Off Grid? What is your Daily Power Consumption?

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Off Grid? What is your Daily Power Consumption?

Postby 470rigby » Sun Mar 28, 2010 1:51 pm

I have sometimes wondered whether subsidies for renewable energy simply encourages extravagant use? Could it be that, in much the same way that installing Ceiling Insulation has been shown to lead to increased energy energy consumption for heating and cooling because people get into a comfort zone, and just want to get more comfortable?

Searching this forum with the key words "daily power consumption" throw up some very high power consumption figures....mostly by people on the Grid based Solarsytems. Is this a vindication of this notion? And if seemingly those with Off-Grid systems are getting by with less energy consumption, then why can't those on the Grid?

So it prompts me to ask the question. If you are Off-Grid, just what is your daily consumption, and what are your strategies for minimising it?

In my case, the two off use use 4KW per day on average. We heat the house in Winter with a Wood Heater which runs 24/7. Possible because we have 40 acres of trees, mainly Box, but some Red Gum (both good fuel). The Fridge is a 420L Westinghouse which eats up about 1 KW per day on average. (slightly more in Winter, because the Wood Heater keeps the interior at around 25 Deg around the clock). Cooking and Hot Water is by LPG, and the useage is minimal for most of the year except when the Wife gets into slow Casserole cooking in mid-Winter. We do much of our Summer cooking outdoors in Summer, with Roasts etc done on a Webber Q, which uses very little gas. Also keeps the house cooler AND keeps the flies outside. In Summer here (Victorian Alps) it is not unusual for overnight temperatures to drop to 10 Deg C, even though the daytime max might have been in the mid 30's. So all the windows are opened once the outside temp drops below the inside temp. (checked using Thermometers). Rarely does it get obove 30 Deg inside, and if it does we use $20 fans that consume about 30W for some personal comfort. This is in spite of having an Air Conditioner which is really only there for that 45 Deg day when the Bushfire is bearing down on us, and we have to take refuge inside. In that case, the Diesel Generator will be running anyway to keep the Pressure Pumps running!

We have a small guest cottage with LPG Cooking, Heater & Fridge. Cooling is with a small Evaporative Cooler which uses rainwater. With no bleed-off required, the water consumption is minimised.

Pressurised water is provided by Pressure Pumps fitted with Pressure tanks which reduce power consumption by about 20%. Not that they are major energy consumers; only drawing about 400W per day.
I had thought about installing Header Tanks and Solar Pumps until I came up with this figure!

The Floor mostly gets swept, rather than using the Vacuum Cleaner. But, the Hairdryer does get a solid workout! On overcast days, the Generator gets cranked up to run it, as it does when heavy power tool usage is required, such as a lengthy run with a Sander.

Garden Water is syphoned out of a Dam, thus obviating the need to run Pumps. Low pressure (around 10psi) means we have to use low pressure compatible Sprinklers and Controllers, but by and large this works well enough. The only real problem being Algal growth which blocks up filters and strainers.

I could go on, but I am trying to paint a picture of what can be done when "nessessity has to be the mother of invention".

So, I invite those living independent of Grid Power to tell their story.

Maybe, some of those burning up KWs with Grid based Solar systems might just see what can be done if they truly want to live Green?

Because, whichever way you cut it....the bottom line is...we have to find ways of using LESS energy, not more just because it doesn't come from Coal Fired Power Station!
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Re: Off Grid? What is your Daily Power Consumption?

Postby MichaelB » Tue Mar 30, 2010 8:14 am

I spend a few weeks a month living off-grid and my power consumption is well under a kilowatt a day. It consists primarily of running my notebook 10 - 14 hours a day (my job is entirely based online), a few LED lights, a small screen TV/DVD player + some AA/AAA battery recharging.

I use a zeer pot for cooling food and a couple of bags of ice in the esky a month - if I decide to go into town on a supplies run.

Over summer I run a portable/personal evaporative air conditioner for up to 8 hours a day - but that only uses about 90 watts for the full 8 hours and around 8 litres of water (Mighty Kool unit from the USA). Often I don't run it for that long - just when temps hit over 35 degrees inside. Better insulation would certainly see even less use.

Cooking and some water heating is via gas (under 1 kilogram a week using a camp stove). Heating during winter is wood (like yourself, wood from my block).

Water is gravity fed or when the tank gets down a hand pump is used. Clothes washing is done by hand. Shower is gravity fed (solar shower bag)

I'll be the first to admit it's not what most would consider a comfortable lifestyle - but when I'm out in the bush, I want to feel like I'm out there and would quite happily live like that full time (pretty close to it now as it is); but it does go to show how little you need to get by; even when working a full time job from "home" and without going totally feral :). Of course, being on my own makes things a bit easier too energy wise.

I run a single 130 watt solar panel and 230AH battery. The generator sees no use for 6 months of the year, then a few hours a day during unfavourable days during late autumn/winter/early spring. Eventually I won't need the generator either except for running power tools, which is infrequent.

