31:T422,// JSON.stringify( results_chart = embed( vl .data(total_emissions_data) .transform( vl .groupby(["Lifecycle Stage", "Vehicle Type"]) .aggregate(vl.sum('Tonnes CO2').as("Tonnes CO2")), vl .stack("Tonnes CO2") .groupby("Vehicle Type") .sort({ field: 'Lifecycle Stage', order: 'ascending' }), vl .calculate("(datum['Tonnes CO2_start'] + datum['Tonnes CO2_end'])/2") .as("sum_Tonnes CO2_mid") ) .layer( vl.markBar().encode( vl.x().fieldN("Vehicle Type"), vl .y() .fieldQ("Tonnes CO2_start") .axis({ title: 'Tonnes CO2' }), vl.y2().fieldQ("Tonnes CO2_end"), vl.color().fieldN("Lifecycle Stage") ), vl.markText({ dy: -0 }).encode( vl.x().fieldN("Vehicle Type"), vl.y().fieldQ("sum_Tonnes CO2_mid"), vl .text() .fieldN('Tonnes CO2') .format(',.1f') ) ) .width(200) .toSpec() ) // .toSpec(), // null, // null // )32:T50e,further_considerations = md`## Further considerations #### Substitution effects Selling an ICE vehicle increases the supply of second hand ICE cars, depressing their price. If vehicles get cheaper, it's plausible more miles may be driven in total. #### Positive externalities Purchasing electric vehicles is likely to result in the technology maturing more rapidly, decreasing the energy cost of production and increasing the relative desirability. By increasing demand for electricity and reducing demand for petrol/diesel, it may also accelerate the transition to cleaner electricity. #### Marginal vs average electric carbon intensity The mix of electricity generation in many countries includes a substantial percentage of renewables. In the short run, marginal electricity usage presumably comes from non-renewable energy sources, since short-term increases in demand are usually made up by non-renewable sources like natural gas. Arguably, the assumption you use for the carbon intensity of electricity production should be based on marginal rather than average production. In the UK, this would likely be gas-fired power stations, which is around [500gCO2/KWh](https://www.parliament.uk/globalassets/documents/post/postpn_383-carbon-footprint-electricity-generation.pdf). `33:T4d6,annex = md`## Annex - Source for assumptions: **Carbon intensity of electricity production**: - [DEFRA conversion factors](https://gist.github.com/RobinL/2d253d1b5a4a27e563fd1ce811c1bb86#file-defra_conversion_factors_2019-csv-L1928). For other countries [see page 74](https://ec.europa.eu/clima/sites/default/files/transport/vehicles/docs/2020_study_main_report_en.pdf). For comparison of different sources of electricity, see [here](https://www.parliament.uk/globalassets/documents/post/postpn_383-carbon-footprint-electricity-generation.pdf). **Emissions from production of electric vs ICE vehicles** - [Figure A11 Page 189 and Figure 12 page 191](https://ec.europa.eu/clima/sites/default/files/transport/vehicles/docs/2020_study_main_report_en.pdf) for carbon emissions from production of ICE/electric - Or alternatively you can derive a figure of around 9 tonnes for ICE and 14 tonnes for electric from [figure ES5 on page 9](https://ec.europa.eu/clima/sites/default/files/transport/vehicles/docs/2020_study_main_report_en.pdf). **Uplift in ICE emissions from production fuel cycle** - Derived from [figure ES5 on page 9](https://ec.europa.eu/clima/sites/default/files/transport/vehicles/docs/2020_study_main_report_en.pdf). `34:[] 2f:{"title":"How does switching to an electric car affect your carbon footprint?","cells":[{"id":0,"value":"title = md`# How does switching to an electric car affect your carbon footprint?`","pinned":false,"hidden":false,"mode":"ojs"},{"id":9,"value":"para_1 = md`This post considers three questions:\n\n- What is the total carbon footprint of an full electric vehicle versus an ICE (petrol/diesel) equivalent? \n\n- If you own an ICE car, is it better immediately to replace it with an full electric car, or wait until it is beyond economic repair.\n\n- Since electric cars are more expensive, may it be better for the environment to buy an ICE vehicle and use the balance to buy carbon offsets?