Which Fossil Fuel Emits The Most CO2 & Greenhouse Gases?

We’ve already put together a guide on the carbon footprint of the different and main energy sources 

But, this guide is specifically about the carbon footprint of the different fossil fuel energy sources

We specifically look at emission rates, which fossil fuels emit the most CO2 globally, and also in the two (currently) highest emitting countries – China, and the United States.

 

Summary – Fossil Fuel That Emits The Most CO2 & Greenhouse Gases

 

Which Fossil Fuel Emits The Most

Coal is the fossil fuel that emits the most CO2 overall, both in total, and on an emissions rate basis per unit of electricity produced

It’s worth mentioning though that emissions totals can vary country by country, and year to year, as countries change the quantities of the energy sources they use

 

Global Total Emissions

Globally, in terms of total tonnes of CO2 emissions, coal followed by oil emit the most greenhouse gases right now

 

China Total Emissions

In China, coal emits the most total tonnes of CO2 emissions by far right now

 

United States Total Emissions

In the United States, oil emits the most total tonnes of CO2 emissions, followed by gas and coal

 

Emissions Per Kilowatt Of Electricity Produced

For electricity production (when measuring CO2 emitted per kilowatt hour produced)

One set of data indicates coal emits the most (at 2.2 pounds), followed by oil (2 pounds), and natural gas the least (at 0.9 pounds)

Another set of data indicates coal emits almost double the greenhouse gases of natural gas

 

Emissions Just From The Combustion Stage

When looking at just the combustion stage, one source indicates that natural gas emits about 50 or 60% less than coal

 

Considering The Total Lifecycle Of A Fossil Fuel

Apart from looking at just emissions from combustion of fossil fuels, there’s the emissions across the entire lifecycle of a fossil fuel to consider.

When we take into account full lifecycle emissions, as one example, natural gas may involve the leakage of methane at the drilling and extraction stage, which should be accounted for. Some sources indicate emissions at the mining stage can be 1 to 9% of total lifecycle emissions

When looking at the lifecycle emissions footprint of electricity production …

One set of data had conventional coal combustion as the highest emitter, followed by newer coal gasification plants, oil fired electricity generation plants, and then current gas powered electricity generation 

Another set of data had coal PC as higher emitting than combined cycle gas 

But, the exact inclusions in these life cycle calculations should be considered to see exactly what factors the calculations are made up of.

 

Emissions In Transport

When only taking into account tailpipe emissions (where about 80% of emissions take place for a car), natural gas emits about15 to 20 percent less than gasoline when burned in today’s typical vehicle

Diesel emits more per gallon than gasoline, but has better fuel efficiency/mileage

Petroleum based products and fuels are responsible for the most overall emissions.

 

Variables In Calculating Fossil Fuel Emissions

Variables when calculating emissions from fossil fuels include but aren’t limited to leakage rate, the power plant or other combustion technology and carbon capture devices used, the energy conversion efficiency, and other factors.

 

Fossil Fuel Emissions vs Renewables, Nuclear & Other Energy Sources

This guide outlines the carbon footprints of different energy sources.

 

Most Global CO2 Emissions By Fuel Source

According to a 2013 set of data, coal emitted 15.15 billions of tonnes of CO2 per year, liquid oil 11.79, and natural gas 6.62.

See the full global CO2 emissions by energy source figures in this guide.

 

CO2 Emissions In China By Fuel Source

Coal by far led China’s CO2 emissions in 2016 in terms of gigatonnes of CO2.

Coal was at 7.17Gt of CO2, oil 1.38 and gas at 0.395.

See the full Chinese CO2 emissions by energy source figures in this guide.

 

CO2 Emissions In The United States By Fuel Source

Oil led the United States CO2 emissions in 2016 in terms of gigatonnes of CO2.

Oil was at 2.31Gt CO2, gas at 1.53Gt CO2, and coal at 1.38Gt CO2.

See the full United States CO2 emissions by energy source figures in this guide.

 

CO2 Emissions In Japan By Fuel Source

[In Japan, coal] constitutes 38.2 percent of Japan’s CO2 emissions – an almost even split with oil, which accounts for 37.3 percent

– chinapower.csis.org

 

Emissions Per Kilowatt Of Electricity Produced

Per kilowatt hour of electricity produced …

One set of data indicates emissions from electricity generation are – Coal releases 2.2 pounds, petroleum releases 2.0 pounds, and natural gas releases 0.9 pounds.

Another set of data indicates coal [emits about] 2.15 lbs of CO2 per kWh electricity [and natural gas is at] 1.22 lb of CO2

Renewables and nuclear essentially have almost no emissions during electricity generation.

Read more about emissions per unit of electricity produced of the different energy sources in this guide.

 

CO2 Emissions Just For Combustion

Natural gas emits 50 to 60 percent less carbon during the combustion process [than coal]

– chinapower.csis.org

 

Natural gas is a fossil fuel, though the global warming emissions from its combustion are much lower than those from coal or oil

Natural gas emits 50 to 60 percent less carbon dioxide (CO2) when combusted in a new, efficient natural gas power plant compared with emissions from a typical new coal plant.

– ucsusa.org

 

Lifecycle Emissions Of Different Fossil Fuels

Apart from combustion, there’s the mining and extraction of fossil fuels to take into account when getting an idea of full life cycle emissions.

 

In terms of lifecycle emissions for the different fossil fuels:

One set of data had conventional coal combustion as the highest emitter (at 1000g of CO2e/kWh), followed by newer coal gasification plants (800), oil fired electricity generation plants (650), and then current gas powered electricity generation (500)

Another set of data had coal PC as higher emitting than combined cycle gas

 

… with natural gas, the drilling and extraction of natural gas from wells and its transportation in pipelines results in the leakage of methane

… Preliminary studies and field measurements show that these so-called “fugitive” methane emissions range from 1 to 9 percent of total life cycle emissions

Whether natural gas has lower life cycle greenhouse gas emissions than coal and oil depends on the assumed leakage rate, the global warming potential of methane over different time frames, the energy conversion efficiency, and other factors

– ucsusa.org

 

Miscellaneous factors like the type of power plant (an older dirtier coal power plant vs a newer coal power plant with carbon capture technology for example) also matter.

 

Fossil Fuel Emissions In Transport

Petroleum based products emit the most total emissions.

Natural gas appears to be cleaner than petroleum based fuels.

Diesel emits more than gasoline, but has better efficiency.

 

Considering only tailpipe emissions, natural gas also emits 15 to 20 percent less heat-trapping gases than gasoline when burned in today’s typical vehicle

– ucsusa.org

 

Diesel emits more per gallon than gasoline, but has better fuel efficiency/mileage

 

Sources

1. https://chinapower.csis.org/china-greenhouse-gas-emissions/

2. https://www.ucsusa.org/clean-energy/coal-and-other-fossil-fuels/environmental-impacts-of-natural-gas#.W9AW9BMzbR1

3. https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions

4. https://www.bettermeetsreality.com/carbon-footprint-of-common-everyday-things-products-foods/

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