Last May, I went to a summit of Northeast Energy Efficiency Partnerships (NEEP). It was not an academic conference, but I was interested in energy saving technologies, which are commercially available, and energy efficiency policies of local governments. There was exhibition, and the most popular item was LED bulb and floor light. Here are some pictures that I took:
You might notice that they all have large metal heat sink. I didn't know that LED emit strong heat. I asked an engineer friend at RPI, who is majoring in LED technology, and he told me that single LED emit ignorable heat, but when condensed for brightness, total heat cannot be ignored. Well, that's common sense. At an exhibition booth, I heard that their company was developing water-cooler for LED bulb, which could significantly reduce the bulb size but was not easy to make at that time. I have not heard whether they have succeeded in the development.
LED is much energy efficient. That's true. But one question that I wanted to ask is total energy use of LED in its life cycle. How much energy is needed in producing metal heat sink? Does anybody know about life cycle analysis of LED? If you let me know, I will appreciate. Energy efficiency is never easy to assess.