Finally off gas! Well, Almost Finally.

Friends, yesterday was a happy day. Two technicians finally removed our gas hob and installed a new induction hob.

The gas oven and grill was replaced last week, and so this was the last step in a journey which has taken nearly four years.

And finally, we have no need to burn gas in this house ever again. I feel emotionally exhausted.

The Journey

The household’s smoothed daily gas consumption (kWh/day) along the journey is shown in the graph below.

Click on image for a larger version. Based on weekly readings of the gas meter, the graph shows Gas consumption in kWh per day for the last four years years, with the time-axis showing the number of days elapsed since the start of 2019. The data are averaged over 5 weeks to smooth out the noise. The pink boxes show the dates of key interventions which affected gas consumption.

Back in 2018/19 peak mid-winter gas consumption was over 110 kWh/day. This fell to first 70 kWh/day in 2019/20 and then 50 kWh/day in 2020/21.

In August 2021, the gas boiler was replaced with an Air Source Heat Pump, and since then we have just used gas for cooking – using an average of just over 1 kWh gas/day.

The graph also shows the heat output of the heat pump over the winter of 2021/2022.

The graph below shows details from the graph above.

Click on image for a larger version. Details of the graph above showing periods where gas usage was low.

Looking at summer consumption, back in summer 2019 (with my son and his girlfriend staying with us) we were using gas for hot water and cooking and our usage was around 6 kWh/day. In summer 2020 (with just my wife and I in the house) this fell to ~4 kWh/day.

Since 2021, we have used gas solely for cooking, an average of just over 1 kWh gas/day. Combined with the heat pump output of roughly 3 kWh/day for domestic hot water, this roughly matches the 4 kWh/day of gas consumption we used back in 2020.

Today’s step corresponds to Day 1360 and I have presumed to fill in ‘zeros’ ahead of time out to the end of the year.

In terms of carbon dioxide emissions the graph below shows that 3 tonnes of carbon dioxide that the house used to emit, is now finally falling to exactly zero.

Click on image for a larger version. Cumulative emissions of carbon dioxide from burning gas in the house. 

What’s wrong with ‘cooking with gas’?

Fundamentally, cooking with gas is a barely-evolved version of cooking on an open fire: it releases carbon dioxide and toxic pollutants (NOx) directly into our kitchens – a critical issue for anyone with asthma or children.

Although each installation differs, careful measurements reveal that domestic gas installations typically leak around 1% of the methane gas they consume – which practically doubles the global warming effect of using gas.

Gas cooking also wastes a large fraction of it’s embodied energy heating the room  – with typically just 40% of the gas’s energy being delivered to the food in a saucepan.

Click on image for a larger version. Left: measuring the rate of heating of 1 kg of water in a saucepan on a gas hobRight: the equivalent measurement on an an induction hob. The lid was kept on through the experiment except for occasional stirring, and the temperature was inferred from the average temperature of two thermocouples.

The graph below shows the rate at which 1 kg of water is heated on a gas hob and on our new induction hob. The effective heating power is a factor 3.6 larger.

Click on image for a larger version. Measured rate of heating of 1 kg of water in a saucepan on a gas hob and an induction hob. The induction hob heats the water between 3 and 4 times faster than the gas hob.

What’s so good about induction hobs?

Fundamentally, the key advantage of cooking with electricity is that the electricity can come from any source, including solar PV or wind. This afternoon, as I carried out the heating experiment on the hob, the electricity was being supplied entirely by the Sun.

Installing this hob means that we have finally broken this archaic link where ‘cooking’ implies that something must be burned and carbon dioxide emitted.

Induction hobs – aside from being quick and powerful – also combine features which gas cookers never could – such as temperature-related feedback control.

And it’s not just hobs: we have also replaced our cooker, and it was such a blessed relief to get rid of that appalling gas oven. The gas oven spewed it’s exhaust gases (steam and CO2) into the oven chamber itself meaning that they had to be continually cleared out  – wasting lots of energy heating the kitchen.

Now having a high temperature in the oven no longer means that the kitchen temperature needs to rise also!

Michael: what did you mean by ‘Almost’ off gas?

Friends, nothing in life is easy.

In order to change the cooker and hob I needed to have the backing of my wife who, while not hostile to my endeavours, does not share my enthusiasm.

And as a quid pro quo for the purchase of the cooker and hob from our joint savings, my wife suggested that we retain a gas fire in the front room.

