How Heat Pumps work

Heat pumps are common

Electric heat pumps are the essential part of standard household equipment:

  • In fridges, a heat pump moves heat from inside the fridge into your kitchen. That’s why it’s good to have space around your fridge. This space allows the heat extracted from inside the fridge to move away from the fridge.
  • In reverse cycle air-conditioners, the heat pump cools a room by moving heat from the room to outside the house. When you reverse the cycle, the heat pump heats the room by transferring heat from outside your home to inside the room.

Heat pumps are efficient

Heat pumps use electricity to run a fan and compressor – and can be amazingly efficient. A high-performance residential heat pump can use one unit of electrical energy to move six times as much heat energy into your house, an efficiency of 600%.

By comparison:

  • Electrical heaters have an efficiency of 100% as they can convert all the electrical energy into heat, and
  • Gas heaters have an efficiency of between 50% and 95%, as some of the heat generated heats the house exterior.

Heat pumps for hot water

Here is a description of one sort of heat pump and how you can use it to heat your hot water. With this setup, you run the heat pump when the sun is up, powering the heat pump with electricity from photovoltaic solar panels. After installing the panels and heat pump, you heat your water for free, generating no emissions. 

How a heat pump works to heat water

A heat pump can heat your hot water by moving heat from the air outside your house into your hot water tank. Your heat pump will have:

  • A refrigerant: The heat pump has a refrigerant, i.e., a liquid that boils at a low temperature like minus 26 C.
  • An electric fan: The fan warms the refrigerant by blowing air from outside your house over a heat exchanger, which warms the refrigerant. While the air temperature is above minus 26 C, it will heat and boil the liquid refrigerant in the evaporator.
  • An Evaporator: In the evaporator, the heated refrigerant evaporates, becoming a gas as the external air heats it. It evaporates like water becomes steam in a pot on the stove. As the boiling point is so low, e.g., minus 25 C, it will work even on a cold day when the air temperature is 5 C. Note that the fan works longer to boil the refrigerant on a cold day.
  • A Compressor: A valve closes, shutting the refrigerant gas in the compressor where a pump compresses the air. As the pressure builds, the gas gets hotter, just as a bicycle pump gets hot as you pump up the tyres. The gas can heat to 95 C.
  • A Condenser: The hot, pressurised gas then passes its heat, via another heat exchanger, to where you want it, to the water in your hot water tank.In doing this, the gas cools and condenses into a moderate temperature liquid, still under high pressure.
  • An Expansion Valve: The expansion valve opens, and the cooled liquid moves from the high-pressure condenser into the evaporator at normal room pressure. The refrigerant is back where it started, a liquid ready for heating and evapourisation, ready to repeat the cycle.

So, you can harvest heat by repeatedly boiling a liquid, collecting the gas given off, and compressing the gas.

Further information

Updated: 24 Jan 2022

Australia’s strong sun

Australia could become a renewable energy superpower.  One factor behind this is that Australia gets stronger sun than most developed countries.

Two world maps superimposed

Here is a strange map that demonstrates this.

It is two maps superimposed on one-another. The first is a normal map of the world.  The second map shows, for each point on the first map, where you would be if you drilled straight down through the centre of the Earth to the other side.

The closer a place is to the equator: (1) the more the sun is directly overhead, (2) the more sunshine it gets, (3) the more electricity is generated from each solar panel, and (4) the cheaper it is for that place to generate electricity from the sun.  This is ignoring other factors like how cloudy a place is.

From the map you can see that:

  • Australia is closer to the equator than the developed countries in northern Europe, northern Asia and northern America.
  • Northern Greenland, Canada, Alaska and Russia are as far from the equator as northern Antarctica
  • Melbourne is as far from the equator as southern Spain, so most of Australia gets stronger sun than Spain and most of Europe.
  • Northern Australia is as far from the equator as the border between the Sudan and Egypt.
  • The southern border of the USA is about the same distance from the equator as Port Macquarie (half way between Sydney and Brisbane). So northern Australia gets more sun than the south of the USA.

Manchester in England is as far north as Macquarie island is south

Here is another way of understanding how strong Australian sun is, compared to Europe.  People often think of Macquarie Island, which lies far south of New Zealand, as being in the Antarctic.  Well Manchester in England is as far north (latitude 54 degrees north) as Macquarie island is south (latitude 55 degrees south).  Northern Europe gets very weak sun and if it were not for the Gulf Stream, much of Europe would be very cold.

Australia has quality solar resources

So, considering only the factor of sun strength (closeness to the equator), Australia has better solar resources than most developed countries – and we have other advantages too, which mean that Australia could become a renewable energy superpower.

Warm is Not Cool: A Musical Protest


A 2016 and 2019 Musical Protests Against Inaction on Global Warming


Our long-awaited first public outing was on Sunday 19 June 2016.

A marvellous experiment in public protest, inspired by the New Orleans brass bands, the English football crowds, and Brazilian samba.  We brought our delicious hybrid to the streets.

It was highly enjoyable, highly effective and downright dead, dirty funky. The three contingents of voice, horns and drums intersected in every cool way possible as we protested the woeful lack of attention in these election weeks to the elephant in the policy room: CLIMATE CHANGE.

To get people started, we rehearsed in public on the steps outside the Victorian State Library.  Here we are, learning and brushing up our songs, chants, and grooves.

Video 1: (1) watcha gonna do (2) Warm is not cool

After the warm-up,  we strutted our stuff at the old shot tower in the Melbourne Central Arcade.  (Sorry, you may need to be owned by Facebook to see the next two links.)

Video 2: (1) warm is not cool (2) watcha gonna do

Video 3: (1) warm is not cool

Later we were in the Melbourne City Square

Video 4: (1) warm is not cool (2) Whatcha gonna do

Then we did our thing in Federation square.
And called it a day.

