you lost me on the description of the summer oven. Any chance of a picture?

Ralph

[Brian McGowan]

Here you go. Best picture I have at the moment.

1101

[Joe Blake]

A few weeks ago I attempted to make a solar cooker using an umbrella and a reflective blanket as used by paramedics.

http://i82.photobucket.com/albums/j245/saxeharp/general10/brolly01_zps8aa95241.jpg

The newsprint is the template I used to cut the foil to shape. I then used contact cement to hold the foil in place.

http://i82.photobucket.com/albums/j245/saxeharp/general10/brolly02_zpsabf3847c.jpg

With a sudden (but welcome) entrance of wintery weather, I've not been able to progress any further, but preliminary indications are that, whilst it's not a true parabola, it DOES concentrate sunlight/heat moderately.

Whilst I was surfing the net to find out a bit about solar cookers in general, I came across this solar kettle.

http://www.sunkettle.com/

http://images.cdn.bigcartel.com/bigcartel/product_images/131183253/max_h-1000+max_w-1000/Product_Details_1a.jpg

Although it only holds half a litre (I usuall make 1 litre of coffee and store it in a thermos flask to consume during the day) it might be worthwhile pursuing as summer comes back.

Joe

[Brian McGowan]

That umbrella idea is clever. I am curious how well it works for you.

I got my idea from this site. I basically made the top center model.

http://solarcooking.org/plans/

[Joe Blake]

This model is almost exactly the same as mine

http://solarcooking.org/plans/paracuina.pdf

Except I think the reflective blanket is a little sturdier than plain aluminium foil. The tripod idea gives me to think a bit more. Thanks for the link

I just took mine out into the backyard. At 11:40 am the air temperature is currently 30 degrees C, and after about 2-3 minutes the temperature at the (rough) focus, was about 44-46 degrees C. I'll need to create some form of clamp to fix the brolly and a means of suspending the cooking pot at the focal area.

Joe

[Brian McGowan]

I was surprised at how fast my oven got hot. I don't know how hot because above 160F It just says HI.

These things work better than you might think.

[Chris Olson]

Any thoughts? Like what's the number of btu's that the electric kettle used, not just $$. What does my $/btu look like?


Electric heating has always been more efficient than gas. The price of gas usually makes it the cheaper option. Most off-grid folks use gas for cooking and if you tell them you can use electricity instead some of them go ballistic and start foaming at the mouth.

We have never used gas here because my wife won't allow it on the property. So I've always looked for ways to do things with electricity instead, because our power system here generates electricity, not propane.

One of the best things we bought for our place was our induction cooktop range:

https://lh4.googleusercontent.com/-nkq3rgwerZg/U13FpHHlr8I/AAAAAAAAIGQ/myvGm0So-Mg/w640-h480-no/100_2526.JPG

It is an Electrolux and my wife had it imported from Sweden and the controls and transformer changed in it for 240V split-phase 60Hz instead of 230V/50Hz. At the time it was virtually impossible to buy a full sized range with an induction cooktop in North America. There are a few places that sell them now, but still nobody stocks them and they usually have to be special ordered. And it requires ferromagnetic or magnetic stainless steel cookware to be able to cook with one.

Induction cooking is incredibly efficient since very little of the heat that is created by eddy currents in the cooking vessel is lost and almost all of it is transferred to the food or contents of the pot. My wife had to have one because her parents and sisters, and just about everybody she knows in Sweden have them. I was very skeptical of it and when we were in Sweden for Christmas in 2012 she bought the range and had it exported to the US. After seeing how efficient it is, and how easily our off-grid power system handles it, my skepticism was unwarranted.

I do not have the proper credentials to use my wife's fancy range. So when I need to do some cooking for myself, I bought a little 120V induction cooktop that I can use without my wife's direct supervision:

https://lh5.googleusercontent.com/-Lixcy2e_VLw/U13I390TTGI/AAAAAAAAIGc/9EZyig_f-qY/w640-h480-no/100_3449.JPG

[Mark Ross]

Electric heating has always been more efficient than gas. The price of gas usually makes it the cheaper option. Most off-grid folks use gas for cooking and if you tell them you can use electricity instead some of them go ballistic and start foaming at the mouth.

We have never used gas here because my wife won't allow it on the property. So I've always looked for ways to do things with electricity instead, because our power system here generates electricity, not propane.

