Monday, June 25, 2007

How green are low energy bulbs?

The EU has ruled that ordinary 40W / 60W / 100W incandescent lamps will be banned from 2012. The decree is that domestic lights will be replaced with ‘energy saving’ lightbulbs (or, more correctly ‘compact fluorescent lamps’ or CFLs) in the interest of energy saving and reducing our carbon footprint. It is claimed that these CFLs use 25% of the energy and last eight times as long as the equivalent incandescent lamps – and so will help “save the planet”.

To understand more, some key things to know about are apparent power, real power and the power factor. Apparent power is the amount of energy an electricity company needs to supply to produce the real power required by a component or a piece of equipment. Electrical equipment where the apparent power is the same as the real power has a power factor of 1. If a piece of equipment requires more apparent power to produce the real power, it has a power factor of less than 1. It doesn’t take a genius to work out that equipment with a power factor nearer 0 is not as ‘green’ or ‘environmentally sensitive’ as an electrical component with a power factor nearer 1.

Knowing this, I’ve tested several CFLs with surprising results: taking a sample 60W light bulb as a reference against the equivalent 13W CFL, the CFL used more than twice as much apparent power as real power. Compared with ordinary incandescent light bulbs, CFLs have a poor power factor because they require more than the minimum apparent power to supply the real power.

My tests have shown that the CFLs use half the power of a 60W lamp, not quarter as stated and that’s before taking into account the extra power the supplier must generate.

The power difference between the real power consumed by the CFL (in the case of the Osram, it’s almost 15 watts) and the apparent power is wasted in more ways than one. The electricity supply becomes less efficient because it senses the difference between the real and apparent and becomes unbalanced by the redundant currents swilling around. The result is that it must generate more power than is really being used and the system needs to be upgraded to handle it. The cost of generation goes up and so the cost to the consumer goes up with it. The net result of using CFLs is that there is no saving whatever… quite the opposite; the electricity supply system has doubled its output and doubled its carbon emissions. The more people use CFLs, the worse the problem will become. And that’s before we’ve even talked about the fact that CFLs use mercury in their construction, which leads to more issues in their disposal. Utter stupidity… isn’t it better just to switch off a few lights?

What has all this got to do with your system? Hi-Fi and Home Cinema systems contain transformers and often have a low power factor. A 100W amplifier can demand up to 100 amps from the electricity supply for a millisecond to reproduce a drum transient. The lower the power factor, the less current is available to accurately reproduce the dynamics of your music – it’s effectively being used as ‘apparent’ power. And the more CFLs you fit, the worse the situation becomes. Me? I’m going back to candles!