I had planned to get rid of the gas fire – which we have not used for a year or more – and have the gas supply cut off, saving the standing charge of around £98/year. But my wife suggested that we may have power cuts this winter – and she has a point –  and that having more than one kind of heating might be useful.

So for another winter season we will retain the possibility of burning gas.

In case you care, this is what we bought.

Click on image for a larger version. Features which helped us choose our particular models of cooker and hob. For the hob we liked this simple way of setting power levels rather than having to repeatedly press a button.  For the cooker, we liked the way the controls recessed into the panel for cleaning.

My wife and were both unfamiliar with cooking with electricity and so bought mainstream models from Bosch on the principle that Bosch probably know what they are doing better than we do.

For the hob, my wife was concerned that the controls might be fiddly to use if we had to repeatedly press a “+” or “-” button to set a cooking level.

To avoid that situation we picked a model (Serie 6 PXE651FC1E) in which the cooking power is set by first selecting the relevant control area, and then touching a point on a scale: based on our experiments this afternoon, this works as sweetly as we had anticipated.

For the cooker, we chose a model (Serie 4 MBS533BS0B) in which the knobs could be recessed because that seemed very pleasing.

On balance, we thought both these items were very expensive for what they were and there are probably much better bargains to had.

10 Responses to “Finally off gas! Well, Almost Finally.”

  1. Gavin Says:

    Good job!

    The gas consumption graph is very instructive and I will definitely share it with my parents – both of whom I’m trying convince to adopt an air source heat pump and solar array.

  2. Alan Pike Says:

    I am envious of your progress, but here’s a question. Will caste iron pans work your induction hob? I use them in preference to the teflon-coated variety and saw someone giving away their caste iron cookware after purchasing an induction hob.

    • protonsforbreakfast Says:

      Alan

      I just tested and the induction hob works fine with cast iron cookware.

      Try testing your cookware with a magnet: my understanding is that if it’s magnetic, it will be fine.

      Best wishes

      Michael

  3. daviesrv Says:

    Well Done that man.

    I can’t quite leave gas yet. It is still so cheap, compared to buying electricity.
    However, when the sun shines. I do.

    We’ve got about 3kw of solar, and 5KWh of battery.
    For hot water, depending on the sun, we can switch between combi gas and electrical immersion.
    The immersion consists of two tanks, one 20l , and one 200l. Most times only the 20l is heated up.
    For heating, we have a stove in the lounge and we use wood from our woodland (1 acre). The stove is ample.
    However, we have just replaced one of the gas radiators, with a dimplex quantum storage radiator, which we can charge up if there is afternoon sun.

    There is an app that controls and displays everything (via Node-Red), and for anyone else, you can use a selection of commands via Alexa.

    We use an air frier, as a mini oven, along with a slow cooker, almost all the time.

    What to do in winter???
    Something windy would be good.
    Fridges are a bit of a pain………

    • protonsforbreakfast Says:

      Davies RV – Hi thanks for your comment. It makes me reflect on just how almost every home is unique and needs unique solutions. In particular:

      * If you have woodland that you can sustainably crop then this is a near carbon neutral way to get heat.
      * Using solar with a storage heater is a great idea which I have not heard of before.
      * Using mini-versions of cookers is likely to be much more efficient than the giant oven I have just bought!
      * In Winter: If you have the space, could you install a 5 m diameter wind turbine? As an alternative, have you tried signing up for Ripple’s next project (https://rippleenergy.com)

      In any case – every best wish with your endeavours!

      Michael

  4. Rob Says:

    After the installation of a ground source heat pump our gas bill was dominated by the standing charge, so I replaced the gas hob with an induction one and had the gas meter removed. (The oven was already electric).
    In the event of a lengthy power cut I can use the old gas fire with a camping gas bottle or even remove it and light an open fire in the original fireplace. The chimney is draught proofed with an easily removable wool pad.
    Many people I speak to seem to overlook that their gas/oil fired central heating also won’t work if there is a power cut!
    The induction hob is so much better than its gas predecessor (quicker to heat and easier to control) that I wish we had bought one earlier. It is also satisfying that in brighter weather we run it for free on our solar power!

  5. David Cawkwell Says:

    Might I suggest changing the jets on the gas fire if possible to propane and keeping a bottle of propane for the gas fire then cut the gas supply off saving the standing charge.

  6. eenjones Says:

    Congratulations on becoming effectively gas free!

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