One of the best things we bought for our place was our induction cooktop range:

https://lh4.googleusercontent.com/-nkq3rgwerZg/U13FpHHlr8I/AAAAAAAAIGQ/myvGm0So-Mg/w640-h480-no/100_2526.JPG

It is an Electrolux and my wife had it imported from Sweden and the controls and transformer changed in it for 240V split-phase 60Hz instead of 230V/50Hz. At the time it was virtually impossible to buy a full sized range with an induction cooktop in North America. There are a few places that sell them now, but still nobody stocks them and they usually have to be special ordered. And it requires ferromagnetic or magnetic stainless steel cookware to be able to cook with one.

Induction cooking is incredibly efficient since very little of the heat that is created by eddy currents in the cooking vessel is lost and almost all of it is transferred to the food or contents of the pot. My wife had to have one because her parents and sisters, and just about everybody she knows in Sweden have them. I was very skeptical of it and when we were in Sweden for Christmas in 2012 she bought the range and had it exported to the US. After seeing how efficient it is, and how easily our off-grid power system handles it, my skepticism was unwarranted.

I do not have the proper credentials to use my wife's fancy range. So when I need to do some cooking for myself, I bought a little 120V induction cooktop that I can use without my wife's direct supervision:

https://lh5.googleusercontent.com/-Lixcy2e_VLw/U13I390TTGI/AAAAAAAAIGc/9EZyig_f-qY/w640-h480-no/100_3449.JPG


I thought the oven was the biggest power soak in a range, not the cooktop? What kind of system do you have to power that? Does you generator fire up every time you turn on the oven?

- mark

[Chris Olson]

I thought the oven was the biggest power soak in a range, not the cooktop? What kind of system do you have to power that? Does you generator fire up every time you turn on the oven?

XW6048 inverter. It handles the convection oven with no problem at all. The oven only draws about 4,800 watts. If there's a lot of other stuff going in the house that overloads the inverter, then it will cause the generator to start and run on generator support until the load drops below the continuous rating of the inverter.

The type of inverter we have can share loads with the generator. So we only have a little 4.0 kVA Honda genset. The inverter and generator combined, with the inverter operating in Generator Support mode, can supply 10 kW continuous to the loads. So our system auto starts/stops the generator, as required, whenever the inverter overloads.

The only bad thing is that the inverter will handle 8.0 kVA standalone for about 5 minutes. It starts the genset to help out after a one minute delay when the load exceeds 5.6 kVA. So for the first minute and half that it takes for the system to start the genset, sync with it and bring it online, we have to limit our loads to less than 8 kVA. Once the generator comes online with the inverter in Gen Support mode, then we can throw all the switches we want.

[Mark Ross]

Interesting, thanks.

I don't think I want to run the generator each time my wife wants to use the oven, so I think propane is gonna be our solution.

Sure, we have to buy propane (not generate it), but in a config like yours we would have to purchase fuel for the genny anyway I guess...either way, some fuel is getting burned.

cheers,
mark

[Chris Olson]

We have gone all electric because my wife will not allow a propane tank on the property, much less have a line coming into the house. And I have been very happy with the electric appliances, including her high-efficiency electric clothes dryer, and our electric water heating.

We have a Conext ComBox monitoring and logging system that we put in last August. It keeps detailed logs right to the watt-hour on what comes from generator, solar, how much loads are, etc.. It has logged since last August, 94.3% of the time we are able to run our heavy draw loads without the generator. The only time the genset starts is if we turn on two high-draw items at the same time in conjunction with other normal everyday loads. We have chosen to use the Generator Support feature instead of stacking inverters for peak draw loads because we can get by on half the battery capacity that would be needed for dual inverters, and batteries are the most expensive component of an off-grid system.

So basically, if you chose propane you are locked into one source of energy for your appliance - no options. If you chose electric and can run it 94.3% of the time on power you produce, you have a "dual fuel" appliance that most of time runs on renewable power, and the balance on fossil fuels.

[Chris Olson]

Sure, we have to buy propane (not generate it), but in a config like yours we would have to purchase fuel for the genny anyway I guess...either way, some fuel is getting burned.


I should say that living off-grid is not necessarily an exercise in eliminating use of fossil fuels either. Most of us have chosen to live off-grid because we live in the sticks of the boonies and powerlines don't come here. And even if the powerlines did come here, the chances of them staying up and working are pretty dang slim.

