Electric appliances powered by coal are better than gas

Even using predominantly coal-fired electricity, high efficiency electric heaters and cooktops are vastly better for the climate than using gas appliances. The idea gas is clean is a myth.

The gas industry has not been honest with politicians, regulators, their shareholders and you for decades.

The problem I'm talking about is not the same problem that the industry has recently been exposed over – the unaccounted-for releases of gas fugitive emissions from mining operations in exploration (the drilling of test bores), extraction and pipelining.

No, this little known problem is different and lies much closer to home. The fossil gas industry has been creating a large amount of greenhouse pollution in and around our homes and houses and through our roads and streets.

The pollution is methane being lost through domestic gas distribution networks. In South Australia, according to industry regulator ESCOSA, 8 per cent of all gas is being lost to the atmosphere in pipelines that connect the gas fields to our homes (see page 99 of this report). And the problem with losing such a large amount of methane to the atmosphere uncombusted is that unburnt gas is between 33 and 105 times more damaging to the climate than resultant products from combustion (predominately CO2).

According to NASA scientists over a 100-year timeframe fossil gas is 33 times more damaging than CO2 and over a 20-year timeframe a frightening 105 times more damaging. It is this '105 times 20-year timeframe' figure that really matters and is relevant to us in a world where we want to avoid dangerous climate change, a world that is on the brink of global warming tipping points.

Researchers and energy analysts at Zero Emissions compared modern electric appliances with their gas equivalents across a number of scenarios. The most representative scenarios are presented below.

Heating

We took the average gas heater (up to 40-years-old) that you can expect to find across a range of Australian houses. We ignored ducting losses (ducted units represent a large proportion of gas installations) and focused on the combustion flue efficiency which was assumed to be 70 per cent. We consider this figure to be conservative. We then compared this with a reverse cycle air conditioner with an energy efficiency rating known as a co-efficient of performance (COP) of 5. Around a dozen Japanese and Korean models exist at or about a COP of 5 and even go as high as COP of 5.4 (see the Energy Rating website for the models).

The result, taking into account greenhouse emissions from methane leaks on the gas distribution network, is that gas releases 13kg of CO2 equivalent per 1 kilowatt-hour of delivered useful heat, while a reverse cycle air conditioner produces just 170g to deliver the same amount of heat. The gas heater’s effect was 76 times more climate damaging than a reverse cycle air conditioner.

If you also include methane leakage upstream in the gas extraction field of 7 per cent (which is the average being observed in US studies with unconventional gas including coal seam gas), then delivering 1 kilowatt-hour of heat with gas would produce 26kg of CO2e. This is around 155 times worse than using an electric heat pump (assuming the average emissions from electricity provided from the NEM grid). 

Cooking

The team found that providing 1 kilowatt-hour (or 3.6 megajoules) of heat with a 35 per cent efficient gas cooker produces 27 times more CO2e (26kg) than an electric induction cooktop which releases just 900g. The worst scenario we tested for gas where upstream mining emissions were factored-in found that cooking with gas was 55 times more carbon intensive than cooking with electric induction and releases 53kg of CO2e per kWh of actual heat for directly cooking your food.

Hot water

In the most representative scenario delivering 1 kilowatt-hour of heat with gas produced 13kg of CO2e, a  result 61 times worse than doing the same with a hot water heat pump which produces 210g of CO2e for the same hot water (hot water heat pumps have to work harder than reverse cycle air conditioner space heating heat pumps due to the much higher 60-degree temperature they must achieve). 

In the scenario where upstream field methane leakage emissions were taken into account, gas water heaters produced 124 times the CO2e and 53kg of CO2e per kilowatt-hour of heat.

Conclusion

In no scenarios did gas produce less emissions than modern electric appliances, including the most conservative figures with lower (than realistic) levels of fugitives factored in.

Zero Emissions' research shows that it is well past the time when governments of all persuasions should be directing their climate incentive programs towards electric heat-pumps for heating and hot water as well as induction cooktops. The goal should be an eventual phase-out of the old legacy gas and inefficient electric resistance appliances.

For consumers, make your next appliance purchase electric not gas. Get a reverse-cycle air conditioner, induction cooktop or heat pump hot water unit, and save your wallet and the planet too.

Addendum: What if we used the outdated 2007 IPCC emissions factor for methane(CH4) and ignored upstream emissions?

Some readers have pointed out that the global warming potential I've attributed to methane is different to that used by the IPCC in their Fourth Assessment Report. However even if we use the outdated IPCC numbers on both 20 / 100 year averaging of the warming effect of methane, gas is still clearly the most emissions intensive option for households.

Gas Cooking gives 6.6 to 18kg CO2e/kWh which is 7 to 19 times worse than electric induction on grid average intensity electricity.
Gas Heating gives 3.3 to 9kg CO2e/kWh and is 19.4 to 52 times worse than heating on grid average intensity electricity.
Gas Hot Water gives3.3 to 9kg CO2e/kWh and is 15.5 to 42 times worse than heating on grid average intensity.

In every scenario, even if you ignore upstream field and distribution network emissions using modern electric appliances has lower emissions and is more environmentally friendly than heating with gas.

Matthew Wright is executive director of energy security think-tank Zero Emissions (zeroemissions.org.au).

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Additional information

Greenpower can make electric appliances zero emissions.
By purchasing government accredited 'Greenpower TM' all the above electric options can be made 100 per cent zero emissions and carbon-free contributing to the health and wellbeing of our society and a better future for all.

What are heat pumps?
Air is drawn into the heat pump via a fan into an evaporator containing a special type of refrigerant. The refrigerant has an extremely low boiling point of -26 degrees. The comparatively warm air that has been drawn in turns the refrigerant from a liquid into a gas. A compressor then compresses the refrigerant gas, generating heat that can heat your air or water until it is ready for use. Once the heat is drawn away, the temperature of the refrigerant drops and it returns to a liquid state to start the heat pump cycle all over again. Heat pumps operate like your fridge, it is much more efficient and easier to move heat, concentrate and upgrade it through evaporation and expansion of a refrigerant gas than it is to create heat directly.

What is Co-efficient of Performance (COP)?
Co-efficient of Performance, or COP, is the ratio of input energy required versus useful energy delivered. The input energy is measured at the socket. An average age ducted gas heating system with average air leakage and flue combustion efficiency would have an effective COP of 50 per cent with 25 per cent losses in combustion and 25 per cent losses in ducting. Many units are worse than this. While the best performing reverse cycle air conditioner on the market has a COP of 5.42 (see the government's energy rating website).

What are induction cooktops?
Induction cooktops consist of a hidden copper coil through which an alternating electric current flows. A ferrous magnetic pot (you can't use cheaper aluminium pots) produces eddy currents in the pot when the cooktop is turned on which then creates electrical resistance only in the base of the pot which in turn conducts its heat to your food. This process is very efficient and reduces the risks of burns and carbon monoxide poisoning associated with other kinds of cooking.