Key takeaways:
- Identifying optimal methods of energy production is necessary to steer future investments in sustainable energy
- Bringing together data on several metrics of interest can facilitate comparisons between energy sources and help to demystify the energy debate
- Data on emissions, danger, land use, building materials, and costs was compiled to illustrate trade-offs between seven common energy sources
Energy Production The creation of energy for electricity, transportation, and heating.
As nations around the world seek to adopt sustainable methods of energy production, governments and citizens are debating over which energy sources are best suited for the task. The answer to this question is crucial, as major investments made now will impact energy generation for several decades to come.
While there is no perfect energy source, it is possible to compare viable energy production options to get a better picture of which have the fewest disadvantages. Comparing energy sources is extremely complicated, as energy production issues are multidimensional and highly value-driven. However, bringing together data on several metrics of interest can facilitate comparisons, helping to demystify the energy debate.
Data on five different metrics was compiled for seven common energy sources (biomass, coal, hydropower, natural gas, solar, and wind), using lifecycle values to make comparisons possible between different energy sources with different structural life spans and generation capabilities.
Lifecycle Values A measure of the average impacts of energy production for a generating plant over its lifetime.
| Energy Source | Explanation | % Global Energy |
|---|---|---|
| Coal | Burning coal to produce steam which drives a turbine | 25% |
| Natural Gas | Burning non-renewable hydrocarbon gas to drive a turbine | 23% |
| Biomass | Burning plant matter to produce steam and drive a turbine | 7% |
| Hydropower | Capturing energy from moving water to drive a turbine | 6% |
| Nuclear | Using fission energy to produce steam and drive a turbine | 4% |
| Wind | Capturing energy from wind to drive a turbine | 2% |
| Solar | Absorbing sunlight in PV cells to create electrical charge | 1% |
Due to a lack of available data on battery storage, all comparisons made for solar and wind energy only represent the impacts and costs associated with intermittent usage. In other words, the values are only accurate for for a form of solar and wind energy that would need to be paired with a non-intermittent energy source to provide sufficient energy to the grid.
Intermittent Energy Energy that is not continuously available due to uncontrollable external factors.
How do these energy sources compare?
Emissions
Using data compiled by Our World in Data, it can be shown that nuclear energy produces the lowest emissions per unit of energy generated over its lifecycle, with wind and solar close behind. The variation in the estimates for biomass emissions is caused by differences in which plant matter is being burn. For example, burning excess crops produces less emissions than burning trees.
| Energy Source | Emissions (Tonnes CO2eq per GWh) |
|---|---|
| Nuclear | 3 |
| Wind | 4 |
| Solar | 5 |
| Hydropower | 34 |
| Biomass | 78-230 |
| Natural Gas | 490 |
| Coal | 820 |
Danger
Again using data compiled by Our World in Data, it is evident that solar, hydropower, wind, and nuclear are all associated with very few deaths per unit of energy generated over their lifecycle. Notably, the estimates for nuclear energy include all deaths related to the Chernobyl and Fukushima disasters, as well as occupational accidents from mining and milling.
| Energy Source | Danger (Deaths per TWh) |
|---|---|
| Solar | 0.02 |
| Hydropower | 0.02 |
| Wind | 0.04 |
| Nuclear | 0.07 |
| Natural Gas | 2.8 |
| Biomass | 4.6 |
| Coal | 24.6 |
Land Use
A report commissioned by the United Nations Convention to Combat Desertification reveals that nuclear energy and natural gas require the least amount of land per unit of energy generated over their lifecycle. Again, the variation for biomass estimates is caused by differences in which plant matter is being burn.
| Energy Source | Land Use (m2 per MWh) |
|---|---|
| Nuclear | 0.1 |
| Natural Gas | 0.2 |
| Wind | 1 |
| Coal | 0.2-5.0 |
| Hydropower | 10 |
| Solar | 10-15 |
| Biomass | 0.1-500 |
The graph can be recreated with biomass excluded to better compare the land use of other energy sources.
Building Materials
Energy production plants that require more materials to build can be more vulernable to supply chain shocks or shortages. The U.S. Department of Energy provides a breakdown of the materials required, on average, for each unit of energy generated over the plant’s lifecycle. Building natural gas, nuclear, biomass, and coal facilities require substantively less building materials per unit of energy generated over their lifecycle.
| Materials (Ton per TWh) | Natural Gas | Nuclear | Biomass | Coal | Wind | Hydropower | Solar |
|---|---|---|---|---|---|---|---|
| Aluminum | 1 | 0 | 6 | 3 | 35 | 0 | 680 |
| Cement | 0 | 0 | 0 | 0 | 0 | 0 | 3,700 |
| Concrete | 400 | 760 | 760 | 870 | 8,000 | 14,000 | 350 |
| Copper | 0 | 3 | 0 | 1 | 23 | 1 | 850 |
| Glass | 0 | 0 | 0 | 0 | 92 | 0 | 2,700 |
| Iron | 1 | 5 | 4 | 1 | 120 | 0 | 0 |
| Lead | 0 | 2 | 0 | 0 | 0 | 0 | 0 |
| Plastic | 0 | 0 | 0 | 0 | 190 | 0 | 210 |
| Silicon | 0 | 0 | 0 | 0 | 0 | 0 | 57 |
| Steel | 170 | 160 | 310 | 310 | 1,800 | 67 | 7,900 |
Cost
Finally, the U.S. Energy Information Administration provides data on the costs of energy production. Solar energy without battery storage beyond four hours is by far the cheapest per unit of energy generated over its lifecycle.
The range in costs for wind power is because offshore wind is substantially more expensive than onshore wind. For natural gas, the range in costs is because combustion turbine generators are substantially more expensive than combined cycle power plants. Note that all values exclude tax credits.
| Energy Source | Cost (Dollars per MWh) |
|---|---|
| Solar | $32.78-$47.67 |
| Hydropower | $55.26 |
| Coal | $72.78 |
| Nuclear | $76.88 |
| Biomass | $89.21 |
| Natural Gas | $37.11-$106.62 |
| Wind | $36.11-$120.50 |
Importantly, solar energy without a longer duration of energy storage cannot be used to meet grid demand at all times. When the costs of battery storage are considered, the range of possible costs for solar energy increases considerably.
Why weren’t additional energy metrics chosen?
Beyond the above categories, there are multiple addition areas of concern related to energy production including. For instance, waste generation is a concern, especially for nuclear energy. However, it is very difficult to compare waste products as a single metric as some are produced as a solid (nuclear) while others are vented into the atmosphere (as is the case with biomass, natural gas, and coal). Further, some waste products are highly regulated, like nuclear, while others have less established methods of disposal.
Likewise, political opposition to implementing the energy source would be interesting to illustrate, but little data is available and public opinion is generally not consistent across regions.
Energy capacity and reliability could also be considered, though unlike the other metrics chosen, this would require higher values to be interpreted as “good” and lower values as “bad”, which might make interpretation of the graph difficult.
So, which energy source has the fewest disadvantages?
Ultimately, there is no perfect energy source. Every method of producing energy has disadvantages that require value-driven guidance on which trade-offs are tolerable. Further, geographic, operational, and resource constraints will also limit which energy sources can feasibly be implemented in a given region.
Nonetheless, comparing energy disadvantages side-by-side can simplify this multidimensional problem and serve as a platform for discussion in the energy transition debate.
All data and code for this analysis can be found here.