In the guide below, we consider which energy source might be the most sustainable (and eco friendly), and why.
Instead of providing one definitive answer to this question, we’ve provided a general summary, and we’ve also listed the various ways each major energy source used for electricity generation might be both sustainable, and non-sustainable.
Summary – Which Energy Source Is Most Sustainable?
Renewable energy sources like solar energy and wind energy not only use renewable resources, but they have little to no environmental footprint at the operation stage, and have no waste by-products resulting from energy to electricity conversion
These energy sources aren’t without their potential drawbacks though – there’s various sustainability concerns as well as practical drawbacks that might come with using these energy sources
Fossil fuels might be less sustainable across some of the different lifecycle stages (we list the reasons for this below)
It’s worth noting however that newer fossil fuel power plants might use technology and systems to reduce the environmental impact of the combustion of fossil fuels
Nuclear energy might sit somewhere in it’s own category of sustainability
It uses a finite resource (uranium), and produces spent nuclear fuel as a waste by-product at the operation stage
However, nuclear energy might also be reasonably clean at the operation stage – having little to no emissions and air pollutants
Inclusions & Exclusions In This Guide
Firstly, it’s important to outline what information we’ve either completely or partially included and excluded in this guide …
The main inclusions in this guide are:
– Sustainability relating to resource management and also the environment (environmental pollution, environmental degradation, and so on)
– Energy sources used for electricity generation
We’ve either partially or completely excluded the following factors in this guide:
– Economic sustainability (such as cost, impact on electricity prices, and so on)
– Practical considerations (such as power density, variability, and so on)
– Energy sources used as fuels (in transport for example), and energy sources used as gases (for heating for example)
In a separate guide, we consider which energy source is the ‘best’, and look at economic and practical factors as part of that guide.
The following two guides also specifically outline some economic and practical considerations for some of the different energy sources:
Fossil Fuels vs Renewables vs Nuclear Energy: A Comparison
Cost Of Renewable Energy vs Fossil Fuels vs Nuclear Energy
Assessing The Entire Lifecycle Of An Energy Source
Before we look at the individual energy sources, it’s worth pointing out that the entire lifecycle of an energy source should be assessed in order to identify where and how it might be sustainable.
Some of the key lifecycle stages for an energy source might include:
– The Extraction/Mining Of Resources
Do resources have to be mined/extracted for energy resources, or, for equipment and materials used by the energy source?
Mining has it’s own set of potential environmental issues to consider
– Refinement/Processing, Manufacture, Or Construction
What resources or materials are required, and what’s the environmental impact at these stages?
For example, solar and wind might not emit greenhouse gases during operation, but may have a carbon footprint for the manufacture of solar panels and wind turbines.
– Operation/Energy Generation
Is there any air pollution or emissions, or other types of environmental impact during the operational stage?
– Waste
Are there any direct waste by-products produced as a result of the operation stage? (e.g. fly ash, nuclear fuel) etc.
Are there and other types of discharge? (used thermal water from power plant cooling)
What about at the end of the lifespan of the energy generating equipment? – solar panels and other equipment have to be managed as waste at the end of their lifespan
– Other Things That Might Impact Sustainability
Aside from factors at the different stages, there might be miscellaneous factors that impact sustainability
One example of a factor might be how efficiently resources are converted into electricity, and how much original energy is wasted in the conversion of energy to electricity
Some renewable energy sources may be reasonably efficient at converting energy to electricity, whilst some fossil fuels and also biomass may be less efficient. This may make sense when considering the refining and energy conversion processes these energy sources have to go through compared to solar or wind for example
But, it might depend on whether energy is being converted for electricity, or for vehicle propulsion
There may be factors or variables that impact the sustainability of different energy sources in the future too.
In the future, we might consider the role and impact Artificial Intelligence technology and systems can play in more sustainably using or maximizing renewable energy for example
Something we haven’t mentioned above is sustainability factors at the consumer stage. Although some energy sources might be converted to electricity to be used, other energy sources like natural gas might be refined and then used as gas. There might be some consumer stage factors that impacts sustainability (such as how efficiently the gas is used) to consider here.
