search

thangdnsf / consumsis

consumption analysis plugin for chrome browser
1 stars 0 forks source link

Issues in conversion factors #2

Open ggael opened 4 years ago

ggael commented 4 years ago

The conversion factor for walking is currently set as 750gCO2e/km:

const co2perwalkingkm = 0.75;

which is three times the factor by car !

Pessimistic estimations are closer to 0.01, but converting a walking distance to CO2e is really tricky and subject to endless debates on what should be taken into account. I would thus strongly advice to remove this metaphor.

The same remark applies for bicycling.

For electricity, 0.035 kgCO2e/kWh in France is extremely optimistic (it seems to come from the IEA) and this number neglects the importations and infrastructures. A more consensual value would be 0.056 as reported by the ADEME, or independently computed by electricy map. Others report 0.086 or even 0.112.

thangdnsf commented 4 years ago

We got this measurement according to the bellow paper and we also surprised by this. We will consider this problem and try to find other alternative metaphors. The sums were done by Chris Goodall, campaigning author of How to Live a Low-Carbon Life, based on the greenhouse gases created by intensive beef production. “Driving a typical UK car for 3 miles [4.8km] adds about 0.9 kg [2lb] of CO2 to the atmosphere,” he said, a calculation based on the Government’s official fuel emission figures. “If you walked instead, it would use about 180 calories. You’d need about 100g of beef to replace those calories, resulting in 3.6kg of emissions, or four times as much as driving. http://www.climatechangechallenge.org/News/Featured-Articles/Walking_to_the_shops_damages_planet_more_than_going_by_car.htm

ggael commented 4 years ago

This old article has been debunked many times. Firstly, it assumes that you'll have to eat more to compensate a short walk, which is debatable. Secondly, and more importantly, it assumes that you're taking the additional kcal exclusively from meet. But meet is a poor source of kcal because it has zero carbohydrate, and the production of meet is extremely bad in terms of GHG emissions. So provided that you'll have to eat more to compensate, you're going to need carbohydrates as in rice, potatoes, pasta, etc. So now let's do some computation. For 1 km of walk at 5km/h you'll need about 40kcal from which you should remove the amount of kcal you would consume anyway just not to die (about 100kcal/h for sitting in front of your computer). This yields 20kcal. Using numbers from Pimentel et al. [2008] we get about: