This morning going into work, there was a segment on our local ABC about the energy saving light globes.
Yes, they save energy (between 60 to 80%, depending on the brand), but they also contain mercury and they have deleterious effects on some people's health, eg, those people with radiation sensitivity and some people with epilepsy.
Like many people we "greened" our lighting several years ago, but now we are having second thoughts.
So, I thought I'd do some calculations so we could compare the energy savings with the other environmental factors.
Assume an average household has about 20 lightbulbs (including outside lights, lamps and room lighting) - count them up and be surprised!
If these are all energy savers, which have about 5mg of mercury each, at any one time, there is about 100mg or 0.1g of mercury plugged into the light sockets. There are currently about 130,000 households in Canberra, so if everyone is using energy saving bulbs, there is 13,000g or 13kg of mercury plugged into our light sockets in Canberra alone, not counting the amount used by business and government.
Across Australia, if everyone used energy saving bulbs in their households, we'd have in excess of 800,000g or 800kg of mercury. And that's not counting businesses, schools, government, hospitals, etc, etc. That's a lot of mercury to dispose of safely!
Now to the energy side of the equation. Assume each household uses 4 lights for 4 hours each day, amounting to 16 lightbulb-hours. If these are (on average) about 70W bulbs, each house would use 1.12 KWh each day for lighting or 408.8 kWh each year. If the energy saving bulbs save, on average, 70%, the energy saving per household each year would be 286.2 kWh.
In Canberra, this would save about 37.2 GWh each year. Across Australia, it would be more like 2346 GWh. That's a lot of energy!
It takes about 1 tonne of coal to make 2500 kWh of electricity. So, each household using energy saving bulbs would save about 114 kg coal. Across Canberra, this would be about 14,882 tonnes of coal. Across Australia, it would be 938,700 tonnes of coal. Not to mention the water and other resources required.
So, at the end of the day, in order to light Australia's households, we have over 800kg mercury vs nearly 940,000 tonnes of coal.
I'm really not sure how to balance this equation. It's a lot of mercury to dispose of safely and it's a lot of coal to dig out of the ground.
Because of the potential health risks, we've decided to use the old incandescent lightbulbs as long as possible. But we minimise our lighting and strive to have only one light on at a time at night, maximum two. I'm not absolutely sure we are doing the right thing. But then I'm not absolutely sure that the new energy saving light bulbs are the right way to go either. So, it comes down to a personal decision.
Would love to hear your thoughts on this one.
love and light