How Much Electricity Does an Electric Car Use - Part 2
Photograph (CC0) by Theodor Vasile, cropped by Larry Neal Gowdy
Copyright ©2021 - May 25, 2021
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BTU and Emissions Calculations
National Electricity Consumption
BTU and Emissions Calculations
1kWh of electricity equals about 3,412 BTUhr. 250kWh of electricity equals about 853,050 BTU. For ease of use and for initial generalizations, 853,050 BTU equals about 85.3% of one mmBtu (million-BTU) of LNG.
As per the EPA, CO2 emissions (molecular reactions) per mmBtu of natural gas is about 117 pounds. Therefore, 85.3% of 117 sums to about 99.8 pounds of CO2 are emitted per 250kWh of electricity generation.
As per the EPA, CO2 emissions (molecular reactions) per mmBtu of gasoline is about 19.6 pounds per gallon (as references explain, the weight of a gallon of gasoline is about 6.3 pounds, but when the hydrogen and carbon atoms are separated during combustion, they then recombine with oxygen atoms, thus creating heavier molecules). At about 114,000 BTU per gallon of gasoline, about 8.77 gallons of gasoline will produce 1 mmBtu, and emit (cause through molecular reactions) about 172 pounds total CO2.
250kWh of generated electricity may enable an electric car to travel approximately 220 miles at highway speeds (without use of an electric heater, air conditioner, nor any other high wattage accessory) while emitting (causing) about 99.8 pounds of CO2 (along with the release of methane from wells and handling, which traps about 90 times more heat than CO2), plus consuming about 500 gallons of water. Common reported averages of mileage for a 50kWh electric battery are closer to 190 miles, but the emissions and water loss would remain similar.
A gasoline powered economy car at about 35 miles per gallon for 220 miles at highway speeds will consume about 6.3 gallons of gasoline (while with use of a heater, air conditioner, and other accessories), and emit about 123 pounds of CO2.
A gasoline powered economy car at about 40 miles per gallon for 220 miles at highway speeds will consume about 5.5 gallons of gasoline (while with use of a heater, air conditioner, and other accessories), and emit about 108 pounds of CO2, which is very similar to electric cars.
At 22,000 miles a year, an electric car emits about 9,980 to 11,579 pounds of CO2 while consuming about 55,000 gallons of water. For the same distance, the economy gasoline powered cars would emit about 12,300 and 10,800 pounds of CO2 while not consuming additional water.
Coal emits approximately 80% to 90% more CO2 per mmBtu than natural gas, while coal also requires approximately 150% more water than natural gas. Based upon the example above, if an electric car were recharged from a coal powered plant, then the electric car would emit approximately 18,000 to 22,000 pounds of CO2 annually, plus consume about 82,500 gallons of water. Electric cars charged by coal powered plants would emit over twice the CO2 as would be emitted by an economy gasoline powered car.
Hydroelectric does not require fossil fuels, but the water consumption is approximately 32.6 times more than natural gas. 55,000 gallons times 32.6 sums to about 1,793,000 gallons of fresh water consumed annually by each individual electric car. Damming rivers also has the consequences of destroying the environment downstream.
As a general whole, and within real-world scenarios, economy gasoline cars are able to emit similar or less global warming CO2 than electric cars, plus do so without straining the national grid, and without depleting precious national water supplies.
Quick Water Data
"Gas combustion turbines and internal combustion engines do not require cooling water and were assigned WCFs (water consumption factors) of zero. WCFs of 0.39 and 0.21 gal per kWh were estimated for steam turbine and combined cycle power plants by aggregating technology shares and WCFs... The thermoelectric power generation pathways consume more than twice the water of fossil fuel pathways primarily for waste heat dissipation. ...('well to wheels' water consumption per mmBtu as per figure 11): gasoline 120, ethanol (corn) 1,098, electricity (coal) 256, electricity (natural gas) 164, electricity (nuclear) 268, electricity (hydro-power) 5,354." (Wells-to-Wheels: Water Consumption for Transportation Fuels in the United States, by David J. Lampert, Hao Cai, and Amgad Elgowainy).
From well to finished product, the OSTI reports that the life cycle of water consumption associated with gasoline averages around 46 gallons of water per mmBtu. Well to Wheels states 120 gallons of water per mmBtu.