\n\nThe answers to these questions depend on how you use your car, and other factors such as the mix of energy generation used to power the electric vehicle. Estimates for some important variables such as emissions from the production of vehicles are often imprecise, and vary considerably between sources. \n\nThis article provides default values which you may change. Sources for these default values are provided in the appendix.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":20,"value":"title_assumptions = md`## Assumptions`","pinned":false,"hidden":false,"mode":"ojs"},{"id":31,"value":"ice_mileage_md = md`Total expected lifetime mileage of ICE vehicle: ${inputs.bind(\n html``,\n viewof ice_lifetime_distance\n)} thousand ${inputs.bind(\n html`${km_miles_unit_select}`,\n viewof ice_lifetime_distance_units\n)}\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":117,"value":"elec_mileage_md = md`Total expected lifetime mileage of electric vehicle: ${inputs.bind(\n html``,\n viewof elec_lifetime_distance\n)} thousand ${inputs.bind(\n html`${km_miles_unit_select}`,\n viewof elec_lifetime_distance_units\n)}\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":141,"value":"total_emissions_ice_md = md`Total emissions in tonnes for ICE vehicle manufacture: ${inputs.bind(\n html``,\n viewof ice_production_emissions_tonnes\n)} tonnes (CO2 equivalent)`","pinned":false,"hidden":false,"mode":"ojs"},{"id":152,"value":"total_emissions_elec_md = md`Total emissions in tonnes for electric vehicle manufacture: ${inputs.bind(\n html``,\n viewof elec_production_emissions_tonnes\n)} tonnes (CO2 equivalent)`","pinned":false,"hidden":false,"mode":"ojs"},{"id":157,"value":"ice_vehicle_emissions_md = md`ICE vehicle emissions: ${inputs.bind(\n html``,\n viewof ice_emissions\n)} \n${inputs.bind(html`${ice_emissions_unit_select}`, viewof ice_emissions_unit)}`","pinned":false,"hidden":false,"mode":"ojs"},{"id":381,"value":"uplift_md = md`ICE uplift for fuel production cycle (energy required for extraction, production and transport of petrol/diesel): ${inputs.bind(\n html``,\n viewof ice_emissions_uplift_percent\n)} %`","pinned":false,"hidden":false,"mode":"ojs"},{"id":200,"value":"elec_miles_kwh_md = md`Electric vehicle energy usage: ${inputs.bind(\n html``,\n viewof elec_emissions\n)} \n${inputs.bind(html`${elec_emissions_unit_select}`, viewof elec_emissions_unit)}`","pinned":false,"hidden":false,"mode":"ojs"},{"id":205,"value":"carbon_intensity_md = md`Carbon intensity of electricity production: ${inputs.bind(\n html``,\n viewof elec_carbon_intensity\n)} gCO2/kWh`","pinned":false,"hidden":false,"mode":"ojs"},{"id":295,"value":"results_title = md`## Results\n\n### Total carbon emissions\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":583,"value":"results_para_1 = md`Total lifetime carbon emissions are ${total_ice_emissions.toPrecision(\n 3\n)} tonnes CO2 for the ICE car, and ${total_elec_emissions.toPrecision(\n 3\n)} tonnes CO2 for the electric car.\n\nThis makes lifetime electric emissions ${(\n (100 * total_elec_emissions) /\n total_ice_emissions\n).toPrecision(3)}% of ICE emissions.\n\nThe ICE vehicle will therefore have additional emissions of ${additional_emissions_ice.toPrecision(\n 3\n)} tonnes of CO2.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":410,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":905,"value":"results_table = md`\n| | ICE | Electric |\n|-----------------------|-----|----------|\n| Marginal emissions/km | ${marginal_ice_emissions_gCO2km.toFixed(\n 1\n)} gCO2/km | ${marginal_elec_emissions_gCO2km.toFixed(1)} gCO2/km |\n| Average emissions/km | ${average_ice_emissions_gCO2km.toFixed(\n 1\n)} gCO2/km | ${average_elec_emissions_gCO2km.toFixed(1)} gCO2/km |\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":656,"value":"results_carbon_offset = md`\n\n\n#### Carbon offsetting the difference \n\nCarbon offsetting costs vary wildly, between about [£6 and £300 per tonne](https://www.robinlinacre.com/offsetting_renewables/) - see also [here](https://www.gov.uk/flood-and-coastal-erosion-risk-management-research-reports/achieving-net-zero-carbon-emissions-a-review-of-the-evidence-behind-carbon-offsetting). The Greater London Authority uses a [carbon offset price of £60/tonne CO2](https://www.london.gov.uk/sites/default/files/carbon_offsett_funds_guidance_2018.pdf). \n\nUsing the £60 figure, the cost of offsetting the additional lifetime emissions from the ICE would be £${(\n additional_emissions_ice * 60\n).toFixed(2)}.