Improved calculation

examples/country.rs

@@ -6,8 +6,8 @@ use num_format::{Locale, ToFormattedString};
 use simple_logger::SimpleLogger;
 
 use flights::{
-    emissions, leg_co2_kg, load_aircraft_consumption, load_aircrafts, load_private_jet_types,
-    AircraftTypeConsumptions, Class, Fact, Leg, Position,
+    emissions, leg_co2_kg, leg_co2_kg_per_person, load_aircraft_consumption, load_aircrafts,
+    load_private_jet_types, AircraftTypeConsumptions, Class, Fact, Leg, Position,
 };
 use time::Date;
 
@@ -393,7 +393,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
         private_emissions(&legs, &consumptions, |leg| leg.distance() < 300.0);
     let commercial_emissions_short = commercial_emissions(&legs, |leg| leg.distance() < 300.0);
 
-    let short_ratio = emissions_short_legs / commercial_emissions_short;
+    let short_ratio = leg_co2_kg_per_person(emissions_short_legs) / commercial_emissions_short;
     let ratio_train_300km = Fact {
         claim: (short_ratio + 7.0) as usize,
         source: format!("{}x in comparison to a commercial flight[^1][^6] plus 7x of a commercial flight in comparison to a train, as per https://ourworldindata.org/travel-carbon-footprint (UK data, vary by country) - retrieved on 2024-01-20", short_ratio as usize),
@@ -406,7 +406,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
     let commercial_emissions_long = commercial_emissions(&legs, |leg| leg.distance() >= 300.0);
 
     let ratio_commercial_300km = Fact {
-        claim: (emissions_long_legs / commercial_emissions_long) as usize,
+        claim: (leg_co2_kg_per_person(emissions_long_legs) / commercial_emissions_long) as usize,
         source: "Commercial flight emissions based on [myclimate.org](https://www.myclimate.org/en/information/about-myclimate/downloads/flight-emission-calculator/) - retrieved on 2023-10-19".to_string(),
         date: now.to_string(),
     };

methodology.md

@@ -102,7 +102,6 @@ leg emissions [kg CO2e] =
   x Radiative Forcing index [kg CO2e / kg CO2]
   x Life-cycle emissions [kg CO2e / kg CO2e]
   x leg time [h]
-  x occupancy [1/person]
 ```
 
 Where:
@@ -114,6 +113,17 @@ Where:
 * `Radiative Forcing index = 3 [kg CO2e / kg CO2]`, as concluded in [The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018](https://www.sciencedirect.com/science/article/pii/S1352231020305689), from 2021.
 * `Life-cycle emissions = 1.68 [kg CO2e / kg CO2e]`, [Life Cycle Greenhouse Gas Emissions from Alternative Jet Fuels v1.2](https://web.mit.edu/aeroastro/partner/reports/proj28/partner-proj28-2010-001.pdf) from 2010-06, accessed 2024-01-28.
 * `leg time [h]` is obtained by computing duration of the leg, as identified via the methodology `M-4` in this document.
+
+#### Per passager
+
+```
+leg emissions/person [kg CO2e/person] =
+  leg emissions [kg CO2e]
+  x occupancy [1/person]
+```
+
+where
+* `leg emissions [kg CO2e]` is as computed above
 * `occupancy = 0.23 [1/person] = 1/4.3 [1/person]` obtained from [Average number of passengers per flight who flew private worldwide from 2016 to 2019](https://www.statista.com/statistics/1171518/private-jet-per-flight/), where there were 4.3 passagers per flight in 2019, accessed 2024-01-28.
 
 ### M-8: Identify aircraft owner in Denmark

src/lib.rs

@@ -28,7 +28,7 @@ pub use icao_to_trace::*;
 pub use legs::*;
 pub use model::*;
 pub use owners::*;
-pub use private_emissions::leg_co2_kg;
+pub use private_emissions::*;
 
 /// A position of an aircraft
 #[derive(Debug, Clone, PartialEq, serde::Serialize, serde::Deserialize)]

src/private_emissions.rs

@@ -17,5 +17,11 @@ pub fn leg_co2_kg(consumption: f64, duration: time::Duration) -> f64 {
         * EMISSIONS_PER_KG
         * RADIATIVE_INDEX
         * LIFE_CYCLE_FACTOR
-        * OCCUPANCY_FACTOR
+}
+
+/// Returns the total CO2 emissions per person in kg of a private jet with a given
+/// consumption (in GPH) of Jet-A fuel flying for a given amount of time,
+/// as specified in [methodology `M-7`](../methodology.md).
+pub fn leg_co2_kg_per_person(emissions: f64) -> f64 {
+    emissions * OCCUPANCY_FACTOR
 }