Nuclear power is dirty, dangerous and expensive; not carbon-free; and encourages nuclear proliferation. A nuclear power station itself does not emit greenhouse gasses like CO2. Yet nuclear power contributes to climate change; with every step in the whole fuel chain, needed to generate electricity in the end, many energy is used. For instance, the extraction of uranium and the enrichment of uranium are extremely energy-intensive processes. Life-cycle analysis of the whole fuel chain clearly shows the contribution of nuclear power to climate change. In a ground-breaking study Sovacool et al screened 103 lifecycle studies of greenhouse gas equivalent emissions for nuclear power plants to identify a subset of the most current, original, and transparent studies. They calculated that while the range of emissions for nuclear energy over the lifetime of a plant reported from qualified studies examined is from 1.4 grams of carbon dioxide equivalent per kWh (gCO2e/kWh) to 288 gCO2e/kWh, the mean value is 66 gCO2e/kWh.