Sustainability Of Solar Energy
Some of the main sustainability features of solar energy might be:
Potential Sustainability Benefits
– Solar energy uses sunlight, which is considered a renewable resource
– The conversion of sunlight energy to electricity produces little to no emissions or air pollutants (in comparison to the combustion of some fossil fuels)
– The energy generation stage for solar energy doesn’t produce waste by-products like some fossil fuels might
Potential Sustainability Drawbacks
– Resources have to be extracted for the materials used for solar panels, as well as for supporting equipment such as storage batteries
– The manufacture of solar panels and supporting equipment has a sustainability footprint (they may for example use fossil fuels for the energy used in manufacturing processes)
– Solar panels that use plastic backing can use fossil fuels like petroleum for this plastic
– Solar panels and other equipment have to be managed as waste when they reach the end of their operational lifespan
– Some reports question whether solar panel farms contribute to land degradation issues
– In a power grid, solar energy may have to use backup energy sources, which can sometimes be fossil fuel energy sources. There’s obviously a sustainability footprint for these backup energy sources
– Some may question the scarcity of some metals and minerals used for variable renewable energy technology, such as lithium used in energy storage batteries. How much lithium is left to feed demand, as well as other metals, might be a question moving forward
Some Practical Considerations For Solar Energy
– Solar energy can be a reasonably flexible and versatile energy source in terms of where and how it can be installed and used (with different types and sizes solar panels, that can be used in urban areas and also remotely)
– Solar energy can also allow for multiple land uses. For example, solar panels can be installed on existing homes and commercial buildings
More Information On Solar Energy
Potential Pros & Cons Of Solar Energy
Sustainability Of Wind Energy
Potential Sustainability Benefits
– Wind energy uses wind, which is considered a renewable resource
– The conversion of wind energy to electricity produces little to no emissions or air pollutants (in comparison to the combustion of some fossil fuels)
– The energy generation stage for wind energy doesn’t produce waste by-products (like some fossil fuels might)
– Some reports indicate that wind energy might not be the threat to birds that other reports claim, and, wind energy may be one of the most wildlife friendly forms of energy overall
Potential Sustainability Drawbacks
– Resources have to be extracted for the materials used for wind turbines, as well as supporting equipment such as energy storage batteries
– The manufacture of wind turbines and supporting equipment has a sustainability footprint (they may for example use fossil fuels for energy used in manufacturing processes)
– Wind turbines can use lubricants and greases, which use fossil fuels like petroleum
– Wind turbine blades may sometimes be a hazard for flying wildlife whilst in use
– Wind turbines (specifically the turbine blades) and other equipment have to be managed as waste when they reach the end of their operational lifespan
– In a power grid, wind energy may have to use backup energy sources, which can sometimes be fossil fuel energy sources. There’s obviously a sustainability footprint for these backup energy sources
– Some may question the scarcity of some metals and minerals used for variable renewable energy technology, such as lithium used in energy storage batteries. How much lithium is left to feed demand, as well as other metals, might be a question moving forward
Some Practical Considerations For Wind Energy
– Wind energy can be installed both onshore, and offshore
– The space between wind turbines can be used for other uses, with farming being one example of another use. The land used for wind energy can therefore be used for multiple uses at once
More Information On Wind Energy
Potential Pros & Cons Of Wind Energy
Sustainability Of Hydro Energy
Potential Sustainability Benefits
– Hydro energy uses water, which is considered a renewable resource
– The conversion of water energy to electricity for some hydro energy setups produces little to no emissions or air pollutants (like the combustion of some fossil fuels can)
– The energy generation stage for hydro energy doesn’t produce waste by-products (like some fossil fuels might)
– Some pumped hydro energy projects may be able to act as a form of energy storage for surplus renewable energy in the future
Potential Sustainability Drawbacks
– Some hydro energy projects may have an environmental impact on natural water bodies (like rivers), and the local aquatic environment (and it’s wildlife)
