How much energy does it take to create a single light bulb?

Question

This question is a part of this question. Perhaps it is better suited on the physics SE, but here goes.

I would like to know how much energy it takes, in the modern world, to construct an ordinary, ready-to-buy light bulb, from the raw materials in the ground.

In the end, I would like to know it for the following types of bulbs:

1. Tungsten-filament
2. Halogen
3. Fluorescent tube
4. LED

For example, to create a tungsten-filament light bulb, you would need

• tungsten
• glass
• a few types of metal
• a few types of plastic
• a mixture of gases inside the bulb
• cardboard and plastics for the packaging
• etc.

These raw materials all require energy input:

• Forming/shaping

  • extracting tungsten from the ores, ..., creating filaments, ...
  • creating the right kind of glasses, ..., creating bulb housing, ...
  • etc.

• Transportation

  • of all the materials to their respective factories
  • of all the (half-)products to the bulb factory
  • of the bulb to the distribution centers/shop
  • etc.

• Losses

  • a small percentage of the raw materials will be rejected
  • a small percentage of the finished light bulbs will not work, and get rejected
  • energy expenditure of the robotic components and other tools in the involved factories

I realize this is virtually impossible to answer accurately for even a specific light bulb from a specific store, let alone make general statements -- there are simply too many steps in between to be able to trace everything "back to the ground".

What I'm looking for, is authorative sources on this subject. Studies done on the energy demands of modern production lines, hopefully, with this type of product in particular. I'd like to come to a more complete list than the one above, and some reasonable estimates on the energy expenditure in each step, ideally for each type of lightbulb.

Answer 1

The answer you are looking for would be contained in a Life Cycle Assessment (LCA). For an LCA you first want to determine the boundaries that are important to your question. Are you considering cradle to grave (disposal)? Cradle to cradle (recycling after use)? What are the boundaries for recycled source materials if used to make the light bulbs? The boundaries are a subjective choice, but you will want to be aware that different manufacturers may give you data with different boundaries and you will need to account for that when possible.

(Side note: energy is just one of many environmental performance indicators that may be included in an LCA.)

The different industries are in the process of developing Product Category Rules (PCR) which set guidelines for how to measure environmental impacts appropriate to their product. These rules are developed by consensus of industry experts in accordance with several ISO standards (14025, 14040-14043, 21930, etc.) and allow for fair comparisons between the products of different manufacturers. The PCRs are just being developed, so they can be hard to find. Here is an example for LED lighting.

After the PCR has been developed, manufacturers can produce Environmental Product Declarations (EPD) for their products, which are then verified by a third party (an organization like UL, appropriate to the product). The US Lifecycle Inventory Database is one organization that is trying to compile the EPDs from various manufacturers.

This is all a long way of saying that your question may be even more complex than you realize. There are lots of people working towards not just an answer, but a structure to give that answer relevant context. The terminology above will help you find that answer when it becomes available.

Answer 2

Some of the steps or inputs may be missing for light bulbs in particular, but in general the U.S. Life cycle Inventory Database (http://www.nrel.gov/lci/) has this sort of data.