### Meaningless energy unit of the day: cups of tea

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To make an issue understandable to the average person we do not use scientific units. This would simply confuse the average bone headed human. No, we must do what we can to condescend, and use units people are familiar with.

It’s difficult for someone to visualize what a tonne of coal looks like. Instead it would be much wiser if we told people what the weight of a few million tonnes of coal would be in terms of blue whales, as the Guardian did recently.

Confused by the meaning of the blue whale unit?

How much do you think 58 blue whales weigh? I view myself as being at least semi-numerate and my day job is in marine biology. But if you were to ask me how much 58 blue whales weigh I would probably give an embarrassingly inaccurate answer, perhaps 10 or 1000% of the real value. So, why do journalists expect the average person to being informed by such nonsense?

And, here’s another one today: cups of tea.

According to STV, “Glasgow solar power project makes enough energy for 122 million cups of tea“.

Other than impressing readers with a big number, what is the point of this? And the news article gets even more ludicrous with this:

Housing bosses have calculated that the renewable energy project has saved more than 1,400 tonnes of CO2 – the same amount of CO2 as would be produced driving a bus 10,560,000 miles.

So, the solar panels produce enough electricity to make 122 million cups of tea and save as much CO2 as would be produced by a bus that would drive 10,560,000 miles. These figures absolutely nothing to me on first reading. So, why do journalists, who are tasked with informing the public, put such meaningless babble in front of busy members of the public who don’t have the time to convert absurd numbers into something meaningful?

OK. So, for the benefit of STV and anyone who cares about informative numbers, let me convert this into something meaningful.

In total, this project has saved 1,400 tonnes of CO2. The project began in 2011, so let’s say it has been running for 4 years. This would make it around 350 tonnes of CO2 saved per year. This is for 500 houses. So, that’s 0.7 tonnes saved per house each year. Now, let’s assume that are two people per house (STV adorn their story with a retired couple with a cup of tea). That would mean that the CO2 savings are 0.35 tonnes per person each year.

Per-capita CO2 emissions in Britain are around 7 tonnes of CO2 per year. This means that these solar panels have produced enough electricity to produced 122 million cups of tea, and will reduce the CO2 emissions of the residents by perhaps 5%. Which is more impressive, the former or the latter? And which statistic would be more helpful to the average reader?