In eco-impact, CFLs are greenest

Are compact fluorescent light-bulbs (CFLs) really as eco-friendly as advertised? There remain plenty of people who are still sceptical of those claims, but new research from Switzerland indicates that — when the complete environmental impact picture is considered — CFLs really are the way to go.

Scientists at the Swiss Federal Laboratories for Materials Science and Technology (EMPA) completed life-cycle analyses for four different types of lamps: the classical incandescent bulb, halogen lamps, fluorescent tubes and CFLs. They concluded that, after taking into account everything from manufacturing processes to electrical power sources to disposal methods, compact fluorescents come out the clear winner.

That finding helps bolster the case for efforts across Europe to ban and phase out the sale and import of low-efficiency incandescent light bulbs, more accurately known as tungsten filament bulbs. As of Sept. 1, 2009, new EU rules require a gradual phaseout of such conventional light bulbs; after Sept. 1, 2012, the sale of all types of such bulbs will be prohibited.

The measure has met with some resistance, in part from opponents who point out that CFLs contain environmentally harmful mercury.

However, EMPA researchers Roland Hischier, Tobias Welz und Lorenz Hilty found that the impact of CFL mercury on the environment, even if the bulbs are incinerated rather than recycled, is minimal compared to the pollution caused by coal-burning power plants.

Depending on whether it burns brown coal or anthracite, a power station emits some 0.042 to 0.045 milligrams of mercury for every kilowatt-hour of energy it produces. Therefore, a plant generating 1,000 megawatts of power releases 42 to 45 grams of mercury into the atmosphere every hour. By comparison, since 2005, CFLs sold in Europe may contain a maximum of only 5 milligrams of mercury. That means a coal-fired power station emits the same amount of mercury every hour as is contained in 8,400 to 9,000 energy CFLs.

The EMPA team found that, no matter what kind of light bulb, the total environmental effects caused by production was small. Using Switzerland’s power mix, that impact ranged from 1 per cent for incandescents to 15 per cent for CFLs. (The higher-efficiency lamps have a larger manufacturing-related ecological footprint because of the electronic circuitry they contain.) Based on the European power mix, those effects were even smaller: just 0.3 per cent and 4 per cent, respectively.

What that means is an incandescent bulb is more eco-friendly than a CFL during the first 50 hours (based on the European energy mix) to 180 hours (using the Swiss power mix) of use. After that, however, the CFL’s more energy-efficient consumption works to its advantage, eventually outweighing the environmental benefits of its competitor.

That advantage grows considerably due to the comparative lifespan of both bulbs: about 10,000 hours for a CFL, compared to around 1,000 hours for a standard incandescent.

Because actual use, rather than manufacturing or disposal, represents the largest proportion of a light bulb’s environmental impact, the source of electricity powering the lamp is an important factor. For example, an incandescent lamp run on electricity generated by a hydroelectric plant is less polluting than a CFL running on the standard European power mix.

“By choosing to power lamps with electricity generated in an environmentally friendly waym one can achieve more in ecological terms than by simply replacing incandescent bulbs with compact fluorescent lamps,” says Hischier.