Energy | 17. September 2010 | posted by Jan Oliver Löfken

Energy question of the week: How much energy can be saved by using the successors to incandescent light bulbs?

Gradually, the lights are going out over Europe; but this time, only the incandescent ones. Last year, the EU banned the sale of 100- and 75-watt bulbs, and 60-watt bulbs followed them a few weeks ago. By 2012, incandescent bulbs – which transform only five percent of their input power into light and the rest into heat – will no longer be on sale anywhere in Europe. But what will the result of this ban be?

The potential savings throughout the 27 states of the EU can be seen easily. Around 40 terawatt-hours – around one third of current energy consumption for lighting – can be saved every year and carbon dioxide emissions reduced by millions of tons. At the moment, the market is dominated by replacements based on fluorescent tube energy saving bulbs. With an efficiency of around 50 percent, these increase light output to around 80 lumens (the light energy output of a source) per watt in comparison to the maximum 20 lumens per watt of incandescent bulbs.

Warm white light from fluorescent tubes

In the early days, the 'cold' light of energy saving bulbs and the time it took for them to reach maximum output made them very unattractive to consumers. But these problems have largely been solved and they now emit a comfortable, 'warm white' light. They are still more expensive than incandescent bulbs, but this is paid back by their 12,000-hour life – around ten times longer than that of the old type.

The era of energy-saving bulbs, which usually contain the toxic heavy metal mercury, will not last much longer. Their competitors are already on the market. Light Emitting Diode (LED) bulbs with efficiencies of up to 90 percent will reduce power consumption further. Apart from an extremely long life of 50,000 hours, they also have the advantage that they can shine in the entire visible spectrum, provided the lamp contains several different LEDs. However, LED lamps will be used mainly in the workplace or in pocket torches, since they emit light from a point source and not over a wide angle. Their share of technical applications is growing fast, for instance in car headlights and traffic lights.

OLED-Lichtquelle: Organische LeuchtdiodenRevolutionary OLED lights

Completely new options for lighting the home are already on the horizon. These are organic LEDs, or OLEDs. In contrast to normal, semiconductor LEDs, they work by exciting plastic particles. These are distributed over a large surface area – potentially also flexible – so that shining wallpaper or curtains are no longer in the realm of science fiction. But it will be a few more years before OLEDs become available commercially; manufacturers still have to increase their output and especially their lifespan.

The DLR Energy question of the week in 'The future of energy' Year of Science

The Federal Ministry of Education and Research (BMBF) has given the Year of Science 2010 the motto 'The future of energy'. For this reason the science journalist Jan Oliver Löfken will this year answer a question on the subject of energy in his blog each week. Do you have a question about how our energy supply might look in the future? Or do you want to know, for example, how a wave power plant works and how it can efficiently generate electricity? Then send us your question by email. Science journalist Jan Oliver Löfken will investigate the answers and publish them each week in this blog.


Image credits: OSRAM Pressbild.


About the author

Energy journalist Jan Oliver Löfken writes among other things, for the Technologie Review, Wissenschaft aktuell, Tagesspiegel, Berliner Zeitung and P.M. Magazin on issues involving energy research and industry. For DLR, he answered the Energy question of the week during the Year of Energy 2010. to authorpage