Gas – is it a natural fit for buildings?

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(Note: This article has been updated to correct leakage rate that cause the net climate effect of gas to double. The leakage rate is 2.6%, not 1% as originally published)

According to the Department of Climate Change and Energy Efficiency website, old electric-element-style hot water systems (that about half of households still have) “produce up to three times the greenhouse gas emissions of low emission technologies such as gas, solar and heat pump systems.”

The website recommends, that “changing your electric water heater for a low emission gas, heat pump or solar system, you can reduce your energy consumption, cut your greenhouse gas emissions and save money on your power bills.”

As far as heat pumps go, and electric or heat pump boosted solar, it’s hard to argue. But for fossil gas appliances, that “low emissions” tag is plain wrong. Now, we could just criticise it by asking whether “low emissions”  is good enough. Many think there’s enough scary climate science reports to mean that “low emissions” halfway measures are not good enough.

It’s true that at the point of combustion, fossil gas produces about half the emissions of coal for the same amount of energy. We could debate about whether the emissions cup is half full or half empty at this point, but that would be a diversion. In truth, if you look past the point of combustion, the cup is overflowing.

Previously, Beyond Zero Emissions have pointed to the fugitive/migratory emissions from coal-seam gas as a big question for just how low the emissions of future (and some current) gas supply will be. This concern is now gaining mainstream attention, as evidenced by the ABC TV Four Corners program last week. It’s a serious worry, given that CSG is the fossil gas industry’s future.

Beyond Zero Emissions’ Buildings Plan researchers have put together a short briefing paper drawing on the available research into the various problems of using gas, and conclude that gas use should be phased out (in buildings in particular) – based primarily on its climate impact.

The key reason is that all gas networks leak, not just at the well head. The only question is how much. There is some limited data out of South Australia that suggests the gas networks’ leakage there is in the order of 7%, whereas official government figures put it at around 1.5% nationwide. In reality, in most areas, it’s probably somewhere in between.

Fossil gas is methane. The 20-year Global Warming Potential (GWP20) of methane is currently understood to be about 105 times that of CO2. The next 20 years – the next 10, even – are crucial if we are to avoid climate change, so there are very good reasons to consider GWP20 rather than the more common GWP100.

And with GWP 20, it only takes about 2.6% leakage to effectively double the net climate effect of gas. That is, the 2.6% that would be leaking as methane would have the same warming effect as the other 97.4% being burned, over the next 20 years. This doubling of emissions already makes fossil gas roughly equal in impact to black coal.

A recent study in Manhattan went beyond the gas industry reporting/estimates of leakage (which are said to be 2.2% there), but measured the methane levels around Manhattan with a cavity ring-down spectrometer.

This is the same instrument and method used by Southern Cross University researchers who recently uncovered alarming levels of methane around the Tara CSG fields in southern Queensland. Methane disperses quickly, so locally elevated levels are significant and indicative of a strong nearby source. The Manhattan study found gas networks’ leakage to be around 5%, according to the researchers.

For Australia, even the official 1.5% leakage rate gives fossil gas no great climate advantage over coal, on the timeframe we think is important. We could do more work to find out what the real leakage rate is and if it is higher.  BZE recommends phasing out all use of gas in buildings in a short (less than ten years) timeframe.

It’s still a challenge to supply all electricity with renewable energy, but we know that can be done. You can buy renewable electricity today; not so renewable gas. Supplying renewable bio-gas in large quantities is a very land-intensive process, and as far as methane leaks go, doesn’t solve much.

If you like to think in epochal terms, we’re looking for the beginning of a new one: the post-combustion era. “Re-inventing fire” as Amory Lovins has put it. Combustion (first wood, later fossil fuels) has been a fundamental constant in human society’s development. Is it possible to move beyond that yet?

For almost all of what is currently done by combustion, the answer is yes. Certainly in the case of home hot water, heat pumps (electric devices to harvest solar heat from the air) already outperform gas appliances. Reverse cycle air-conditioners (which are also heat pumps) do the same for home heating. Electric induction can generally cook as well as or better than gas stoves.

With any technology that carries some risk, we weigh the hazard against the benefits. For electricity – even 100% renewable electricity – there are still hazards and problems. But for gas, that balance has now shifted, especially as fossil gas supply is now moving to CSG. We’re seeing that the hazard is much greater than we once thought, and the benefit much less.

