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This isn't limited to cars either, but rather many "green" purchases in general. I remember one of my professors in an environmental studies course talking abou

This isn't limited to cars either, but rather many "green" purchases in general. I remember one of my professors in an environmental studies course talking about people replacing all the CFL bulbs in their home with LED ones when they came out, citing energy efficiency reasons. However, if you look at the manufacturing process of the LED bulbs and the disposal of the CFLs, the resulting environmental cost is greater than the power savings attributed to the LEDs (embodied energy/emissions). Obviously Marketing will downplay this impact as they want people to buy the new bulbs and feel good about helping the planet. The same goes for buying items made of recycled materials, a more power-efficient computer, and so forth. That's great - if you actually need the new item. If you are getting the replacement solely for environmental reasons you have to consider the impact of producing the new item and disposing of the old one before making that call.

yardie 5y ago
Most CFL bulbs for the home were total garbage. The colors were limited and the light was harsh. CFLs in the E26 bulb format ran too hot and the bulb electronic ballasts either smoked out or occasionally caught on fire. My country, France, banned incandescent bulbs early on. The CFL replacements were poor. The LED replacements that followed were significantly better.
robocat 5y ago
> LED bulbs and the disposal of the CFLs, the resulting environmental cost is greater than the power savings The CFD manufacture and disposal cost are sunken costs - you shouldn't include those in most calculations. Counter-intuitively for high use situations, the longer the CFD has left to live the more obvious it is to change it sooner to save $ and the environment. Assuming ① cost in dollars is proportional to environmental cost (edit: for both electricity and LED bulb), ② electricity costs $0.10 per kWh, ③ LED bulbs live as long as CFD bulbs, ④ LED bulb uses 7W whereas CFD uses 14W for the same lumen output, then if CFD has 5000 hours left, you can save $3.50 of electricity. If cost of LED is reasonably less than $3.50, it is obvious it makes sense to replace CFD with LED. If the bulb would never need to be replaced (examples: very low usage; you are moving out soon; or house is going to be demolished before bulb is replaced) then it may make sense to leave a CFD in place. The price of the LED is an investment with a payback period, so if you can't afford it or you have better returns for that investment elsewhere then you shouldn't replace the CFD. If your electricity comes from your own renewables, then the calculation is different again. Although note that in most countries nearly 100% of your reduced electricity usage will result in a nearly 100% reduction in non-renewables like gas or coal (even if your country is say 80% renewables). Marginal generation and usage matters. If you can find a better source than your professor, I would be interested.
- Spivak 5y ago
  > The CFD manufacture and disposal cost are sunken costs Yes but the manufacture and disposal of the LED aren't yet. The calculation you want is whether running the inefficient CFL ends up being better than the energy used in the whole supply chain of manufacturing and shipping the LED bulb. Switching means spending led_rate + 2 supply_chain costs while keeping your old bulbs means cfl_rate + 1 supply_chain. I'd put money that the latter being better for the environment. Edit: To the person who downvoted me but didn't reply do tell how literally throwing away a 10W CFL and replacing it with a 6W LED is better for the environment than just using the CFL until it breaks and then buying an LED.
  - robocat 5y ago
    When environmental savings due to using less electricity exceed the environmental cost of a new bulb, it is better to use a new bulb (with caveats). I carefully explained that literally. I didn't downvote you (can't downvote replies). I generally downvote people who comment about downvotes (even edits), since it is against HN guidelines. If you get downvotes, the value is in wondering to yourself: why. Not that the person who originally downvoted you is unlikely to reread your comment. I deserve downvotes for this comment for mentioning downvoting, and perhaps because I went off-topic. Edit: also IMHO worrying excessively about karma makes for unhealthy conversations.

yardie 5y ago

Most CFL bulbs for the home were total garbage. The colors were limited and the light was harsh. CFLs in the E26 bulb format ran too hot and the bulb electronic ballasts either smoked out or occasionally caught on fire. My country, France, banned incandescent bulbs early on. The CFL replacements were poor. The LED replacements that followed were significantly better.

robocat 5y ago

> LED bulbs and the disposal of the CFLs, the resulting environmental cost is greater than the power savings The CFD manufacture and disposal cost are sunken costs - you shouldn't include those in most calculations. Counter-intuitively for high use situations, the longer the CFD has left to live the more obvious it is to change it sooner to save $ and the environment. Assuming ① cost in dollars is proportional to environmental cost (edit: for both electricity and LED bulb), ② electricity costs $0.10 per kWh, ③ LED bulbs live as long as CFD bulbs, ④ LED bulb uses 7W whereas CFD uses 14W for the same lumen output, then if CFD has 5000 hours left, you can save $3.50 of electricity. If cost of LED is reasonably less than $3.50, it is obvious it makes sense to replace CFD with LED. If the bulb would never need to be replaced (examples: very low usage; you are moving out soon; or house is going to be demolished before bulb is replaced) then it may make sense to leave a CFD in place. The price of the LED is an investment with a payback period, so if you can't afford it or you have better returns for that investment elsewhere then you shouldn't replace the CFD. If your electricity comes from your own renewables, then the calculation is different again. Although note that in most countries nearly 100% of your reduced electricity usage will result in a nearly 100% reduction in non-renewables like gas or coal (even if your country is say 80% renewables). Marginal generation and usage matters. If you can find a better source than your professor, I would be interested.

Spivak 5y ago
> The CFD manufacture and disposal cost are sunken costs Yes but the manufacture and disposal of the LED aren't yet. The calculation you want is whether running the inefficient CFL ends up being better than the energy used in the whole supply chain of manufacturing and shipping the LED bulb. Switching means spending led_rate + 2 supply_chain costs while keeping your old bulbs means cfl_rate + 1 supply_chain. I'd put money that the latter being better for the environment. Edit: To the person who downvoted me but didn't reply do tell how literally throwing away a 10W CFL and replacing it with a 6W LED is better for the environment than just using the CFL until it breaks and then buying an LED.
- robocat 5y ago
  When environmental savings due to using less electricity exceed the environmental cost of a new bulb, it is better to use a new bulb (with caveats). I carefully explained that literally. I didn't downvote you (can't downvote replies). I generally downvote people who comment about downvotes (even edits), since it is against HN guidelines. If you get downvotes, the value is in wondering to yourself: why. Not that the person who originally downvoted you is unlikely to reread your comment. I deserve downvotes for this comment for mentioning downvoting, and perhaps because I went off-topic. Edit: also IMHO worrying excessively about karma makes for unhealthy conversations.