GHG emissions for the average American

Transcription

1 GHG emissions for the average American Joe Bloggs November 5, Background For the purposes of figuring out how to cut our GHG emissions, it is instructive to first sort out where they come from. So, we will break down the energy-consuming activities of everyone of us, try to figure out what is average, and then from there estimate the emissions. We will go with the things that we all do: eating, living and sleeping in a house, getting around, working. There are also things that we do as a society, that benefit us individually and consume energy. We will try to estimate that bit too. 1.1 Eating Figure 1: average caloric intake of average american diet Fig. 2 (from USDA) shows the calories we eat daily on average. The website Earth Sciences Stack Exchange gives the following table: So, from the data in Figs. 2 and 2, we can calculate the numbers we seek: 1

2 Figure 2: kg of CO2 emitted per 1000 calories of food product Fruits and vegetables We average all the fruits and vegetables on the table, giving 2.49 kg / 1000 calories, so 206 calories of fruit & veg produces kg of CO Grain products The only grain product in the table is rice, so we co with that. This produces = 1.27 kg of CO Fats and oils Well, the table does not have a category for any of this. Since cheese is mostly fat, we will use that instead, at 4.47 kg CO2 per 1000 calories. For the 590 calories of this category, we get 2.64 kg of CO Meat, eggs and nuts For this category, we get an average of 6.90 kg CO2 per 1000 calories, by including lamb, beef, turkey, tuna, salmon, pork, chicken, eggs and nuts. Total CO2 emissions for this category are 3.76 kg of CO2. 2

3 1.1.5 Caloric sweeteners Well, the table does not have data for this. So, since potatoes are starch and similar to sugar, we go with that value, 1.46 kg CO2 per 1000 calories. This gives us 0.58 kg of CO Dairy Since we counted cheese in the fats, we just use the value for milk in this category to not double count. At 3.17 kg CO2 per 1000 calories, our milk consumption produces 0.69 kg of CO2 per day Summary for food In total, we produce 9.45 kg CO2 per day, equivalent to 3.45 tons per year. 1.2 House The average house, per the class notes, is 2,687 sq.ft. in surface area. The national association of home builders published an interesting graphic on energy use in homes (Fig. 3). Figure 3: Daily energy use per unit area for US homes. 3

4 We make the following assumptions for the calculations: 33.3% of HVAC is electric AC, 66.7% of HVAC is gas heating, and the rest of the consumption is electricity AC HVAC energy consumption is, on average, 41.8 Btu per sq.ft. per day. So for the average house we have kwh of electricity per day for AC. At kg CO2 per kwh, this corresponds to 6.47 kg of CO2 per day Gas heating For gas heating, the daily BTU amount is 224,633 BTU. This corresponds (assuming natural gas) to 26.3 lb. or kg of CO2 per day Electricity The rest (77.47 BTU per day per sq.ft., or 61 kwh per day) is electricity. Again, at kg CO2 per kwh, we have 36.1 kg of CO2 per day Summary for housing The average house releases 54.5 kg CO2 per day, or tons per year. 1.3 Getting around OK so here we consider two main modes of transportation that average americans use often: cars and planes. So for cars, the average number of miles driven is 13,474. In 2017 the fuel economy of new cars and trucks hit a record of 24.7 mpg. Given that the average car is 11.6 years, we will use the average fuel economy for 2007 instead, of 21 mpg from Washington Post report. Also the average number of passengers in a car is 1.67, so we divide by that number to get total gallons used. This comes out to 384 gallons of gasoline per person. At 9.07 kg of CO2 per gallion of gasoline, this means 3.84 tons of CO2 per year for driving. The average person in the US takes 2.1 trips per year (from class notes). Since the average flight is 1166 miles per haul, assuming 2.1 return trips, this gives 4897 miles per year. The average fuel efficiency per passenger mile for us air carriers is mpg GGE (gallon of gasoline equivalent, from Oak Ridge Lab report), this means 96 gallons of gasoline, equivalent to 0.87 tons of CO2 per year. So, the total CO2 emissions for getting around are 4.71 tons. 4

5 1.4 Work The total number of working people in the US are 126 million. If we assume that all of these people work in a commercial building of some kind (ok, some people may work out in the fields or in the coal mines, but that is definitely a minority) then we can figure out how much energy per capita is required for our workplace. The total electricity consumption of commercial buildings in the US is, according to Energy Information Administration, was 1,243 billion kwh. This constituted 61% of the total energy end-use, so the non-electricity use is 795 billion kwh. Per worker, this corresponds to 9,865 kwh of electricity and 6,307 kwh of non-electricity use. Using previously discussed conversions, this corresponds to tons of CO2 per year and 1.1 tons of CO2 per year for electricity and non-electricity uses respectively. 1.5 Society The main non-private emitters of CO2 in the US are industry and agriculture. Combined, these emitted 2,018 million tons of CO2 in Per person in the US, this means 6.19 tons of CO2 per year. 1.6 Combined emissions For the activities examined in this report, the total CO2 emissions per year per capita are tons of CO2 per year. Of these, 28 tons of CO2 per year are related to uses that are personally controllable by the individual. 5