Low Energy Freezers

The greenest watt is the one you don't have to create. Energy efficiency is the low hanging fruit of greening our homes. Ask your questions or post your energy efficiency tips in here!

Low Energy Freezers

Postby zzsstt » Sun Jun 24, 2012 10:23 am

I've been contemplating various ways of reducing our grid power usage. Because we are on a farm, we have several fridges and freezers including a large-ish chest freezer for bulk storage.

It seemed that this presented an opportunity to save some $, so I did some investigating. A completely ordinary Westinghouse 315L chest freezer is rated at 402kwh/year, and costs about $750 (lowest price is about $700). On the other hand, an "efficient" Vestfrost 312L chest freezer uses 302kWh/year - a 25% saving. However that Vestfrost costs $1700. At 30c per kWh, the 100 kwh/year saving equates to $30 - which would only take 32 years to pay off the difference in purchase price. A bargain!

The Elcold attempt is better at 255kWh/year, but I can't find an Australian price and the NZ price converts to AU$1425 - still 6 years to pay off the extra capital, and that's a NZ price without freight to Australia.

Once again the reality is that its cheaper to burn the kWhs!!!!

Next possibility, convert the existing freezer to solar. The user manual says "not recommended for alternative power". Why? Time to put the PowerMate on it and see what the numbers really look like!!!

Edit:

I put the PowerMate on the old Chest freezer (Kelvinator). The "running" current is about .65 amps, but the start-up spike is 5.6amps (1.34kW) though of course only for a split second. But on that basis an inverter with a 2kW surge rating should be ample. Now I need to see what the daily consumption is (and allow for the low ambient temperatures!) and figure what batteries and panels might run it.

If a freezer (according to the gvernment star rating) takes 500kWh/year to run, thats about 1.4kwH/day. Assuming a worst case (mid summer) of twice that, then the requirement would be for 3kWh/day of PV, which should be less than 1kW of panels. I'm beginning to suspect that an inexpensive island system to 100% power the freezer would pay for itself far more quickly than buying an "energy saving" freezer!!!
zzsstt
Solar Crusader
Solar Crusader
 
Posts: 1296
Joined: Fri Oct 02, 2009 2:27 pm

Re: Low Energy Freezers

Postby Smurf1976 » Sun Jun 24, 2012 2:25 pm

It reminds me of the TV I bought in late 2007 (I didn't have a working one, so not buying wasn't a serious consideration).

Anyway, I could buy a nice big 42" plasma for about $1400 (brand name) or I could have paid $1000 more for an LCD one the same size. The plasma uses 350W, the LCD uses 250W.

No prizes for guessing that I bought the plasma. No realistic amount of use, or realistic price for electricity, made the LCD worthwhile as a means of saving energy. And, back in 2007, the plasmas seemed to have a better picture too so there was no reason whatsoever to go with LCD.

No doubt that has changed now, but it illustrates the point. Most things concerning energy ultimately come down to an economic decision. The only real exceptions are things like laptop computers, satellites or other things where there are non-financial reasons why you want to make it as energy efficient as possible.

There may well be environmental reasons to save energy too. But if it costs $X to save a kilowatt hour versus a quarter of that to generate it from wind or solar then I doubt that many would see the benefit in efficiency.
Smurf1976
Solar Crusader
Solar Crusader
 
Posts: 1037
Joined: Mon Oct 26, 2009 11:56 am

Re: Low Energy Freezers

Postby Tracker » Mon Jun 25, 2012 8:05 am

.
This is yet another variant to the thoughts in the other thread on Unapproved Installations..
The first thought is HOW do you make a freezer SOLAR...?

The only certain way is to install an island system, so that the freezer will run 24-7.
Is it not simpler to say you will buy the panels and a small inverter, and roughly generate the equivalent power, and use the GRID, as your backup and surge supply...
..
.
Tracker
Solar Crusader
Solar Crusader
 
Posts: 5111
Joined: Wed Sep 23, 2009 5:54 am
Location: SYDNEY --- EA - Network, Retailer - EA

Re: Low Energy Freezers

Postby zzsstt » Mon Jun 25, 2012 8:45 am

Tracker wrote:This is yet another variant to the thoughts in the other thread on Unapproved Installations..
The first thought is HOW do you make a freezer SOLAR...?

The only certain way is to install an island system, so that the freezer will run 24-7.
Is it not simpler to say you will buy the panels and a small inverter, and roughly generate the equivalent power, and use the GRID, as your backup and surge supply.