– Some pumped hydro storage projects use fossil fuels to pump water up elevations, which may also result in emissions or the release of air pollutants
More Information On Hydro Energy
Potential Pros & Cons Of Hydro Energy
Sustainability Of Tidal Energy
Potential Sustainability Benefits
– Tidal energy uses water, which is considered a renewable resource
More Information On Tidal Energy
Potential Pros & Cons Of Tidal Energy
Sustainability Of Wave Energy
Potential Sustainability Benefits
– Wave energy uses water, which is considered a renewable resource
More Information On Wave Energy
Potential Pros & Cons Of Wave Energy
Sustainability Of Geothermal Energy
Potential Sustainability Benefits
– Geothermal energy uses the Earth’s heat/thermal energy, which is considered a renewable resource
– The conversion of heat energy to electricity produces little to no emissions or air pollutants (in comparison to the combustion of some fossil fuels)
– The energy generation stage for geothermal energy doesn’t produce waste by-products (like some fossil fuels might)
Potential Sustainability Drawbacks
– The use of geothermal energy can involve the release of both carbon dioxide and methane into the atmosphere
– Geothermal plants may involve both air pollution and water pollution/contamination
– Different types of hazardous or toxic substances can come from geothermal power plants
– Drilling (or hydraulic fracturing) to access geothermal energy specifically has been linked by some reports to some environmental and sustainability issues
More Information On Geothermal Energy
Potential Pros & Cons Of Geothermal Energy
Sustainability Of Bioenergy
Potential Sustainability Benefits
– Bioenergy uses biomass/organic matter, which is considered a renewable resource
Potential Sustainability Drawbacks
– Some types of biomass, such as dedicated bio crops, use resources (land, water, fertiliser, pesticide, and so on), may negatively impact the environment (via land conversion and land clearing, deforestation, land degradation, pollution, and more), and may have an opportunity cost in using that land and those resources for an alternate use (such as food production). There may be other consequences to bio crops too.
– The processing and refinement of biomass for bioenergy, biofuels, and biogas has a sustainability footprint
– The conversion of biomass to electricity can result in the emission of greenhouse gases, and the release of air pollutants
– The combustion of biomass for bioenergy may result in biomass ash residue, which might be considered a waste by-product
More Information On Bioenergy
Potential Pros & Cons Of Bioenergy
Sustainability Of Nuclear Energy
Potential Sustainability Benefits
– The use of nuclear fuel at nuclear reactors results in little to no emissions of greenhouse gases, and little to no air pollutants
Potential Sustainability Drawbacks
– Uranium is finite, and nuclear energy is considered a non renewable energy source
– Uranium has to be extracted/mined
– Uranium generally has to be processed and refined before it can be used as energy
– The site upon which nuclear power plants is built may require land clearing
– The construction of nuclear reactors requires construction material
– The use of uranium at nuclear reactors results in nuclear waste/spent nuclear fuel, which needs to be managed as waste
– Nuclear reactors can use a lot of water
– Nuclear power plants may be responsible for thermal water pollution (changing the temperature of water and discharging it
More Information On Nuclear Energy
Is Nuclear Energy Sustainable?
Potential Pros & Cons Of Nuclear Energy
Sustainability Of Fossil Fuel Energy Sources
Potential Sustainability Benefits For Fossil Fuels
– Some fossil fuel power plants can be fitted with devices and systems to manage or capture air pollutants, heavy metals and toxic substances, or carbon emissions from the operation of these power plants
New power plants may also be more efficient (at using coal), or have other features that improve sustainability
Potential Sustainability Drawbacks For Fossil Fuels
– Fossil fuels are finite, and are considered non renewable energy sources
– Fossil fuels have to be mined/extracted
– Fossil fuels generally have to be processed and refined before they can be used as energy
– The site upon which fossil fuel power plants are built may require land clearing
– The construction of power plants uses construction material
– The combustion of fossil fuels usually results in the emission of greenhouse gases, and the release of air pollutants (as well as heavy metals like mercury)
– wikipedia.org notes that (paraphrased), fossil fuels, particularly coal, contain dilute radioactive material (which is released into the environment when we burn large quantities of coal – unless we use systems to control and store/manage it), and also contain traces of toxic heavy elements like mercury and arsenic. Vaporised mercury may be emitted into the air.