Warm is not Cool: The Sequel: 26 June 2016:

Video 5: In Melbourne Central again: (1) warm is not cool (2) Whatcha gonna do.

Vote the bastards out: 2019

We sang this in the streets prior to the 2019 election – to no avail.

Vote the bastards out: Spookey Men’s Chorale

The songs and chants: Lyrics and tunes

Not too many words.  Lots of repetition, harmony and jive

****** Song: Warm is not cool

You can hear this on the sound cloud links and videos

Warm’s not cool

Warm is not cool
Warm is not
Warm is not
Is not

Yo de aye
Warm is not cool

Did you know that’s the case so
We got to fix up this place

We don’t want to mess up the future

***** Song :  A message to you Turnbull

You can hear this on the sound cloud links and videos

Stop your messing around
Better think of our future
Time to straighten right out
This problem in town

Turnbull, a message to you Turnbull
, a message to you Turnbull
, a message to you Turnbull
, a message to you Turnbull

22 percent of the reef is gone
Turn the coal off.  Turn the solar on

***** Song 3: Malcolm

You can hear this on the sound cloud links and videos.
Each part: bass, mid and top is separate on sound cloud.

Malcolm Turnbull’s got a very nice face
So let’s find him a lovely job in another place

***** Whatcha gonna do:  Call and Response Chant

Whatcha gonna do                  What
When the world gets hot      What
Whatcha going to do               Whatcha going to do
What                                                  When the world gets hot
What                                                  Whatcha going to do

Then Repeat

Try this chant while listening to the above video of us outside the State Library.

***** Chant: Coal Don’t Dig it

Coal don’t dig it
Leave it in the ground
You’ve gotta get with it


Stephen Taberner taught us these songs and chants

He knows how to work a group!
Here he is leading the Spooky Men’s Choir at a folk festival in Shrewsbury, England.  Good song.  You might even laugh.

Another top song

We Are Not a Men’s Group – The Spooky Men’s Chorale

As you might be able to tell, I’ve borrowed a lot of these “dirty funky” words from Stephen’s event promotion.

Andrew Gunner

A solar-powered winery on Sikinos

A remote winery on the island of Sikinos in Greece has a spectacular view and more.  It has solar panels on the roof and battery storage, along with the expected large stainless steel wine vats.  Across the world, it’s happening more, away from the grid, it’s economical to be self-sufficient.

The winery is 2.5 kilometres away from the main village, perched high over its terraced vineyard with views of steep island peaks. There’s a tiny church on one peak and, out of view in a valley below, there’s an ancient Roman temple that became a church.  The wine-dark seas of Odysseus are spread in front of you, with islands dotting the broad sweeping horizon.  You can walk the old footpaths of Sikinos, and most of the ancient agricultural terraces are crumbling, but at the winery, the terraces are in repair, and the vines thrive on the moisture from the morning mists. 

Manalis Winery Sikinos

Temperature, CO2 and Sea Levels move together

Sea levels, Carbon dioxide concentrations, and Global temperatures have moved together over the last 450,000 years.


The graphs show the movement over the last 420,000 years of:

  • Carbon dioxide concentrations in the air (the green line),
  • Global temperatures (the red line), and
  • Sea levels (the blue line).

The carbon dioxide concentrations have fluctuated between about 180 and 280 parts per million (ppm) over this period of 420,000 years, but in the last 50 years, it has rocketed to above 410 ppm. (See the red circle on the green carbon dioxide graph.)  

The sea levels and temperatures have moved with carbon dioxide levels in the past.  This suggests that the recent increase in carbon dioxide will lead to large rises in sea level and temperature.

The graph shows five periods of high temperatures. We are living in one of those warm periods. During the previous warm period, about 120,000 years ago, the temperature was a few degrees warmer than at present, and the sea level rose about 8 meters higher than the present – and carbon dioxide levels were a lot lower than they are now.

The work of Hansen and Sato provided the basis of this graph

(John Englander: Oceanographer)

Glaciers in retreat:

Glaciers around the world are in retreat. Out of 250 alpine glaciers studied, the Taku Glacier in Alaska was the only glacier not retreating until, in 2019, it too began retreating. At 1,500 metres thick, it’s one of the world’s thickest mountain glaciers, now retreating by up to 390 billion tons of snow and ice a year.

(This is a big deal. Mighty glacier finally succumbs to climate change: The Age: 8 Nov 2019)

A glacial melting feedback loop

As you descend from the top of a mountain, the air temperature will normally increase. Now, some alpine glaciers are 1,500 metres thick, and some Greenland glaciers are 3,000 metres thick. So, as these glaciers melt and the glacial surfaces drop, there are increases in the average air temperatures at the glacier surface.

Melting of the glacier———->A drop in the altitude of the glacier surface
* <———-A rise in average temperatures at the glacier surface

This temperature difference is the basis for a feedback dynamic that can amplify glacial retreat or growth. While this glacial altitude feedback loop is dominant:

  • a decrease in the altitude of the glacier’s surface increases the average temperature at the surface of the glacier,
  • this increases the melting of snow and ice on the surface,
  • this decreases the altitude of the glacier’s surface and closes the feedback loop.

This feedback loop is reversible, as if the glacier’s altitude increases, the average temperatures decrease.

The Extreme Ice Survey

The Extreme Ice Survey collects visual evidence of the impact of global warming on our planet, like time-lapse photos of the contraction of the glaciers.  Outside of the Antarctic, 95% of the world’s glaciers are retreating.


  • the film “Chasing Ice”, produced in cooperation with National Geographic. It won an Emmy award as an outstanding nature program, or
  • the TED talk by James Balog in July 2009.

Related pages

Updated 10 Nov 2019