With the laws in NSW, adding to an exisiting PV system is not possible (unless those rumours turn out to be true, but that's in the future). So the income from a GFIT system is fixed, and any new net FIT system can only contribute to daytime costs with a 0c FIT, or in a very minor way with an 8c FIT. So the island system rears its head again.

My thoughts were cost based. A 25% energy saving freezer costs $1700, so it seemed to me that at least that amount could be spent on an island system to achieve the same (or better) result. So, about $900 buys 750W of panels. Add $175 for mountings, and a bit for cables. $400 buys a Taiwan built 1500W pure sine wave inverter, and $100 gets an MPPT charge regulator. That's $1575, but then we need batteries. I must say I haven't completely investigated the batteries yet, but a pair of 12V 150Ah batteries can be bought on eBay for about $700.

So the entire system would cost about $2250. It would not require approval, being a completely island system, and would not require an electrician as the 240V end is all "plug in" with no hard wiring. It would seem to have ample capacity to run a freezer, and could probably be leveraged to run a small irrigation pump for the vegetable garden and possibly some other light duty work (charging cordless tools, lighting for the shed etc.) as long as capacity was monitored.

Obviously I haven't been through the fine detail of matching dc voltages between panels and charge regulator etc., but all the items are on sale at those prices on eBay right now. So the comparison becomes $1700 to save 25% of the power, or $2250 to save 100% of the power and possibly more. In terms of payback, the $1700 new freezer pays for itself in 32 years, whilst the $2250 island system pays for itself (100% of 400kWh/year = $120/year) in 19 years.

Unfortunately both approaches still cost more than grid power, as I said above it is cheaper to burn the kw's!! But PV is getting cheaper and the grid is getting more expensive.....
zzsstt
Solar Crusader
Solar Crusader
 
Posts: 1296
Joined: Fri Oct 02, 2009 2:27 pm

Re: Low Energy Freezers

Postby Gordon-Loomberah » Mon Jun 25, 2012 9:48 am

You seem to be forgetting (possibly) the best and least expensive option!

Assuming it isn't one of the ridiculous "new improved" freezers where they put the heat generating condensor coils into the walls, right next to the bit you are trying to keep cold, then just spend a few bucks on some 75 or 100mm polystyrene insulation and cover the lids and walls. Power use should drop substantially, perhaps even to half what it uses now, since most of the running energy use is due to heat getting in through the walls and lid, not from opening the lid, plus of course any warm items you put in that need to be brought down to -18C or whatever you run it at.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
User avatar
Gordon-Loomberah
Community Moderator
 
Posts: 5760
Joined: Thu Sep 24, 2009 9:41 pm
Location: Loomberah NSW Australia

Re: Low Energy Freezers

Postby Gordon-Loomberah » Mon Jun 25, 2012 9:59 am

Smurf1976 wrote:Anyway, I could buy a nice big 42" plasma for about $1400 (brand name) or I could have paid $1000 more for an LCD one the same size. The plasma uses 350W, the LCD uses 250W.


Efficiency sure has improved a lot since 2007. We had to buy a new LED/LCD TV a couple of weeks ago due to the ancient cathode ray unit finally expiring, after it had been on the blink for quite some time. The new Samsung 80cm tv only uses about 30W running, and 2-3W on standby. I know its a bit smaller, but 250 - 30W is a factor of >8 difference, vs a factor of <2 in area.
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
User avatar
Gordon-Loomberah
Community Moderator
 
Posts: 5760
Joined: Thu Sep 24, 2009 9:41 pm
Location: Loomberah NSW Australia

Re: Low Energy Freezers

Postby zzsstt » Mon Jun 25, 2012 6:29 pm

Gordon-Loomberah wrote:You seem to be forgetting (possibly) the best and least expensive option!


I had considered doing that (and also to the coolroom), as I have a stack of 2" extruded polystyrene sheets in the shed. The only problems are that it's incredibly ugly and not quite as "wipe clean" as appliance white paint! My plan was to wait until the summer, and then scan the freezer with an IR thermometer to see exactly where the warmer and colder areas are. I'd also thought about investigating whether the condensor coils can be spaced off the unit enough to allow extra insulation to be inserted.

