Different energy and electricity production sources/methods are going to emit different amounts of carbon.
This can be directly, or indirectly throughout the lifecycle of the energy production method.
In this guide, we look at how much carbon coal, gas, nuclear, solar, wind and others emit.
Summary – Carbon Footprint Of Different Energy/Electricity Production Sources
Energy sources can emit greenhouse gases not only directly at the combustion stage, but indirectly also across the whole lifecycle of sourcing and using the energy source.
One example of this the potential for indirect methane leaks when mining oil or gas, in addition to direct emissions when burning oil or gas products when using them for energy a the operation stage
There’s various ways to measure the carbon footprint of different energy sources
You can measure total emissions in terms of quantity (tonnes), and also break that down into a % share of total emissions for a country, or on a global scale. For example, in the US in 2017, majority of carbon emissions came from coal followed by natural gas, at 69% and 29% respectively
Another way to measure it is by the pounds of carbon emitted per kWh electricity produced
When taking this into account, coal tends to be the heaviest emitter, followed by oil and natural gas at two third to half of the per kWh hour value of coal.
Renewables tend to produce minimal emissions or almost no emissions at the operation stage (although there emissions involved in making equipment such as solar panels, wind turbines, and so on)
The type of plant used to produce electricity (e.g. new vs old coal power plant) and emissions control technology installed at a plant can have an impact on emissions
Something else that might be considered is black vs brown coal, and their respective emissions
How Does Energy & Electricity Production Emit Carbon & Other Greenhouse Gases
There’s usually two ways:
Directly – through the burning/combustion of fossil fuels (primarily)
Indirectly – includes greenhouse gases emitted through the lifecycle of generating the energy and not just directly at the energy production stage e.g. manufacturing solar panels creates emissions in fabrication through sourcing materials, and putting together the panels themselves, the frames etc. Another example is the potential for methane leaks at the oil and gas mining stage
How Much Carbon Electricity & Energy Sources Emit In The United States
In 2017, CO2 emissions from U.S. electric power sector by source were:
- Coal – 1207 million metric tons, and 69% of total emissions
- Natural Gas – 506, and 29%
- Petroleum – 19, and 1%
- Other – 12, and less than 1%
Emissions of carbon dioxide (CO2) by the U.S. electric power sector were 1,744 million metric tons, or about 34% of the total U.S. energy-related CO2 emissions of 5,140 million metric tons.
Breakdown Of Total Energy Generation By Source, In The US
In 2017 in the United States:
- 63% of … electricity generation was from fossil fuels (coal, natural gas, petroleum, and other gases).
- About 20% was from nuclear energy
- … and about 17% was from renewable energy sources.
Carbon Footprint Of Different Energy/Electricity Sources
- Coal generally requires more water than nuclear, and generates more greenhouse gases emissions and other pollutants than any other energy source (about 2.15 lb CO2 per kWh electricity)
- Natural gas emits about half the carbon emissions of coal (about 1.22 lb CO2 per kWh electricity) and requires less water than coal, but still needs an enormous amount of water for drilling activities and conversion to electricity
- Wind and solar energy consume little to no water and generate negligible carbon emissions
The Life cycle CO2 equivalent (including albedo effect) from selected electricity supply technologies .. arranged by gCO2eq per kWh (CO2 equivalent per kilowatt hour of electricity supplied) in median values … are:
- Coal – 820 (median gCO2eq per kWh)
- Biomass (co-firing with coal) – 740
- Gas (combined cycle) – 490
- Biomass (dedicated) – 230
- Solar PV (utility scale) – 48
- Solar PV (rooftop) – 41
- Geothermal – 38
- Concentrated Solar Power – 27
- Hydropower – 24
- Wind Offshore – 12
- Nuclear – 12
- Wind Onshore – 11
As we can see, coal comes out rated worst, whilst most of the renewables have lower lifecycle emissions.
In the UK, the lifecycle carbon footprint of different energy production sources is:
- Conventional Coal Combustion – [results in emissions of the order of] >1,000 gCO2eq/kWh (CO2 equivalent per kilowatt hour)
- Newer gasification plants – <800gCO2eq/kWh
- Oil-fired electricity generation plants – ~650gCO2eq/kWh
- Current gas powered electricity generation – ~500gCO2eq/kWh)
- Biomass (combustion of low density miscanthus) – 93gCO2eq/kWh
- Photovoltaic power systems (in UK) – 58gCO2eq/kWh
- Photovoltaic power systems (in Europe) – 35gCO2eq/kWh (because there is more sunlight, so overall operating hours are greater and energy output is higher)
- Wave & Tidal – 25-50gCO2eq/kWh
- Biomass (gasification of higher density wood-chip) – 25gCO2eq/kWh
- Hydro (storage scheme) – ~10-30gCO2eq/kWh
- Offshore Wind – 5.25gCO2eq/kWh
- Nuclear Power Generation – ~5gCO2eq/kWh
- Hydro (run of river scheme) – <5gCO2eq/kWh
- Onshore Wind – 4.64gCO2eq/kWh
More lifecycle carbon footprint stats of different energy sources can be found at wikipedia.org (in the table under the ‘water usage’ section.
Trends Of Emissions By Energy & Electricity Production In The US, and Potential Solutions To Decrease Emissions
Read more at epa.gov