If DCCEE would just cease promoting new gas-burning appliances on its websites – or better, regulate to ban new gas installations – we would be getting somewhere. Ceasing gas use in buildings is one of the low-hanging fruit in a larger fossil fuel phase out. Fortunately, renewable energy and efficient electric appliances are up to the task.

Richard Keech works for Beyond Zero Emissions on the Zero Carbon Australia Buildings Plan, which is expected to be published in mid 2013. BZE has just released a 2-page briefing paper on the many reasons why they recommend no more fossil gas use in buildings, which is available for download here. Several of the points in this article are referenced in the paper.


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  • DHW

    Split electricity tariffs into elements that genuinely represent the costs of electricity delivery, ie. 1. energy at a price of average wholesale plus ~ 20% margin = about 8-10c/kWh. 2. Connection, overheads and peak use charge which varies on how much power you use during the peak and therefore your contribution to network augmentation.
    The effect of this is that energy use charges will fall by 60-70 and particularly when heat pumps are used, it will blow gas away for the cheapest way to heat our homes and water, not to mention running our cars. Time of use metering and storage both domestically and within the network will keep peak price penalties down, allowing us to increase energy flow without increasing the peak.
    This way, transport and heating can be de-carbonised at the same time as the grid.
    Sound good?

  • Ray Cowling

    Thank You Richard – this is my correspondence on the same issue:
    to Department of Climate Change and Energy Efficiency GPO Box 854 Canberra ACT 2601 Australia
    Dear Sir/Madam, you have at least two errors of fact on your web site, viz:
    “A gas-boosted solar water heater generates the least greenhouse gas emissions of any low emission water heater.” and
    “The most greenhouse friendly option for water heating is a gas boosted solar hot water system.”
    I pay a tiny additional charge to have wind energy derived electricity. Its availability should be trumpeted on your web site. Thus an electric booster can be the “least generator of green house gases.” and far better than gas which may come from fracking aquifers. When will the web site be corrected?

    reply from Department of Climate Change and Energy Efficiency
    The items you are referring to are based on the average carbon intensities for electricity and natural gas. They do not account for renewable energy contributions. It is accepted that where there is a significant renewable energy component in the electricity supply, electric systems such as solar-electric or heat-pump hot water systems will have lower running CO2 emissions. The National Construction Code contains a method of calculating the greenhouse gas intensity of a water heater based on the energy source. The comments on the web site reflect the most viable option for the average user. I hope this information has been helpful to you. Kind Regards, DCCEE

    • Alastair

      WHat a pathetic reply from DCCEE! ‘Oh near enough is good enough for us, we’re only talking to 22 million Australians here’.

  • Curly

    That Elgas ad at the bottom seems very inappropriate.

    • Giles Parkinson

      Hey Curly. The Google ad server chooses ads according to what thinks are the reading habits of the user. So it probably reflects more on what you read more than something about the website. When my daughter signs on, it’s all shopping ads!

  • John P Morgan.

    Some simple “in house” decisions can help too.
    I have so much free (off grid) solar electricity, that I do all my cooking electrically.
    My gas stove of 4.5 years has never been used.

  • David

    Both solar and heat pump systems are necessarily storage systems. Gas instantaneous hot water avoids the standing losses which are inherent in having 300 litres or so of very hot water standing around 24 hours a day. My understanding is that these losses represent something like 30% of energy requirements.

    You have also neglected the fact that coal mines also suffer from fugitive emissions of methane.

    I believe that instantaneous gas has lower overall CO2 equivalent emissions than most heat pumps (many have very poor COP)and probably lower than many electric boosted solar systems.

    For the time being, it would be better to get people off element type electric storage heaters by any means and just fix the gas leaks.

      Pure Solar without Added Electricity is the best option For heating water. Not heat pumps. They consume Electricity to extract the heat from the atmosphere.
      Item no2
      Methane from Coal mines can be extracted and used Commercially for the production of Electricity, Which could offset the energy costs to the Coal Mining Industry.
      Item 3
      Their is a way to produce Cooling and Refrigeration using solar technology if any one took it up.
      Item 4
      Instantaneous gas not a bad choice but Still produces Co2 even in lesser amounts So Pure Solar Alone seems the Way to go With larger capacities than now produced with.

      • Concerned

        Ron, how do you get hot water when the sun does not shine for days on the coast?
        I keep records, and you cannot rely on the Sun. In addition the usual models available due to design and cost do not work efficiently in winter.

