Electricity and heat

By Marcus Wilson 06/07/2011 10


There’s an advert that’s well-featured on the television at the moment for a plug-in wall-mounted heater.  As part of the advert, the product is described as ‘efficient’.  Now, I’m not at all saying that these heaters aren’t a good purchase, but a bit of physics tells me that this statement about efficiency doesn’t really mean very much – all heaters that work by converting elecricity to heat are going to be 100% efficient.

Energy comes in various forms. There’s electrical energy, movement (kinetic) energy, sound energy, gravitational potential energy (the energy stored in a hydro lake), light and heat, just to name some. Energy can convert between forms, but is always conserved – you can’t create energy out of nothing (at least, not for long periods of time, but I’ll leave quantum electrodynamics aside hre) and you can’t destroy it.   In which case, you might ask the question, "If it’s never destroyed or used up, why do we have to pay for it?"

Unfortunately, with energy, it is easier to convert it in some directions rather than others. Formally, this is encapsulated with the second law of thermodynamics – that entropy (‘disorder’) increases with time. Take friction for example. A rolling car on a flat road will eventually come to rest because of friction in the moving parts of the car, between the tyres and the road, etc. (and due to air resistance). Here, the movement (kinetic) energy of the car has been converted to heat energy.  That process happens naturally on its own. What doesn’t happen naturally is that a car sitting stationary on a flat road starts moving, because heat in its parts turns itself into kinetic energy.  Energy does not flow naturally that way.

Essentially, the second law of thermodynamics tells us that producing heat is really straightforward. Take just about any physical entity containing some form of energy, and it will eventually generate heat. It’s not difficult.  So, our plug in wall-heater, is designed to take energy from the power station (transmitted through the electricity grid) and turn it into heat. This it can do perfectly; every bit of energy that gets to the heater through the electricity supply gets turned into heat.   (Contrast that with a light bulb, where some gets turned into light, and some to heat, or with your TV, where some goes to light, some to sound, and some to heat). So the heater is 100% efficient at converting electrical energy to heat energy.

 Just where that heat goes next is determined by your house design, particularly how much insulation is in the roof – hopefully it hangs around inside your house for a while, before leaving (still as heat).

And just to end, you can get more than 100% ‘efficiency’ though in electrical heating – namely the heat pump. In this case heat energy is transferred from the air outside (yes, cold air contains heat) and is pumped inside. This flow doesn’t happen naturally (second law of thermodynamics), and there is a cost you pay. You need to input more energy to get it to happen – that’s the electricity supply to your heat pump – but you get that energy back as heat as well, so you don’t lose out. 

So a claim of 100% efficiency for an electrical heater doesn’t mean a great deal – don’t take much heed of it when deciding what plug-in electrical heater to buy!


10 Responses to “Electricity and heat”

  • Interesting you talk about entropy, what about negative entropy and Schaubergers electric vortex ? I saw an interesting video of Albert Einstein confirming that relativity would not work without the Ether. Google it you will see that even the patent clerk confirms the Ether which has since been denied.

  • Hmm. Conspiracy theories again. What can i say? Come clean, and admit you’re right – indeed we scientists at the University of Waikato and University of everywhere else, and the governments of New Zealand, US, Russia and Sierra Leone to name a few have known for the last 80 years how to make energy for free, but we’ve been hiding it from everyone for our own evil purposes. Why do you think your taxes are so high – it’s because it’s costly to go around stamping out every trace of scientific evidence. Why are universities wanting to recruit so many students? It’s because it takes a lot of manpower to do this task of suppression. And, by the way, free energy isn’t the only thing we suppress. You might wish to know that our prime minister (and several others – but not including Julia Gillard – she really is a human) is a robot controlled by the Venusian mother-ship in high-altitude earth orbit and that Hamilton City Council has been pumping nuclear waste from its secret weapons programme into the Waikato for the last 20 years and calling it ‘fluoridation’.

    If you really have a method of producing free energy, GO AND DEVELOP IT. There will be a BIG market for it. You will make lots of money.

  • Haha Marcus your good,
    have been reading some of Tesla’s work lately the war of the currents, not standard electron theory but radiant energy and high frequency currents, very interesting how he converts standard energy with disruptive discharges, stepping up the potential and the frequency. This from the man who gave us the Ac system, car ignition system, Radio, remote control, wireless transmission yawn bla bla.

  • Haha Marcus your good,
    have been reading some of Tesla’s work lately the war of the currents, not standard electron theory but radiant energy and high frequency currents, very interesting how he converts standard energy with disruptive discharges, stepping up the potential and the frequency. This from the man who gave us the Ac system, car ignition system, Radio, remote control, wireless transmission yawn bla bla.

  • Back at you ardvark
    Thats cool man there is no ether but there is dark energy, which apparently all the smart and wonderful minds have no idea what it is.
    From Plato to Tesla the universe has been full of energy, they called it the aether, so now we have a universe full of energy but it is definately not the aether (according to theory which is theory), but we can safely call it dark energy. Sounds just like a name change to me. Can you explain this for me.?

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