I'm certainly nowhere near to self sufficient yet though.. and I do get a little tired of canned food lol. I mention the self sufficiency aspect as this plays a role in my real energy consumption - there's all the external inputs I need; e.g someone else freezes/chills my food so I can keep it for a few days (the supermarket), the energy that goes into making the food, my infrequent trips into town etc.; but that applies to most of us anyway - it's another aspect we should be mindful of when looking at energy efficiency.
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Re: Off Grid? What is your Daily Power Consumption?

Postby GeoffHammond » Tue Mar 30, 2010 9:17 am

The two of us use about 4.5kWh per day - at least it has been just over that in recent months (when it has been warmer and our new fridges & freezers have been running). I expect it to drop a bit as the weather cools. The bulk of our refrigeration is not in zones that are heated, so will get some assistance from the environmental chill.

Our cold water is largely gravity fed: gravity takes it onto the roof and into the collection tank; petrol pumps it up the hill to storage and gravity forces it out the taps. Wind pumps water out of the bore into uphill storage for garden and laundry/toilet.

Our hot water comes from solar, boosted by our wood-fired living room heater.

The fire usually only runs of an evening (although sometimes in the afternoon) in cold weather - the combination of mud-brick construction, a big sun-catching atrium and the occasional extra jumper deal with comfort heating. I purchased some firewood for this winter, but there is enough black wattle on the property to maybe double its value, then it is time to throw the chainsaw into the back of the trucklet and head for the forest.

It doesn't get too hot too often in summer, but when it does, we just deal with it.

I have sometimes cooked on the wood heater, but not as much as I could. Otherwise it is on/in the gas stove or sometimes when entertaining in the wood-fired pizza oven outside.

Anything that doesn't need to be left turned on gets turned off at the power point when we're done with it. I gave up most of my electronic toys when we moved here (wanker-class stereo, etc and a geekdom of computing crap) and there is no stand-alone clock in the house (I use the one in the inverter or a mobile phone). Our only electric kitchen toy is a stab-mixer and hair dryers have been banned.

We do watch too much television, which would reduce our consumption and we do have too much refrigeration - notionally to support my hobby and preserve some of our produce. If I gave up brewing and watching television, I would probably have to resort to conversing with my wife and reading books and nobody wants that.

I certainly do not feel that we have traded comfort for energy efficiency and most visitors to our house wouldn't know we're off-grid, were it not for our exuberant smug...
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Re: Off Grid? What is your Daily Power Consumption?

Postby greg c » Tue Aug 03, 2010 10:34 pm

I am a city dweller and use about 10kW/Hrs per day in an all electric, SHW, passive solar home. I would like all the off grid guys to calculate the KW/Hr equivalent of the wood heaters/gas they use as that would give a more accurate measure of the energy consumed. In the city wood heating is frowned upon and very expensive so is not an option.

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Re: Off Grid? What is your Daily Power Consumption?

Postby GeoffHammond » Wed Aug 04, 2010 9:14 am

greg c wrote:I am a city dweller and use about 10kW/Hrs per day in an all electric, SHW, passive solar home. I would like all the off grid guys to calculate the KW/Hr equivalent of the wood heaters/gas they use as that would give a more accurate measure of the energy consumed. In the city wood heating is frowned upon and very expensive so is not an option.

Greg


It would be interesting if it were doable, which I doubt. We'd then want to look at the weather around each participating house to normalise(?) energy consumption figures. F'rinstance, if I am getting it right, you would *expect* Gordon to use less energy to heat his house than me because I live in a generally colder place.

This year, we burned wood that we purchased, but next year all our heating will come from timber that fell in storms within 200metres of the house. I believe there is someone who frequents this forum who is growing their own firewood(?). How much can we complicate things there?

I agree that it would be interesting to get an overall 'per head' energy consumption. I work where I live, so commuting-based energy becomes relevant as does (it *could* be argued) some component of the energy expended on your behalf by your employer, either for comfort or as part of you earning your income (as the energy I consume is my work and play energy consumption). Or, I'd have to subtract some component of my total energy consumption based on the fact it is 'income-generating' energy and not 'home' energy.

Let's not even start on food.

Don't get me wrong; I'm not having a go at you or your point. I do, however, think that like so many things these days, there is no simple answer.

As an aside, our daily electrical consumption is now hovering around 3.8kWH because I'm not brewing quite as much and we have installed a curtain to separate living areas from balance of house...
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Re: Off Grid? What is your Daily Power Consumption?