        • We never have had the problem of cold solar hot water the worst it ever was at winter was warm after a week of rain .
          If you use water wisely and not stay in a shower longer than a minute it is long enough to get the grime off.
          I have installed a tempering valve which helps with not wasting hot water.
          We also have fitted those temp lights that tell you how your hot water is a great device from my friends in China. We have them on taps and the shower bought as a novelty at first but found they were excellent for older people.

          • Concerned

            Tempering valves are installed under the regs.
            And the rest is nonsense.

          • Dear Concerned.
            What I Should have Said We have Temperature sensitive mixing valve that prevents older people from being burnt that reduces the wastage of hot Water the bit about the temp lights is correct When down my way Please Visit and I will willingly show you.

    • It’s not possible nor economic to “just fix the leaks”, David. There are two different kinds of fugitive emissions. The kind you are obviously thinking of, those emissions that occur in the gas distribution network, are under-estimated by industry and industry are studious in avoiding accountability on them in terms of any CO2-e carbon price. Their logic goes, the emissions are so minor as to not warrant the cost of monitoring them so we base our fugitive emission estimates on industry assumptions about what they may be. We will never know if our assumptions are incorrect b/c we don’t comprehensively monitor for leaks in the network. Their cyclical argument defies rationality.

      The second kind of emissions, or the first in terms of occurrence, are the migratory fugitive emissions which occur under the ground as a direct result of the mining fracking processes. The emissions may surface from water bores on neighbouring properties or in water ways where the bubbling makes it apparent. The industry typically completely denies responsibility for these emissions on public land, never releases baseline testing for “before” levels of natural emissions and in the case of damage to private water bores trucks in clean water from elsewhere for the land owner (unreliably in many cases) but does nothing to mitigate the methane emissions effect on our climate.

      So David, the assumptions you have made are very inadequate indeed.

      • David


        virtually all of the gas currently used in Australia comes from conventional, deep underground sources where fracking is not involved. For local consumers, your argument is simply invalid and if the original article is based on this assumption then it is even less credible. The new coal seam sources will be predominantly for export and I agree that it would be better if it were left untouched but that is a different issue.
        Nevertheless, my “fix the leaks” comment was actually tongue in cheek because I understand quite well that plugging leaks in the distribution system is non-trivial.
        I see gas as a necessary bridging tool to an eventual renewables based system but until the coal generation is retired in favour of renewables, it remains perfectly acceptable. The gas distribution system already exists and is not going away anytime soon. Discouraging people from connecting to it is not going to reduce gas leakage by any significant degree. Discouraging people from getting off existing element type heating by not allowing them the cheapest, low CO2 option is counter productive.

  • Too Simple.
    It is Very Easy to have a look at nature and solve the Problem of Co2 ,s
    In caves their are Stalactite and Stalagmites they are formed through the action of water picking up atmospheric acids, an Co2 forming carbolic acid. In a weak form and dissolving limestone .
    So we should be able to bubble Co2 through lime scrubbers and end up with calcium carbonate a solid Safe and usable.
    Simple Science Learnt At School 50 years ago.

  • Jonathan Prendergast

    If methane leakage in our gas distribution systems is indeed unaccounted for and not included in Carbon Accounting methods including the NGA factors, then it needs to be. Indeed if it is as high as 1 or 2%, then it is a big issue.

    The big question is, is it really true? And how do we find out?

    There are many links in the article. I can’t see one for the ‘ official government figures’ of 1.5%.

  • Jonathan Prendergast

    I have done my own calculations.
    Firstly, a 40% efficient gas fired electricity generator sees a 44% reduction in GHG emissions. Higher efficiency engines/systems (CCGT, trigeneration) see much greater reductions.
    This uses the July 2012 National Greenhouse Account Factors. This already includes 1.32% gas leakage in the Scope 3 emissions.
    By my calcs, if it were 2.6% rather than 1.32%, this would increase GHG emissions of gas use by 13%. But a 55% efficient CCGT would still see a 54% reduction in emissions compared to Black Coal.
    From what I can see, you have made 2 errors. Firstly, you have not recognised that the NGA Factors already includes gas leakage, so therefore included in normal Carbon Accounting calculations.
    Secondly, while Methane (Gas) has a high GWP, it also has a high energy content factor. So a 2.6% GJ loss is only a tiny mass of methane. And we measure GHG emissions by mass/weight.
    Seems like you forgot to carry the one.