If one gallon of gasoline has about 114,000 BTU, then it requires about 8.77 gallons of gasoline to produce one mmBtu. 46 gallons of water (as per OSTI) divided by 8.77 gallons of gasoline sums to about 5.3 gallons of water being consumed per gallon of gasoline.
If Well-to-Wheels is more correct, then 120 gallons of water divided by 8.77 gallons of gasoline sums to about 13.68 gallons of water consumed per gallon of gasoline.
The same OSTI report states that thermoelectric generation with natural gas averages around 79 gallons of water per mmBtu. Well-to-Wheels shows 164 gallons of water per mmBtu.
Comparing OSTI and Well-to-Wheels sums, one mmBtu of gasoline (as per OSTI) consumes 5.3 gallons of water, or else, (as per Well-to-Wheels) one mmBtu of gasoline consumes 13.68 gallons of water. One mmBtu of electricity from natural gas (as per OSTI) consumes 79 gallons of water, or else, (as per Well-to-Wheels) one mmBtu of electricity from natural gas consumes 164 gallons of water.
As per OSTI's ratio of 5.3 and 79, the sum is that natural gas consumes about 14.9 (1,490%) times more water than a similar mmBtu from gasoline. As per Well-to-Wheels' ratio of 13.68 and 164, natural gas consumes about 12 times (1,200%) more water than a similar mmBtu from gasoline.
Of the many dozens of other research sources seen, the water consumption ratio of 12 natural gas to 1 gasoline remains to be the closest estimate.
Also, due to numerous evaluations of how OSTI and Well-to-Wheels presented their information, Well-to-Wheels' data is favored.
Where does the evaporated water go? Typically, the vapor would follow the winds. West winds would carry the vapor towards the east. Regions that are east of waterless deserts will not receive the vapor, and thus the water evaporated from the regions may be permanently lost. About fifteen years ago, and based upon available statistics of water consumption, it appeared that the quantity of fresh water being consumed globally from ground and underground resources was near the quantity of water that was being reported to be rising in oceans. If the speculated estimate were given further investigation, and if verified as plausible, then the oceans may not be rising because of global warming, but rather might — in part — be rising because of inland water use, including electricity production.
The consequences of electricity production do not begin and end at power plants.
National Electricity Consumption
Annually, the USA is reported to currently consume approximately around 4,200-teraWatt-hours (4,200 million-million watt-hours).
At 8,760 hours in a year, times about 331-million people in USA, sums to about 2,899,560-million hours.
An annual electricity production of about 4,200,000,000,000,000 watt-hours sums to approximately 12,688,821.7 watt-hours consumed per person. 12,688,821 divided by 8,760 hours a year, sums to about 1448 continuous watt-hours.
The quantity of electricity is similar to everyone in the USA using a 1250 watt electric range burner and 5 each 40-watt light bulbs 24 hours a day every day. A family of four would be similar to having all four burners on an electric range at maximum heat and with 20 each 40-watt light bulbs on all day every day.
As a whole, electric power plants in the USA are reported to withdraw a little over 40% of all water used in the USA, which is similar to the quantity of water that is withdrawn by agriculture. Different government agencies give different numbers, but the reported totals of water withdrawn for electricity production range from around 133-billion to 322-billion gallons of water withdrawn daily (with most of the heated water being returned to the sources). According to the USGS in 2015, 15 gallons of water was used to produce 1 kWh of electricity (which is about 225% higher than the averages from Well-To-Wheels).
If about 500 gallons of water are consumed to provide 75kWh of electricity to recharge an electric car's 50kWh battery, and if the batteries must be recharged every three days, then on the average, the electric cars would consume about 167 gallons of water daily. If electric cars were to replace all gasoline vehicles in the USA, resulting in there being about 300-million electric vehicles in the USA, then the quantity of water used would be around 50-billion (50,000,000,000) gallons of water consumed daily by electric cars alone. If most all diesel powered vehicles were also replaced with electric vehicles, then the sum might increase to around 100-billion gallons or more of fresh water consumed by electric vehicles each and every day.
Humidity retains heat. More steam increases humidity. Increased humidity equates to global warming.
How Much Electricity Does an Electric Car Use - Part 3 summarizes the impact that energy production has upon the environment, while also lightly touching on the misinformation commonly given by government and online sources.