Postby Gordon-Loomberah » Wed Aug 04, 2010 9:48 am

As Geoff says, its not something that is easily worked out, there are just too many variables. The energy content of wood varies significantly, as does the efficiency of wood stoves and heaters, the amount of insulation in a house, how warm you like to be, weather, area of the house, etc.
Geoff's daily consumption figures are well under mine, but I use quite a bit of power with power tools, welding, electric cooking, dishwasher, and a heater in a box on the veranda that has been constantly on for the past month to keep 11 young chickens warm, and uses 0.6kWh/day. Gas for cooking runs at about 2 * 8.5kg bottles per year. Our wood fired Everhot stove which will also combine with the solar hydronics heating is still in the shed, and still some time from installation into the house, so we have been using 8.5kg gas bottles for extra heating as there hasn't been much solar heating of late, with continuing clouds (and 170mm of rain in the past 3 weeks). Once we start using the stove, we have more than enough dead timber lying around to keep it running, and all the tree planting that I have done over the past 18 years will ensure we have an ongoing supply vastly in excess of our wood demand.
I've started thinking about induction cook tops for the kitchen, so we can eliminate gas use completely, but the cost of them is a bit scary at the moment.
Today is looking sunny so far :) I'm hoping the batteries will get to float for the first time after a week of cold wet weather, I feel a 13+kWh day from the 2.19kW array coming on 8-) ...and I have some more welding on the WTG tower planned for today :)
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Re: Off Grid? What is your Daily Power Consumption?

Postby Bthree » Wed Aug 04, 2010 9:54 am

some very good points Geoff,

Do people who work consider the energy they consume while they are away from the home as attributed to themselves, even there transport too and from... fuel /electricity for car, train. tram, bus, etc
Then in the work environment, lighting, heating, cooling, waterusage

Ahh the list goes on but I do wonder in Victoria each person is supposed to use only 150litres water per day, something like that but do they take into account water used in the workplace or at the Gym... etc.

Too hard me thinks
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Re: Off Grid? What is your Daily Power Consumption?

Postby 470rigby » Wed Aug 04, 2010 12:47 pm

greg c wrote: I would like all the off grid guys to calculate the KW/Hr equivalent of the wood heaters/gas they use as that would give a more accurate measure of the energy consumed.

Since the figures for Gas consumption has been addressed, I will comment on Woodheating.

My Woodheater is nominally rated at 12kW and this is considered a low rating. But that would be at maximum air intake, which it rarely is. And of course it is only used in the colder months.

When you work through the figures from first principles, the actual thermal energy outputs are gargantuan!

For example, I use about 3 metric tons of wood per Winter. Assuming a Biomass Energy Content of 15GJ/t, my annual usage is 45GJ or 12500 KW. Assuming 60% efficiency (common for modern heaters) my heater will put out 7500 KWh annually, and if taken over 150 Winter days, the daily figure becomes 50 kWh!

All my wood is collected from treefalls on my property and it is conventional wisdom that Greenhouse Gas emissions are the same irregardless of whether the wood is burn’t or allowed to decompose.

But that is not the point here. Nor is the point that my use of wood for thermal energy makes no demands on Grid supplied electricity, which would also be the case for Grid connected PV systems that were energy neutral.

But, even if you collect your own firewood, there is a substantial personal cost. Add up capital costs for Chainsaws, Woodsplitters/Handling Equipment/Drying&Storing Infrastructure (Sheds) etc, and operational costs (fuel/saw blades etc).

The point is that I get no subsidies for using wood as a carbon neutral source of energy; a bit different to the effective cost of subsidies for rooftop grid-connect PV sytems that are subsidized by the taxpayer to the tune of $250 per tonne in terms of carbon emission abatement.

These subsidy schemes have the added downside that there is no real incentive to reduce energy consumption. I suspect that they end up as an inducement to consume more!
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Re: Off Grid? What is your Daily Power Consumption?

Postby GeoffHammond » Wed Aug 04, 2010 1:06 pm

470rigby wrote:<snip>

But that is not the point here. Nor is the point that my use of wood for thermal energy makes no demands on Grid supplied electricity, which would also be the case for Grid connected PV systems that were energy neutral.

But, even if you collect your own firewood, there is a substantial personal cost. Add up capital costs for Chainsaws, Woodsplitters/Handling Equipment/Drying&Storing Infrastructure (Sheds) etc, and operational costs (fuel/saw blades etc).

The point is that I get no subsidies for using wood as a carbon neutral source of energy; a bit different to the effective cost of subsidies for rooftop grid-connect PV sytems that are subsidized by the taxpayer to the tune of $250 per tonne in terms of carbon emission abatement.

These subsidy schemes have the added downside that there is no real incentive to reduce energy consumption. I suspect that they end up as an inducement to consume more!


Mega-Agreement here, I'm afraid.

Once you factor in the financial cost of turning trees into heater-ready wood - even if you value your time at zero - it is hardly an economic exercise.

In our house, we are of the firm opinion that all government policy is constructed such that we receive no benefit. There's a little handbook that gets passed from Government Head to Government Head, the content of which is largely unknown, but there is the 'Geoff and Sarah' rule. ;)

Is it too Conspiracy-Theory to think that subsidies exist primarily to benefit companies involved in manufacture and supply? (At which point I probably should include a link to the incandescent v fluoro bulb discussion.)
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