In many countries around the world gas is being used as a “transition fuel” to reduce the GHG (GHG) emissions of buildings, so should we being using gas in Kiwi buildings to reduce our environmental impact?
What is the comparison between different fuels GHG emissions?
These emissions vary considerably between different countries. Therefore, heating systems that make perfect sense in one country may not make nearly as much sense in another. For example, in Australia if a building or home uses electricity instead of gas for heating and domestic hot water (DHW) it will be emitting up to 4.7 times more GHG than directly burning gas, in a boiler or instant water heater.
In this context the logic of using efficient gas appliances makes reasonable sense, especially as we transition to even more sustainable and lower carbon heating options in future.
If we apply the same logic to NZ do we get a similar outcome?
In NZ, natural gas has emissions of 0.195 kgCO2e/kWh. Whilst our electricity is around 85% renewable and so has emissions of oly 0.097 kgCO2e/kWh. This makes electric appliances 50% less carbon intensive than using a gas appliance.
Therefore burning gas, no matter how efficient the gas appliance, has at least twice as much negative environmental impact in New Zealand as using readily available alternatives.
Electricity is the clearest direct alternative to gas (natural and LPG), with distribution throughout both islands and GHG emissions half that of burning gas in NZ.
Combining electricity with a high efficiency heat pump makes the numbers even better, with average COP of 3 and up to 5 for a CO2 hot water heat pump. With the choice between standard electric hot water cylinders and hot water heat pumps, most heating and DHW loads in a home can be met without using gas.
The second widely available and extremely low carbon option is wood pellets. In NZ these are 100% made from waste wood (sawdust & wood shavings mainly), with carbon emissions at a tiny 0.003 kgCO2e/kWh. This means that burning wood pellets instead of gas in any building in NZ reduces the GHG emissions by an impressive 98.5%.
Wood pellets are made in Taupo, Nelson and Invercargill, by three companies with national distribution networks and active market competition. There are a large number of distributors of high quality, European pellet fires and pellet boilers that can fulfil the space heating and DHW loads of any commercial building or home. These systems can be as easy to use as a gas boiler and are very widely used in very demanding markets such as Germany, Austria, France.
Ask yourself, based on the GHG reductions we have agreed to as a society plus the easy availability of alternatives is there any thoughtful reason to be specifying a gas hot water or heating system in any home or building?