Big Green: Heat pumps

[Barrie Moore]

  It is still necessary in an area where you still accept British 
Imperialism for we Brits to teach you Americans how to speak English 
correctly.  British Thermal Units (BTU's) can lead to confusion when 
talking about power particularly where electricity is involved. We 
now use kiloWatts to rate diesel engines, boilers and electric 
motors. KiloWatts do not have a temperature, they are a measure of 
power. This is where  British Thermal Units can give a bum steer. 
Equally, over here, when you mention kiloWatts most people think you 
mean electricity.  Any debate which confuses heat with kiloWatts is 
going to lead to talking at cross purposes and utter confusion. Where 
you get your kiloWatts from is important because electricity is much 
more expensive per kiloWatt than one sourced from the ground or from 
burning. "Thermal" kiloWatts  are easy to obtain with electricity and 
we all like the convenience of our washing machines, electric power 
showers, dishwashers and kettles. Heat pumps are different and use 
the expensive electrical kiloWatts to alter the low grade "thermal" 
ones  into high grade thermal ones. COP's of more than 4:1 are 
possible if you do not have a huge temperature lift . Using the 
ground as an energy source avoids the confusion of high temperatures 
being the only source of energy (kiloWatts) and all you AC engineers 
already know how much energy can be obtained from a ton of ice.  So 
the correct term is GSHP  and your homework is to tell me how many 
kiloWatts in a tonne of ice ?