Bang goes the Theory

[AndrewSchofield]

Did anyone see 'Bang Goes the Theory - The Human Generator' on BBC1 last night? It was basically about the amount of electricity we use(waste) in our homes every day. In one section of the show, the tech guy they've got was trying to show how much heat energy is produced (and therefore wasted) by traditional filament bulbs by cooking a whole chicken in 90minutes using the heat from just two 100W filament bulbs. He was trying to highlight why low energy bulbs are so much better but i think this raises another issue:-

We had family round for sunday lunch last week and cooked a chicken in our electric fan assisted oven. This took 2 1/2 hours to roast in the oven with the oven rated at just over 2kW. Now i know the oven only uses this amount of power while it is actually heating up and once up to temperature it only comes on periodically to maintain the temperature but it would only have to be using 2kW for 6 minutes to use the same power as 2x100W bulbs do in an hour. So why aren't we using filament bulb technology to cook food? I reckon he used 0.3KwH to cook his chicken compared to our oven, which, if it only consumed power for 1/4 of the time the chicken was in (and that doesn't include the time it took to warm up initially) consumed 1.25KwH - over four times as much?

I presume there must be a reason, just wondered if anyone knows what it is??

 

[Chukka63]

i saw it but it was 2/60watt bulbs i think you'll find. i havent got a bulb oven so im sticking to the main oven.but then i just cook those roasts in a tin from asda,taste yummy and cooked in 50 mins i think

 

[AndrewSchofield]

i saw it but it was 2/60watt bulbs i think you'll find.

If it was two 60W bulbs that makes it even worse?!?

 

[cmother1]

I didn't see it, but I'll bet his chicken was in a much more confined space than a normal oven and so there was a far smaller volume of air to heat. With the right insulation you could confine the heat to the job of cooking instead of venting it into the kitchen which quickly becomes as hot as an ..er.. oven. You then have to put on the extractor, thus wasting the heat completely.

 

[AndrewSchofield]

You're assumptions are correct CM, it was smaller than a standard oven - but not tiny and it was also surrounded on all sides, top and bottom by at least 4" of some sort of insulation. Do normal oven's not have some sort of insulation in them then to stop them wasting so much of the heat they're designed to produce?

 

[Richard C]

I presume there must be a reason, just wondered if anyone knows what it is??

The 120W “light bulb” cooker certainly set me thinking as well. It makes you realise just how badly insulated & inefficient domestic appliances must be.

Got to be down to the oven being made from what looked like 150mm Celotex or something similar & virtually no heat loss, even the steam seemed to remain in there until he took the fairly tight fitting lid off so it was, presumably, also acting like a form of low “pressure cooker”.

 

[cmother1]

Mine seems to have about 1" of rockwool bagged up in metal foil directly around the inner oven. There's a 1" gap and an outer casing around this. Here's the wasteful bit though - the outer casing has a cooling fan in it to stop the build up of heat becoming too great in a chipboard enclosure potentially causing a fire and/or b*ggering the electronic oven controls. This is a completely separate fan from the one inside the oven compartment that circulates the heat internally. Net result is that the kitchen warms up very nicely. Rather an expensive way to do it, though.

 

[Chukka63]

ive just done my own experiment.dont try this at home.ive got chicken grease all over my dining room table after laying my chicken over the double bulb light fitting.

 

[Johnmelad502]

Just watched it on BBC I player. I was amazed at how much energy we (me included) waste.

However, I now have the perfect excuse not to shower once a month. Twice a year from now on and I will be quids in.

 

[Chukka63]

if you wanna be green and save money.disconnect your gas ,water and electricity supply.simple

 

[ColJack]

so is it time for "digital" ovens then?

rather than a single element that is cycled on and off, a series of smaller elements on permanently to generate and maintain a steady heat could be used..

say 20, 40, 80, 100°C ?
this gives a range of temperatures from 20°C - 240°C..

 

[satansbrother]

if you wanna be green and save money.disconnect your gas ,water and electricity supply.simple

Going green in The UK is pointless. Our rulers (thieveing, lying, cheatin' politicians) are constantly telling us what wasteful lives we lead, and to use less energy, resources, etc. So we obey like sheep.

Then, they ship millions more people into the country to use more energy and resources. Bonkers or What?

 

[Whitespirit66]

So why aren't we using filament bulb technology to cook food?

You can, but its been refined a little. You can now buy small halogen ovens.

 

[megawatt]

One of Mrs MW's ovens uses a combination of microwave, traditional element and halogen to cook perfectly in a fraction of the time using built in and customisable programmes so I guess I am green in some respects.

Very clever once I'd read and translated the huge manual to her

Also means I can light up the house and drive huge petrol-guzzling cars and feel like I'm doing my bit.

Don't forget, the heat given off by all the devices switched on in the home isn't entirely wasted as the central heating won't need to work so hard

MW

 

[tim west]

The last time I saw the experiment being done it led to the slow cooker being launched