Which is the most energy efficient ?

[buddha]

Using a gas hob is the most energy efficient way to heat water (although an electric kettle is quicker).
Next is an electric kettle, then and electric hob and least efficient is a microwave, by quite a margin.
With gas there is a 'direct' energy conversion (burn gas to make heat). Whereas with electricity, there the conversion from a base fuel (unless it is from wind, hydro or solar etc) to electricity, with its associated losses (turbine efficiency etc).
Price wise, gas is cheaper too.
Refilling an empty, hot kettle, will also save heating water from cold.

Thinking 'aloud': Why has nobody made a solar kettle yet? Not to boil water, but to at least heat it to above room temperature. Those of you who have solar water heating will know it doesn't take direct summer sunlight to heat water in an enclosed container significantly. It could be similar in construction to the double-skinned tubes of most modern solar water panels you find on a roof. But you just put it on the window sill. I should patent that, but couldn't be bothered.

 

[User482]

Using a gas hob is the most energy efficient way to heat water (although an electric kettle is quicker).
Next is an electric kettle, then and electric hob and least efficient is a microwave, by quite a margin.
With gas there is a 'direct' energy conversion (burn gas to make heat). Whereas with electricity, there the conversion from a base fuel (unless it is from wind, hydro or solar etc) to electricity, with its associated losses (turbine efficiency etc).
Price wise, gas is cheaper too.
Refilling an empty, hot kettle, will also save heating water from cold.

A microwave is the most energy efficient method of cooking the potatoes, as I've demonstrated elsewhere in the thread. On the issue of just boiling water, a gas hob kettle takes about three times as much energy as an electric kettle, because of all the heat losses to atmosphere, and some incomplete combustion of the fuel. That cancels out all the efficiencies you gain from using a primary fuel.

Some people with too much time on their hands have posted some info: http://www.techmind.org/energy/calcs.html

 

[snorri]

I learned quite early in my working life when visiting the home of a customer that a pressure cooker can be used to redecorate the kitchen. First you consume alcoholic beverages then clean and slice some beetroot and put in a pressure cooker with some water, fit lid on cooker in such a manner that when cooker pressure reaches an indeterminate level it will blow off, apply heat to cooker and retire to bed with a few beers, and in the morning.........

 

[threebikesmcginty]

Another method I like to use is wrapping spuds in silver foil and cooking them on the engine of my Hummer but at 4 gallons per mile I'm not sure if this is a saving especially when I have to drive it around just to cook potatoes.

 

[mickle]

Use a panful of hot water from the tap - it's already been heated and will be boiled and sterilised anyway.

As a plumber in a previous life I would strongly recommend never drinking from the hot tap.

 

[summerdays]

I thought that microwaves were only to be used for heating baked beans, I had no idea you could cook other stuff in them.

Peas are best done in a microwave .. much better than in a pan.

 

[buddha]

A microwave is the most energy efficient method of cooking the potatoes, as I've demonstrated elsewhere in the thread. On the issue of just boiling water, a gas hob kettle takes about three times as much energy as an electric kettle, because of all the heat losses to atmosphere, and some incomplete combustion of the fuel. That cancels out all the efficiencies you gain from using a primary fuel.

Some people with too much time on their hands have posted some info: http://www.techmind.org/energy/calcs.html

As ever, a lot depends on the pan being used. The link posted used an (invariably thick) aluminium pan on the hob. A thin based hob kettle is far more efficient.
About a year ago I had a similar (industrial) problem to solve. Albeit with a 'coolant' (approx 98% water). So did some controlled tests with water and coolant. Using a direct flame on a thin walled container was around 10% more efficient than an element in a container.
I also discovered that the vapour produced from heated coolant has a similar odour to wacky-backy, so my results may be a load of b0!!*%ks

 

[summerdays]

Using a gas hob is the most energy efficient way to heat water (although an electric kettle is quicker).


Thinking 'aloud': Why has nobody made a solar kettle yet? Not to boil water, but to at least heat it to above room temperature. Those of you who have solar water heating will know it doesn't take direct summer sunlight to heat water in an enclosed container significantly. It could be similar in construction to the double-skinned tubes of most modern solar water panels you find on a roof. But you just put it on the window sill. I should patent that, but couldn't be bothered.

I thought solar kettles did exist? or was it solar cookers.

Just checked they do exist...

 

[rich p]

As a plumber in a previous life I would strongly recommend never drinking from the hot tap.

My Dad used to say the same but I thought it might be okay if subsequently boiled?

 

[mickle]

My Dad used to say the same but I thought it might be okay if subsequently boiled?

Depends on your system. If it's a modern combi, probably ok. But with a HW cylinder, unless you are 100% happy with the cleanliness of your loft I just wouldn't. We found a dead pigeon in a tank once. It was very dead and no one had noticed.

I just think it's 'best practice' to not.

 

[User482]

As ever, a lot depends on the pan being used. The link posted used an (invariably thick) aluminium pan on the hob. A thin based hob kettle is far more efficient.
About a year ago I had a similar (industrial) problem to solve. Albeit with a 'coolant' (approx 98% water). So did some controlled tests with water and coolant. Using a direct flame on a thin walled container was around 10% more efficient than an element in a container.
I also discovered that the vapour produced from heated coolant has a similar odour to wacky-backy, so my results may be a load of b0!!*%ks

A lot also depends on the shape of the kettle, size of the heating element, the energy mix in the national grid, the age of the microwave...but on average, I doubt there's any great difference in primary energy required to heat water either by an electric or gas hob kettle.

I assume that your experiment was looking at primary energy - electric elements are 100% efficient.

 

[Archie_tect]

New potatoes for salad or old ones for mashing?