# WTW versus LCA approach in carbon footprint calculations?

I recently did some carbon footprint calculations for the organization I work for. I used conversion factors I found at the Dutch CO2 emission factors website. This website lists standard emission factors for various energy sources to make it easier to calculate one's carbon footprint and so people can more easily compare carbon footprint reports.

On the site they say that for electricity generated by Dutch wind, solar or hydro-power plants you should use 0 kg/CO2. The site also remarks that this is the Well-To-Wheel (WTW) approach (a.k.a. in-use approach) and that for a Life-Cycle Analysis (LCA) approach you can use 12 grams CO2/kWH for wind, 4 grams/kWh for hydro and 70 grams/kWh for solar.

The LCA looks much more accurate to me, but all Dutch carbon footprint reports I read use the WTW approach. How come this is the standard approach here in the Netherlands? And how is this in other countries? Why would people want to use a less accurate WTW approach (other than making their impact look less bad)?

• Another way of looking at it is that WTW is the marginal (carbon) cost, while LCA attempts an estimate of the manufacturing cost divided by the lifetime output. That's a few extra variables to assess Nov 27, 2019 at 8:54
• @ChrisH I guess you are saying it's more work. That could be a reason. In my case the numbers are already given for electricity from renewable sources, but I would also need to take manufacturing and disposal into account for other components in my calculations. Nov 27, 2019 at 9:21
• Not so much more work (though it is), as more margin for error and subtle forms of bias. Those values further depend on externals - e.g. if your wind turbines have to sit idle for significant periods because their power can't be used due to grid capability limits, but still only last the same number of years, your LCA value changes, but your WTW value doesn't. Nov 27, 2019 at 10:05
• This only really looks at the underlying reasons behind the existence of two valid approaches; when and why each should be used is much more political. Consistency is important, and using LCA figures for the tech you don't like but WTW for the one you do is a common trick used by proponents of both electric vehicles and traditional cars. Nov 27, 2019 at 10:08