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":618,"value":"replace_para_1 = md`### Replacing an ICE with an electric vehicle\nIf you own an existing ICE, is it better immediately to replace it with an electric vehicle or wait until it reaches the end of its life?\n\nThe production emissions of the ICE car are a sunk cost. This makes the relevant comparison the [marginal](https://www.investopedia.com/terms/m/marginal-analysis.asp#:~:text=that%20same%20activity.-,Marginal%20refers%20to%20the%20focus%20on%20the%20cost%20or%20benefit,them%20maximize%20their%20potential%20profits.) emissions of the ICE car (${marginal_ice_emissions_gCO2km.toFixed(\n 1\n)} gCO2/km) vs. the average emissions of the electric car (${average_elec_emissions_gCO2km.toFixed(\n 1\n)} gCO2/km). \n\nIf the former are higher than the later, then further use of the ICE results in higher overall emissions.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":645,"value":"replace_para_2 = md`Although switching immediately to an electric car usually reduces your overall emissions, it's important to recognise that the savings are relatively modest.\n\nSuppose that instead of immediately switching, suppose you keep your ICE for a further ${inputs.bind(\n html``,\n viewof ice_distance_remaining\n)} thousand ${inputs.bind(\n html`${km_miles_unit_select}`,\n viewof ice_distance_remaining_units\n)}.\n\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":680,"value":"replace_para_3 = md`The total carbon saving of immediately switching would be ${ice_emissions_for_marginal_useage.toPrecision(\n 3\n)} tonnes CO2.\n\nUsing the £60 per tonne of CO2 offsetting figure mentioned earlier, the cost would be £${(\n ice_emissions_for_marginal_useage * 60\n).toLocaleString('US-en', { maximumFractionDigits: 0 })}.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":759,"value":"breakeven_electric = md`## 'Break even' point for electric cars \n\nGiven that electric cars have greater carbon emissions from their production, how many miles must be driven before their total emissions fall below those of ICE vehicles?\n\nAs shown in the following chart, the breakeven distance is ${break_even_distance.toLocaleString(\n 'en-US',\n {\n maximumFractionDigits: 0\n }\n)} km.\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":774,"value":"breakeven_electric_chart = {\n let lines = vl\n .markLine()\n .data(break_even_data)\n\n .encode(\n vl\n .x()\n .fieldQ('Distance (km)')\n .axis({ title: 'Distance (km)' }),\n vl\n .y()\n .fieldQ('Tonnes CO2')\n .axis({ title: 'Tonnes CO2' }),\n vl.color().fieldN('Vehicle Type')\n )\n .title('Break even distance')\n .width(width - 200);\n\n return embed(vl.layer(lines, markrule_be, text_be).toSpec());\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":26,"value":"$32","pinned":false,"hidden":false,"mode":"ojs"},{"id":228,"value":"$33","pinned":false,"hidden":false,"mode":"ojs"},{"id":898,"value":"md`### Breakeven calcs`","pinned":false,"hidden":false,"mode":"ojs"},{"id":785,"value":"break_even_distance = {\n // y = a + m1 x\n\n // y = b + m2 x\n //x = (a-b)/(m1-m2)\n let a_b =\n 1e6 * (elec_production_emissions_tonnes - ice_production_emissions_tonnes);\n\n let m1_m2 = marginal_ice_emissions_gCO2km - marginal_elec_emissions_gCO2km;\n return a_b / m1_m2;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":766,"value":"break_even_data = {\n let rows = [];\n let p;\n p = { id: 0, \"Distance (km)\": 0, \"Tonnes CO2\": 0, \"Vehicle Type\": \"ICE\" };\n rows.push(p);\n\n p = {\n id: 1,\n \"Distance (km)\": 0,\n \"Tonnes CO2\": ice_production_emissions_tonnes,\n \"Vehicle Type\": \"ICE\"\n };\n rows.push(p);\n\n p = {\n id: 2,\n \"Distance (km)\": total_ice_km,\n \"Tonnes CO2\": ice_production_emissions_tonnes + ice_emissions_from_use,\n \"Vehicle Type\": \"ICE\"\n };\n rows.push(p);\n\n p = {\n id: 0,\n \"Distance (km)\": 0,\n \"Tonnes CO2\": 0,\n \"Vehicle Type\": \"Electric\"\n };\n rows.push(p);\n\n p = {\n id: 1,\n \"Distance (km)\": 0,\n \"Tonnes CO2\": elec_production_emissions_tonnes,\n \"Vehicle Type\": \"Electric\"\n };\n rows.push(p);\n\n p = {\n id: 2,\n \"Distance (km)\": total_ice_km,\n \"Tonnes CO2\": elec_production_emissions_tonnes + elec_emissions_from_use,\n \"Vehicle Type\": \"Electric\"\n };\n rows.push(p);\n\n return rows;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":858,"value":"text_be = vl\n .markText({ angle: -90, xOffset: -10, yOffset: -20 })\n .data({\n values: [\n {\n be_text: break_even_distance,\n y_pos: total_ice_emissions / 2,\n mytext:\n break_even_distance.toLocaleString('en-US', {\n maximumFractionDigits: 0\n }) + \" km\"\n }\n ]\n })\n .encode(vl.x().fieldQ('be_text'))\n .encode(vl.y().fieldQ('y_pos'))\n .encode(vl.text().fieldN('mytext'))","pinned":false,"hidden":false,"mode":"ojs"},{"id":801,"value":"markrule_be = vl\n .markRule({ color: 'red', size: 1, strokeDash: ['4', '4'] })\n .data({ values: [{ rule: break_even_distance }] })\n .encode(vl.x().fieldQ('rule'))","pinned":false,"hidden":false,"mode":"ojs"},{"id":396,"value":"md`## Chart data`","pinned":false,"hidden":false,"mode":"ojs"},{"id":398,"value":"total_emissions_data = {\n let rows = [];\n let r = {\n 'Lifecycle Stage': 'Production',\n 'Vehicle Type': 'Electric',\n 'Tonnes CO2': elec_production_emissions_tonnes\n };\n rows.push(r);\n\n r = {\n 'Lifecycle Stage': 'Use',\n 'Vehicle Type': 'Electric',\n 'Tonnes CO2': elec_emissions_from_use\n };\n rows.push(r);\n\n r = {\n 'Lifecycle Stage': 'Use',\n 'Vehicle Type': 'ICE',\n 'Tonnes CO2': ice_emissions_from_use\n };\n rows.push(r);\n\n r = {\n 'Lifecycle Stage': 'Production',\n 'Vehicle Type': 'ICE',\n 'Tonnes CO2': ice_production_emissions_tonnes\n };\n rows.push(r);\n\n return rows;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":406,"value":"md`## Chart specs`","pinned":false,"hidden":false,"mode":"ojs"},{"id":477,"value":"chart = vl\n .data(total_emissions_data)\n\n .layer(\n vl\n .markBar()\n .encode(vl.x().fieldN(\"Vehicle Type\"), vl.y().fieldQ(\"Tonnes CO2\"))\n )\n .width(100)\n .toSpec()","pinned":false,"hidden":false,"mode":"ojs"},{"id":224,"value":"md`## Conversions`","pinned":false,"hidden":false,"mode":"ojs"},{"id":226,"value":"total_ice_km = per(`kilometers/${ice_lifetime_distance_units}`) *\n ice_lifetime_distance *\n 1000","pinned":false,"hidden":false,"mode":"ojs"},{"id":258,"value":"total_elec_km = per(`kilometers/${elec_lifetime_distance_units}`) *\n elec_lifetime_distance *\n 1000","pinned":false,"hidden":false,"mode":"ojs"},{"id":262,"value":"marginal_ice_emissions_gCO2km = {\n let direct_vehicle_emissions_gCO2km;\n if (ice_emissions_unit == \"mpg\") {\n let kg_per_gallon = per(\"kg_co2_from_petrol/imperial_gallons_petrol\");\n let kg_per_mile = kg_per_gallon / ice_emissions;\n let kg_per_km = kg_per_mile * per(\"miles/kilometers\");\n\n direct_vehicle_emissions_gCO2km = kg_per_km * 1000;\n }\n\n if (ice_emissions_unit == \"gCO2km\") {\n direct_vehicle_emissions_gCO2km = ice_emissions;\n }\n\n return (\n direct_vehicle_emissions_gCO2km * (1 + ice_emissions_uplift_percent / 100)\n );\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":304,"value":"marginal_elec_emissions_gCO2km = {\n let distance_units;\n if (elec_emissions_unit == \"miles_per_kWh\") {\n distance_units = \"miles\";\n }\n if (elec_emissions_unit == \"km_per_kWh\") {\n distance_units = \"kilometers\";\n }\n let conversion_factor = per(`kilometers/${distance_units}`);\n let kwh_per_km = elec_emissions * conversion_factor;\n let elec_emissions_gCO2km = elec_carbon_intensity / kwh_per_km;\n return elec_emissions_gCO2km;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":353,"value":"ice_emissions_from_use = (marginal_ice_emissions_gCO2km * total_ice_km) / 1e6","pinned":false,"hidden":false,"mode":"ojs"},{"id":357,"value":"elec_emissions_from_use = (marginal_elec_emissions_gCO2km * total_elec_km) / 1e6","pinned":false,"hidden":false,"mode":"ojs"},{"id":311,"value":"total_ice_emissions = ice_emissions_from_use + ice_production_emissions_tonnes","pinned":false,"hidden":false,"mode":"ojs"},{"id":367,"value":"total_elec_emissions = elec_emissions_from_use +\n elec_production_emissions_tonnes","pinned":false,"hidden":false,"mode":"ojs"},{"id":641,"value":"average_elec_emissions_gCO2km = (total_elec_emissions / total_elec_km) * 1e6","pinned":false,"hidden":false,"mode":"ojs"},{"id":913,"value":"average_ice_emissions_gCO2km = (total_ice_emissions / total_ice_km) * 1e6","pinned":true,"hidden":false,"mode":"ojs"},{"id":690,"value":"ice_distance_remaining_km = per(`kilometers/${ice_distance_remaining_units}`) *\n ice_distance_remaining *\n 1000","pinned":false,"hidden":false,"mode":"ojs"},{"id":696,"value":"ice_remaining_emissions = (ice_distance_remaining_km *\n marginal_ice_emissions_gCO2km) /\n 1e6","pinned":true,"hidden":false,"mode":"ojs"},{"id":1011,"value":"elec_remaining_emissions_equivalent = (ice_distance_remaining_km *\n average_elec_emissions_gCO2km) /\n 1e6","pinned":false,"hidden":false,"mode":"ojs"},{"id":1009,"value":"ice_emissions_for_marginal_useage = ice_remaining_emissions -\n elec_remaining_emissions_equivalent","pinned":false,"hidden":false,"mode":"ojs"},{"id":716,"value":"additional_emissions_ice = total_ice_emissions - total_elec_emissions","pinned":true,"hidden":false,"mode":"ojs"},{"id":213,"value":"md`## Inputs/views`","pinned":false,"hidden":false,"mode":"ojs"},{"id":40,"value":"viewof ice_lifetime_distance = new inputs.input(100)","pinned":false,"hidden":false,"mode":"ojs"},{"id":125,"value":"viewof elec_lifetime_distance = new inputs.input(100)","pinned":false,"hidden":false,"mode":"ojs"},{"id":75,"value":"viewof ice_lifetime_distance_units = new inputs.input(\"miles\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":121,"value":"viewof elec_lifetime_distance_units = new inputs.input(\"miles\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":147,"value":"viewof ice_production_emissions_tonnes = new inputs.input(9)","pinned":false,"hidden":false,"mode":"ojs"},{"id":154,"value":"viewof elec_production_emissions_tonnes = new inputs.input(14)","pinned":false,"hidden":false,"mode":"ojs"},{"id":165,"value":"viewof elec_emissions_units = new inputs.input(\"gCO2km\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":173,"value":"viewof ice_emissions = new inputs.input(\"40\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":185,"value":"viewof ice_emissions_unit = new inputs.input(\"mpg\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":388,"value":"viewof ice_emissions_uplift_percent = new inputs.input(\"50\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":174,"value":"viewof elec_emissions = new inputs.input(\"4\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":190,"value":"viewof elec_emissions_unit = new inputs.input(\"miles_per_kWh\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":210,"value":"viewof elec_carbon_intensity = new inputs.input(\"250\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":666,"value":"viewof ice_distance_remaining = new inputs.input(\"30\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":670,"value":"viewof ice_distance_remaining_units = new inputs.input(\"miles\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":78,"value":"km_miles_unit_select = ``","pinned":false,"hidden":false,"mode":"ojs"},{"id":193,"value":"elec_emissions_unit_select = ``","pinned":false,"hidden":false,"mode":"ojs"},{"id":159,"value":"ice_emissions_unit_select = ``","pinned":false,"hidden":false,"mode":"ojs"},{"id":216,"value":"md`## Imports`","pinned":false,"hidden":false,"mode":"ojs"},{"id":87,"value":"inputs = require(\"@observablehq/inputs\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":243,"value":"eu = require(\"@robinl/energy_usage@0.1.6\")","pinned":true,"hidden":false,"mode":"ojs"},{"id":245,"value":"per = eu.convert.per","pinned":true,"hidden":false,"mode":"ojs"},{"id":408,"value":"import { vl } from \"@vega/vega-lite-api\"","pinned":true,"hidden":false,"mode":"ojs"},{"id":637,"value":"embed = require(\"vega-embed@6\")","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W34","stdlib":"1","titling":"auto"}