One, two, three. What are we counting for?

I've written before about innumeracy, the inability to use numbers correctly. Recently I've been exposed to three cases of number abuse in different contexts. One of these is people with an agenda using a very large and apparently frightening number which actually means nothing much at all, one is people with a different agenda treating a large number as if it is zero, and one is a scientific publication using a number which is obviously and ridiculously wrong.

Anyone who has spent any time with forums and publications from the anti-medicine or anti-science worlds will know that (ignoring the pharmaceutical companies) two of the most evil corporations in the world are Monsanto and Nestlé. Monsanto because they are trying to own and control the world's agricultural production by patented genetically modified plants, and Nestlé because of the harm they do by distributing milk formula in third world countries.

California is currently in the grip of a severe drought, and as an Australian I am well aware of the threat caused by drought. There is a ghost town in Queensland that used to be the centre of a wool industry with twenty million sheep until a few consecutive years of drought wiped out the flock, the farmers, and the town. A recent piece of hysteria has focussed on water extracted by Nestlé for bottling. The horror was Nestlé paying $542 for 27,000,000 gallons of water.

27 million US gallons is a lot of water. To use the media's standard unit of measurement it is about 36 Olympic swimming pools. It is also about 67.5 seconds of California's average water consumption. That's right – if Nestlé stopped extracting water, California's drought would last for just over a minute less. I live in a small country town (population about 2,000) and the local dam supplying the town's water can deliver about 190 million US gallons per day for all uses (domestic, agriculture, manufacturing, river quality). In times of flood, the spillway can release about 56,000 million US gallons per day without water overtopping the dam wall. 27 million gallons is not really a lot of water.

The mighty Oberon Dam, capacity 11,888 million US gallons (that's 440 Nestlé units of measurement)

The next misuse of numbers is the assumption that the energy used by electric cars comes from nowhere. This seems to be a blind spot for those who think that all pollution from transportation will stop when everyone has a Tesla. (I'm mentioning Tesla specifically because there is almost a religious fervour about this particular car manufacturer. One ignored number related to Tesla is that Holden are closing their manufacturing in Australia because it is not economic to run a factory that produces twice as many cars each year as Tesla does.)

The most recent figures say that the combined annual consumption of petrol and diesel in Australia for passenger and light commercial vehicles is 23,519 million litres. (I know people are talking about electric semi-trailers but right now it seems that the weight of batteries needed to tow forty tonnes from Sydney to Melbourne might leave little over for the actual paying freight, so I'll leave those out for the time being.) Putting these numbers through a spreadsheet and mixing in the energy densities of the fuels shows that replacing them with electricity would require an additional 24,000 MW of generating capacity. That would require the building of more than seventeen black coal power stations the size of Mount Piper in New South Wales which supplies electricity to my town (and most of Sydney), or an additional eleven plants the size of Loy Yang in Victoria (Australia's largest power station). But wait! What about wind power? Providing the additional electricity would require 7.5 times the current installed wind generation capacity. These figures do not take into account losses through transmission or storage.

The short version is that we are a very long way away from everyone driving electric cars.

Here is a picture of the place that supplies the electricity to my place (and to Tesla charging stations).

The third abuse of numbers is sadder than the ones above, because it comes from a publication that purports to provide scientific news to the lay population. It promotes its publications heavily through social media and ran a story recently with the headline "This giant floating farm could produce almost 10 tonnes of food each year". The subtitle was "Fruits, vegetables and fish!" and the first paragraph teaser said "Architects in Spain have designed a three-storey floating farm that would help produce nearly 10 tonnes of extra food for Earth's growing population each year, without taking up any land or fresh water". You will notice that the figure "10 tonnes" appears twice so is not a typo.

Feeding the world's increasing population is certainly a problem, but to put the "nearly 10 tonnes of extra food" into perspective, Australia currently produces about 24 million tonnes of wheat alone each year. We even make about 340,000 tonnes of powdered milk, and export about 20,000 tonnes of seafood.

Numbers. They mean something and should be used with care.

This article was published as the Naked Skeptic column in the November 2015 edition of Australasian Science