So far my blog has focussed on our electric cars. This is but one aspect of our impact on the planet, so I’ve started to look at what else I can do to reduce our carbon impact. But what areas should I focus on? It seems “obvious” at first glance that the transatlantic flight I took in summer (primarily for work, with a holiday added on) would be a leading culprit. Would investing in a battery for the house be worth it? How does food compare? What about the gas used to heat our house in winter? A new pair of jeans? God forbid, a new mobile phone! Where does it end?!

A sustainable amount of carbon emissions is 3 tons per person, according to the UN. At this level it is expected that the planet can cope, by absorbing carbon into natural sinks.

Using an online calculator from carbonfootprint.com, I could start to answer these questions. For comparison, the UK average is 6.5 tons per year. Here are some other figures to calibrate your carbon brain:

-Flight UK to Boston, USA: 1.5 tons

-Flight UK to Barcelona: 0.37 tons

-1000 miles in a diesel car: 0.35 tons

-a cup of black coffee, 21 grams, a cow-latte 340 grams. It’s the milk…

-2 passenger, 14 day cruise ship holiday: 5.3 tons (!)

My overall footprint in 2019 includes buying renewable electricity,* all water heating done by solar electricity, driving a pure electric car (virtually zero carbon – it needs almost no servicing, and the electricity to charge it is included in the domestic bill so the impact is the embodied energy, 8.8 tons, divided over 20 years), eating a “low meat” diet, a flight to the USA and a flight to Turkey, and incidentals like a mobile phone and some clothes. It totals 7.6tons, more than double the 3 ton target.

The surprise to me was that, after the flights, food is the biggest single contributor:

Reducing flights from 2019 will be easy, and I’d like to delve into the carbon emissions associated with food to see how accurate my estimate is. We’ll also use more renewable electricity for heating at home this winter by using excess solar generation. Next year’s target is more like 4 to 5 tons.

Clearly the changes I’ve made over the past few years, moving to EVs and insulating our house, have had a marked effect. Looking back at my bills, I was responsible for roughly double my current emissions, ten years ago.

* Footnote: electricity carbon impact. I originally dodged this one by naively assuming that through buying renewable electricity I can ignore it, or at least use a very low CO2 figure. Apparently this isn’t realistic. Our use is from our own PV, and grid with a significant amount used off-peak to charge the electric cars. Roughly 3000 kWh is EV charging off-peak, with a further 1200kWh from the grid. We generate around 3800 kWh from our own solar PV (we use roughly 60% of the energy ourselves)- this too has an impact, as the panels and inverter had to be manufactured and transported. PV is around a fifth of the impact of average UK grid electricity in 2019.

So I have adjusted the figures to include a mix of solar PV, 44g/kWh, the typical grid in 2019, 235 g/kWh, weighted using an off-peak 150g/kWh to account for our non-average use pattern; 170g/kWh.

These figures also give a basis to look at the cost-benefit of domestic battery storage, but that’s for another day…

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