Everyday equivalents of a quantity of CO2-equivalent

Converts grams of CO2-equivalent into two everyday comparisons: kilometres driven in an average European passenger car (175 gCO2/km) and tree-months of carbon sequestration (917 gCO2 per tree per month), the two comparisons the Green Algorithms calculator prints, with their sources. Use it to make the co2eg of co2fp easier to read in a report.

Usage

fpeqv(co2eg)

Arguments

co2eg: Numeric scalar, grams of CO2-equivalent; finite and non-negative (for example the co2eg element of a co2fp result).

Value

A list with carkm (numeric, kilometres), treemon (numeric) and sources (named character vector, car and tree, naming each factor's source).

Details

The conversions are plain divisions: \(\mathrm{km} = g / 175\) and \(\mathrm{tree\ months} = g / 917\). Both factors are averages and the comparisons are illustrations, not offsets: a tree-month is the carbon one mature tree takes up in a month, not a promise that planting one cancels the emission. Errors when co2eg is not a single finite, non-negative number.

References

Green Algorithms data v3.1, context.csv: car factor from Helmers et al. (2019) Atmospheric Environment and UK BEIS 2019 conversion factors; tree sequestration from Bernal et al. (2018) via the same file.

Examples

fpeqv(1200)
#> ╭── Footprint in everyday terms ────────────────────────────────────────╮
#> │   Car travel   6.857 km                                               │
#> │   Tree uptake  1.309 tree-months                                      │
#> │                                                                       │
#> │   The same emissions as driving a European passenger car this far, or │
#> │   what this many trees take up in a month.                            │
#> │                                                                       │
#> │   car: 175 gCO2/km, European passenger car (Green Algorithms          │
#> │   context.csv). tree: 917 gCO2 per tree-month (Green Algorithms       │
#> │   context.csv).                                                       │
#> ╰───────────────────────────────────────────────────────────────────────╯

# the footprint of a small computation, in everyday terms
fp <- co2fp(sum(sqrt(seq_len(2e5))), loc = "CA-ON",
                        cpupwrw = 45, memgb = 8)
unlist(fpeqv(fp$co2eg)[c("carkm", "treemon")])
#>        carkm      treemon 
#> 4.109534e-09 7.842621e-10 

# a vector is refused: convert one total at a time
try(fpeqv(c(10, 20)))
#> Error : `co2eg` must be a single non-negative number