My gripe with propane is that it is one of the most inefficient fossil fuels known to man (besides natural gas). Heavy fuel oils are by far the most efficient and energy dense. Diesel fuel is the most practical for off-grid fossil fuels because unlike HFO, diesel fuel actually flows in cold weather.

If you compare the typical LP-fueled genset to a comparable diesel genset for thermal efficiency, and include the cost/BTU of energy in the fuel, the LP genset isn't even good for a boat anchor because it's not the right shape. The efficiency of gas cooking or water heating with LP is isn't any better. And further, I agree with my wife that LP gas isn't even safe. Even after things like this happen (which is actually VERY common) the gas companies all fire up their advertising machines and say "Oh, it's perfectly safe"
http://www.startribune.com/local/west/47882647.html
http://www.nbcnews.com/id/54996748/ns/local_news-minneapolis__st_paul_mn/
http://www.myfoxtwincities.com/story/24366874/explosion-at-commerce-apartments-in-rogers-minn

And if fact, it is so common that there are attorneys that specialize in it:
http://rochlinlaw.com/explosions-burns

[Mark Ross]

If you chose electric and can run it 94.3% of the time on power you produce, you have a "dual fuel" appliance that most of time runs on renewable power, and the balance on fossil fuels.

I'm not sure how large of a system you would need to run an electric oven. I'm not talking about the cooktop where you could theoretically leverage induction heating, but the electric oven itself (ie. roasting turkey on thanksgiving)

I feel that would be a super heavy load for an off-grid system? Wouldn't you nearly always need to run the genny to power it?

Even after things like this happen (which is actually VERY common) the gas companies all fire up their advertising machines and say "Oh, it's perfectly safe"
http://www.startribune.com/local/west/47882647.html
http://www.nbcnews.com/id/54996748/ns/local_news-minneapolis__st_paul_mn/
http://www.myfoxtwincities.com/story/24366874/explosion-at-commerce-apartments-in-rogers-minn

And if fact, it is so common that there are attorneys that specialize in it:
http://rochlinlaw.com/explosions-burns

You say this as though there has never been an oil spill, or oil pipeline leak, and that liquid oil is somehow safe...? I don't accept that as an argument; in this case both fuel sources have some risk associated with them. Neither of which is likely to directly affect the end user very much at all (at the time of use, at least).

[Chris Olson]

I feel that would be a super heavy load for an off-grid system? Wouldn't you nearly always need to run the genny to power it?

No - we can usually make a pizza in the oven, etc., without using the genset. During heavy draw times (such as Thanksgiving or Christmas) then the generator starts and runs to support the inverter and keep it from overload. But we use 60-70 kWh in a day during those times too. We have found it to be quite efficient and easily powered by our off-grid system - although I designed the system from the ground up to do it that way.


You say this as though there has never been an oil spill, or oil pipeline leak, and that liquid oil is somehow safe...? I don't accept that as an argument

Liquified Petroleum Gas is a byproduct of crude oil refining. So LPG is not going to exist without the crude in the first place. The refining of crude oil into diesel fuel, gasoline and the byproducts like LPG require huge amounts of electricity and that is why refineries are strategically located near major power plants so the power to operate them does not have to be transmitted long distances. The amount of electricity is takes to produce LPG during the refining process is more than the energy in the gas. When the energy in heavier products like diesel fuel are factored in, crude oil refining is net energy positive. But not by very much when the amount of energy it takes to drill for, pump, transport, refine, and transport the refined products are all factored in.

If you do the math on it, the majority of the energy you burn in your car in the form of gasoline indirectly comes from coal to fire the coal fueled powerplants that make it all possible.

The oil industry as we know it today was invented by John D. Rockefeller and Standard Oil. And it was never for the good of humanity - only for profit for those involved in it. The US Supreme Court eventually found Standard Oil to be in violation of anti-trust laws and broke it up. But it did not stop the momentum and domination of the energy industry by petroleum.

Today, even though the petroleum industry is horribly energy inefficient, you pay many times more for the energy in petroleum products than it's actually worth in other forms of energy. Picking which form of refined petroleum you use to get the buy/BTU of energy content is wise. LPG and natural gas are way down on the bottom of the list. Designing your off-grid system to use fossil fuels for certain things as primary instead of backup is only playing into the hands of the oil business that has made trillions in profit off you, the consumer.