On the other hand, the lure of the PV approach is that I can leverage the system to drive a pump to irrigate the vegie patch etc.
zzsstt
Solar Crusader
Solar Crusader
 
Posts: 1296
Joined: Fri Oct 02, 2009 2:27 pm

Re: Low Energy Freezers

Postby Smurf1976 » Mon Jun 25, 2012 10:22 pm

Gordon-Loomberah wrote:EThe new Samsung 80cm tv only uses about 30W running, and 2-3W on standby. I know its a bit smaller, but 250 - 30W is a factor of >8 difference, vs a factor of <2 in area.

A bit off topic I know, but this is a fairly good example of the inertia which exists so far as adoption of energy saving technology is concerned.

In this example, it is not economically sensible for me to replace the plasma with an LED TV simply to save energy. But equally, plasma would seem to be an obsolete technology that would not make sense to purchase today. So it's a classic "use it until it breaks" scenario. Keep running what you have, even though it would be unwise to buy it new today, because doing so is the most financially sensible option. Then get a more energy efficient one whenever the old one dies.

The same situation applies to everything from factory boilers to aircraft to hot water systems. It doesn't make sense to scrap a 10 year old plane just because a new one uses less jet fuel, but equally you wouldn't buy a one built to an old design today. So you're stuck with a "use it until it's worn out" situation.

Likewise for many people it stacks up financially to go solar for hot water only if they need a new HWS anyway, thus reducing the "extra" cost of going solar. That was certainly the case for me - cheapest option was to keep using the electric off-peak HWS since I already owned it. But once it broke only a fool would have replaced it with one the same.
Smurf1976
Solar Crusader
Solar Crusader
 
Posts: 1037
Joined: Mon Oct 26, 2009 11:56 am

Re: Low Energy Freezers

Postby zzsstt » Tue Jun 26, 2012 7:15 am

I suspect that the same thing actually applies to embedded energy, and is one of my concerns about the whole green movement being "sold" new products that increase overall consumption rather than decreasing it.

Most things can be made to last almost indefintely, and the cost of energy and resources taken to produce something almost always outweighs the energy it uses, unless it has a very long life. So whilst my old Massey 65 tractor may use more fuel than a new one, in global terms the equation is not so simple. Over its 60 year life, it has been manufactured once and has used several thousand litres of diesel and several hundred litres of oil. Had that tractor been replaced every 10 years with a more economical model, the total may have been 20% less fuel used, but what about the additional embedded costs of making 6 extra tractors?

We seem to be moving towards a situation where the latest generation of any given piece of equipment uses a fraction less energy than the previous generation but at the same time is obsolete for technical reasons, or simply worn out and broken, far more quickly. So the total energy bill seems to be rising due to the need to keep manufacturing new items, rather than falling due to the relatively small reduction of "in use" consumption.

With regard to my original post, the previous owner of my farm left a very old fridge. It was, I'd guess, a 1950's model and still worked. It may have used more power than a current model, but over its lifetime I wonder if it was really any worse for the planet that the string of fridges that he would have needed had he replaced old trusty with a typical "last until the 5 years interest free credit is paid and then die" modern one?
zzsstt
Solar Crusader
Solar Crusader
 
Posts: 1296
Joined: Fri Oct 02, 2009 2:27 pm

Re: Low Energy Freezers

Postby Tracker » Tue Jun 26, 2012 7:52 am

The great majority of fridge and freezers use the new concept of the HOT pipes being built into the outer case..
External insulation is usually impossible.

You mention the LIFE expectancy of modern products, and I comment that only last week , I saw two seven YO Westinghouse devices that you would be proud to own, and thrown out, because the compressors failed to compress...
The owners did not want to repair them.
Next week, it will cost far more to fix them, thanks to JULIAr and her Carbon-GST tax...

One would start to question if the expensive Efficient device, might be better made and with better quality parts, including pipes that are a bit thicker than five angstrom...

We will all have to start questioning VALUE...

Congratulations Labor, for being so interested in the environment that people now replace products that yesterday would have been repaired.. So now we just sit back as all manufacturing and all service industries, spiral into oblivion... At least we can all turn to installing PV systems..

BTW..... A lot of modern fridges have pressed in back plates... If you can confirm that no warmth can be felt here when the compressor is working hard, the this would be a good place to add insulation..... A 25% cover
improvement...
..
.
Tracker
Solar Crusader
Solar Crusader
 
Posts: 5111
Joined: Wed Sep 23, 2009 5:54 am
Location: SYDNEY --- EA - Network, Retailer - EA

Next

Return to Energy Efficiency

Who is online

Users browsing this forum: No registered users and 1 guest

new solar power specials