Low-carbon is a lifecycle statement
Nuclear, wind, the lower-impact hydro case and CdTe PV are all below 14 kg CO₂-eq/MWh in the European scenarios. Their remaining emissions arise mainly outside direct electricity generation.
Drawing No. EH–ES–011 // Environmental & Safety Engineering
Electricity Life-Cycle Emissions by Source
Reviewed August 2026
Compare nuclear, coal, natural gas, carbon capture, hydropower, wind and solar on one consistent cradle-to-grave basis: 1 MWh of electricity delivered to the grid.
Source UNECEFull dataset Europe (EU28)Reference year 2020Indicator Total climate changeUnit kg CO₂-eq/MWh
These are scenarios, not universal constants. Technology design, resource quality, manufacturing mix, lifetime, capacity factor and site conditions can change results. Use the matched configuration and regional range—not a generic family label.
European life-cycle climate results
UNECE Table 14 · exact scenarios
| Rank | Technology scenario | EU result | Matched 12-region range | Configuration note |
|---|---|---|---|---|
| 1 | Nuclear — average | 5.29 | 5.1–6.4 | UNECE average nuclear scenario |
| 2 | Hydropower — 360 MW | 10.7 | 6.1–11 | Lower-impact hydro scenario; not generic hydro |
| 3 | Solar PV — CdTe | 11.9 | 8–28 | Ground-mounted cadmium-telluride PV |
| 4 | Wind — onshore | 12.4 | 7.8–16 | Onshore wind configuration |
| 5 | Wind — offshore | 13.3 | 12–21 | Steel-foundation offshore configuration |
| 6 | Concentrated solar — tower | 21.7 | 14–87 | Tower, not CSP trough |
| 7 | Solar PV — poly-Si | 36.7 | 23–82 | Ground-mounted polycrystalline-silicon PV |
| 8 | Natural gas NGCC + CCS | 128 | 91–221 | Combined-cycle gas with carbon capture |
| 9 | Hydropower — 660 MW | 147 | 85–147 | Higher-impact reservoir scenario |
| 10 | Hard coal PC + CCS | 369 | 213–470 | Pulverized coal with carbon capture |
| 11 | Natural gas NGCC | 434 | 403–513 | Combined-cycle gas without CCS |
| 12 | Hard coal PC | 1,020 | 912–1,095 | Pulverized coal without CCS |
Units: kg CO₂-equivalent per MWh delivered to the grid. EU results are Table 14 values converted from kg CO₂-eq/kWh. Regional intervals are configuration-matched minimum–maximum results across the 12 regions modelled by UNECE [1].
What the table shows
Evidence without a universal winner claim
CCS reduces—but does not eliminate—climate impact
Gas NGCC falls from 434 to 128 kg CO₂-eq/MWh with CCS in these scenarios; hard coal PC falls from 1,020 to 369. Residual emissions, upstream fuel supply and the energy penalty remain.
Technology variants matter
Poly-Si and CdTe PV are not interchangeable, CSP tower is not CSP trough, and offshore foundation type matters. A family average can conceal the configuration actually modelled.
Hydropower is highly site-sensitive
The two European hydro scenarios differ from 10.7 to 147 kg CO₂-eq/MWh. Reservoir characteristics, biogenic emissions, construction and electricity output can dominate the result.
What “life-cycle emissions” includes
Beyond the power-plant stack
MaterialsExtraction and processing of fuels, metals, concrete and other materials.
ManufacturingModules, turbines, reactors, foundations, fuel conversion and fabrication.
ConstructionTransport, civil works, site preparation and plant installation.
OperationDirect emissions, maintenance, replacement and fuel-cycle processes.
End of lifeDecommissioning, dismantling, waste treatment and recycling assumptions.
Climate impact = Σ (inventory greenhouse-gas flow × characterization factor) / delivered electricity
The result is total climate-change potential in CO₂-equivalent, not only carbon dioxide emitted during plant operation. Read the methodology and system-boundary guide before combining figures from different studies.
Why regional results change
Same label · different lifecycle system
Manufacturing electricityCarbon intensity affects PV modules, metals, enrichment and equipment production.
Resource qualitySolar irradiation, wind speed and fuel grade change lifetime energy or upstream processing.
Capacity factorMore lifetime electricity spreads fixed construction impacts over more MWh.
Plant lifetimeLonger operation can reduce fixed impacts per MWh when replacements remain controlled.
Technology configurationCapture system, mounting, foundation, cooling and plant design affect inventory.
Site-specific processesReservoir emissions, transport distances and methane leakage can dominate some cases.
Why climate change is not the whole LCA
Carbon is one of 15 modelled indicators
A climate-only comparison is useful and highly searchable, but it cannot establish the lowest overall environmental burden. The same UNECE study also reports acidification, particulate matter, eutrophication, toxicity, ionising radiation, dissipated water and resource-use indicators. The impact-category guide explains those measures, and the interactive LCA tool compares all 15 without hiding trade-offs behind one score.
Frequently asked questions
Five climate-comparison checks
Which electricity source has the lowest life-cycle emissions in this dataset?
In the UNECE European scenarios shown here, nuclear has the lowest central result at 5.29 kg CO₂-equivalent per MWh. This is a scenario-specific result, not a universal technology constant.
Are life-cycle emissions the same as power-plant stack emissions?
No. Life-cycle emissions include upstream fuel and material supply, construction, operation and end-of-life processes inside the declared boundary.
Why do solar, wind and hydropower emissions vary by region?
Manufacturing electricity, resource quality, capacity factor, plant lifetime, technology configuration and site-specific conditions change the lifetime electricity denominator and supply-chain inventory.
Does carbon capture make coal and gas zero-carbon?
No. In these scenarios CCS reduces climate impact but residual direct emissions, upstream fuel supply, added energy use and infrastructure remain.
Do these figures include storage and grid backup?
No. They compare generation technologies within the UNECE plant-level boundary. Storage, curtailment, balancing and additional grid infrastructure require a broader electricity-system assessment.
References
Data and methodological basis
- UNECE, Life Cycle Assessment of Electricity Generation Options, March 2022 edition—Table 14 and regional climate figures.
- UNECE corrigendum, July 2022.
- ISO 14040:2006, Life-cycle assessment — Principles and framework.
- ISO 14044:2006, Life-cycle assessment — Requirements and guidelines.
- European Commission JRC, European Platform on Life Cycle Assessment and ILCD resources.
Continue the LCA analysis
Interconnected EngineerHub resources
Reviewed 27 August 2026 · Values reconciled to UNECE Table 14 and matched regional configurations