Like I said before, I have ran into people who cannot fathom in their wildest dreams being able to run things like electric range, electric clothes dryer, and heat 100% of your water with solar and wind power, only using fossil fuels as backup. We are living proof that it can be done, and been doing it to one extent or another for 14 years. But the design of our system to do it is far from what is considered "normal" in off-grid design - right down to the fact that our system is designed to NEVER let a generator charge batteries except in extreme emergency. And we do it with a single inverter instead of stacked, and with a relatively small (considering our daily energy consumption) 58 kWh battery bank.

IMO, doing what Ralph is doing - using electricity to heat or cook instead of using propane is the SMART thing to do. You can use the electricity direct, even from the utility, or you can use it in the form of refined petroleum products and funnel your money to the oil industry instead. Even better yet is using your off-grid power system to supply the electricity, which is what we do. The oil industry can only survive and make their huge profits off you because of your insatiable demand for what they sell. That's easy to fix and stop the petroleum industry dead in its tracks - stop buying what they sell and re-design your system to use a different energy source, and only use what they sell for backup.

There is no government "regulation" needed, no development of "alternative" forms of energy. You the consumer are responsible for the whole mess we got ourselves into because you make the decisions on what you buy.

[Ralph Day]

Ok then Chris, I'll have to find a 1/2 mile long extension cord to run my chainsaw to cut my wood to heat my home:push:. Some things just gotta be fossil fueled. I use gasoline and diesel to cut/split/move my winter's heating supply (5 cords hardwood).

The wind resource you harvest also puts you in a different league. My little 1kw toy turbine usually nets 650kwhrs per year. 2.1kw pv was quite expensive 10 years ago...all I could afford. A system today would be easier to put together to avoid the fossil fuel trap, but the infrastructure is there for it's distribution and storage (propane, diesel, gasoline). Kudos to those who can handle the build and maintenance of a system like Chris's. I just manage to keep ahead with my little system (daily use of 7 - 8 kwhrs, propane for cooking and water heat).

Ralph

[Chris Olson]

We use, on average, 25-30 kWh/day in winter. 15-20 kWh/day in summer.

I actually have an electric chainsaw, and my wood splitter has a 1.5 hp electric motor on it driving the hydraulic pump. We even have two electric 24V lawnmowers - the rider I built myself and is powered by a forklift traction motor, the push mower that we use for trimming we bought commercially built. We also have electric scooters that we ride into town (and actually all over). We've looked at buying an electric car but we don't generate enough power to charge one.

We still use fossil fuels in the form of diesel fuel and gasoline. But we've tried to use our electricity as primary for most stuff and use the fossil fuels for backup to reduce our use of them. I don't seen anything inherently wrong with the use of fossil fuels other than when you buy them you are sending your money to one of the most lucrative monopolies ever devised by man.

[Joe Blake]

I decided to try out the solar rocket kettle, even though we are now going into autumn. I'm in two minds about it. It works and does pretty much what the maker says it does. On a cool and occasionally cloudy day it heated 600 ml of water to about 80 degrees C, and actually made a decent cup of tea. One cup! Took nearly 2 hours. But I wouldn't want to take it camping with me, my idea of camping is hiking around stopping every little while for a quick break. Not going try and boil water.

I'd much rather use the space in my backpack for a Biolite stove.

http://www.biolitestove.com/Media/BioLite/CampStove/camp_overview_img_2-942x648.jpg

Takes a bit less vertical space, weighs a small bit more than the solar kettle, is nowhere near as fragile (no vacuum tube) and is much more flexible. As well it has the ability to generate electricity to (a) run the fan and (b) charge a mobile phone or torch via the USB port.

The big advantage is that because of the forced draught design, it will burn things that normally wouldn't burn, such as gum tree nuts etc, and gives a higher temperature, albeit at the cost of consuming the fuel more quickly. (If there's one thing I DON'T lack it's gum nuts.) Once it's running properly, there's not much smoke. I don't think I'd want to rely on it solely for all my cooking, but as an emergency back up it's pretty sweet.

There are larger models designed for cooking for a family, but they are not usually available to the general public.

http://www.biolitestove.com/Media/BioLite/HomeStove/homestove.jpg