– Some fossil fuel energy sources use a lot of water for cooling at thermal power plants
– Some once through thermal power plants may draw in the water they use, and in this process some aquatic life may be at risk
– Thermal power plants may also discharge water used for cooling at a higher temperature than the body of water that the discharged water is being discharged into – this is called ‘thermal pollution’, and it may impact the aquatic environment and the organisms living in it. watercalculator.org indicates that ‘… the main source of thermal pollution in rivers is cooling water from power plants’
– Power plants
Some Practical Considerations For Fossil Fuels As Energy
– Fossil fuels might traditionally have good power density, and be non-variable energy sources (i.e. they can deliver consistent and predictable power output) compared to some renewables
Coal Specifically
– Coal produces waste by-products such as fly ash. Sometimes fly ash can be recycled or reused in a commercial use, but, sometimes it becomes regular waste and is disposed of.
Natural Gas Specifically
– The extraction of natural gas can involve the leaking of methane into the atmosphere
Oil Specifically
– The transport of oil sometimes results in oil spills in the ocean
More Information On Fossil Fuels
Potential Pros & Cons Of Fossil Fuels
Potential Pros & Cons Of Coal Energy
Potential Pros & Cons Of Natural Gas Energy
Potential Pros & Cons Of Oil Energy
Sustainability Of Infrastructure For The Different Energy Sources
Something we haven’t discussed above is the supporting infrastructure for the different energy sources.
Infrastructure involves the supporting equipment and technology that helps generate, transport and distribute power.
The sustainability footprint of infrastructure used for the different energy sources might be different.
Just one example of this might be the land footprint of the different energy sources.
Fossil fuel and nuclear energy sources might be more land efficient when considering their power density compared to renewables.
However, when including upstream infrastructure like gas pipelines and other fossil fuel related infrastructure, fossil fuel energy’s land footprint might increase.
So, infrastructure is an important consideration for the different energy sources.
List Of Potential Sustainability Factors To Take Into Consideration For Different Energy Sources
– Is the resource being used finite, or, is it an abundant or renewable resource?
If finite, how many years proven reserves are left, and what is the potential for future proven reserves to be confirmed?
– Is there mining or extraction involved to obtain the resource?
– What resources are used in production, refining and other lifecycle stages before energy generation?
Water, land, fertilizer/pesticides, energy (used in manufacture for example), and so on
– Is water or any other resource or input used during energy generation?
Thermal power plants can use water for cooling for example
– What are the environmental effects of the entire lifecycle?
i.e. environmental pollution, environmental degradation, impact on wild life and habitats, and other environmental issues
From emissions, air pollutants, water pollution, land degradation, waste pollution, and so on
Some issues even develop, such as air pollutants contributing to smog or acid rain
– Are any waste by-products produced?
Such as fly ash, spent nuclear fuel, and other types of waste
– Can any materials and waste be recycled or commercialised?
– How efficiently are resources turned into electricity?
This may impact the efficient use of resources
– Are there any environmental toxicity risks or hazardous risks involved in using the energy source?
From spills, from leaching of materials and substances, from pollutants, and so on
Heavy metals like mercury can be another potential hazard
More Information On The Potential Sustainability Impact Of Different Energy Sources
These guides contain more information on the potential sustainability impact of different energy sources:
Potential Impact Of Different Energy Sources On Different Aspects Of Society
Carbon Footprint Of Each Energy Source
Which Energy Source Is The Most Harmful, & Which Is Safest? (contains more information on air pollutants, and carbon emissions)
Water Footprint Of Each Energy Source
Sources
1. Various ‘Better Meets Reality’ guides
2. https://www.watercalculator.org/water-use/the-water-footprint-of-energy/
3. https://en.wikipedia.org/wiki/Environmental_impact_of_electricity_generation
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