Economics of nuclear power plants nuclear plants going online in 2019, capital costs will make up 74% of the levelized cost of electricity; higher than the capital percentages for fossil-fuel power plants (63% for coal, 22% for natural gas), and lower than the capital percentages for some other nonfossil-fuel sources (80% for wind, 88% for solar PV). Areva, the French nuclear plant operator, offers that 70% of the cost of a kWh of nuclear electricity is accounted for by the fixed costs from the construction process. Some analysts argue (for example Steve Thomas, Professor of Energy Studies at the University of Greenwich in the UK,
Evolutionary history of plants billion years ago, and that communities of complex, multicellular photosynthesizing organisms existed on land in the late Precambrian, around . Evidence of the emergence of embryophyte land plants first occurs in the mid-Ordovician (~), and by the middle of the Devonian (~), many of the features recognised in land plants today were present, including roots and leaves. Late Devonian (~) free-sporing plants such as "Archaeopteris" had secondary vascular tissue that produced wood and had formed forests of tall trees. Also by late Devonian, "Elkinsia", an early seed fern, had evolved seeds. Evolutionary innovation continued into the Carboniferous and still continues