September 2015

Vehicles28 Sep 2015 09:43 am


The emerging scandal at Volkswagen and Audi is raising the question of whether “clean diesel” is an oxymoron. I have shone the spotlight on this question before, and the answer for South Africa is: “Yes.” Certainly for city drivers, “clean diesel” is a contradiction in terms. You can read my article for the Mail & Guardian on this topic here.

The South African authorities have launched an investigation into whether VW’s rigged engine software was used to circumvent South African standards and the carbon tax on vehicle sales. Regardless of those results, all diesel vehicles pollute more in South Africa than in the US or Europe. Our standard diesel fuel has 10 times the sulfur found in European diesel and 33 times more sulfur than in American diesel. Paying more for low-sulfur diesel just adds to one problem while partially solving another; though engine emissions are better, 10ppm and 50 ppm fuels have a much higher coal content, contributing to higher emissions at Sasol’s refineries. You can find advice on choosing the fuel and engine suited to your driving here.

Global Warming &Hot Water &Solar10 Sep 2015 12:44 pm

Solar Hot Water Panels

The Highveld winter drought broke this past weekend with a two-day deluge. The soil needed the rain, but when you ordinarily heat your water with just the sun, it’s painful to switch the power on for the geysers. I cheered myself up with the thought that I could check how much electricity I would be using without my solar hot water system.

My home’s consumption for this sunless Saturday and Sunday averaged 30.5 kilowatt hours per day. In comparison, on the four previous weekends I was using 12 kWh/day. Assuming that hot water accounts for the difference, the sun ordinarily saves me 18.5 kWh/day, cutting my electricity bill by more than half. (I monitor my consumption using a customised spreadsheet you can download here.)

This is very close to the 19 kWh in savings I calculated in a different test here. My solar system is large — with 3 flat panels, 1 evacuated-tube panel and 600 litres of storage — and the rest of the home is very efficient, so I couldn’t promise such dramatic results on every house. But this gloomy weekend tells me that solar is saving me at least R9,000 a year, not to mention keeping 5 tons of carbon dioxide out of the atmosphere.

That’s a sunny thought no matter what the weather.