Carbon-neutral fuel the carbon dioxide in flue gas emissions from power plants would eliminate their greenhouse gas emissions, although burning the fuel in vehicles would release that carbon because there is no economical way to capture those emissions. This approach would reduce net carbon dioxide emission by about 50% if it were used on all fossil fuel power plants. Most coal and natural gas power plants have been predicted to be economically retrofittable with carbon dioxide scrubbers for carbon capture to recycle flue exhaust or for carbon sequestration. Such recycling is expected to not only cost less than the excess economic impacts
Evolutionary history of plants also formed shallow rooting systems during the Famennian. The rhizophores of the lycopods provide a slightly different approach to rooting. They were equivalent to stems, with organs equivalent to leaves performing the role of rootlets. A similar construction is observed in the extant lycopod "Isoetes", and this appears to be evidence that roots evolved independently at least twice, in the lycophytes and other plants, a proposition supported by studies showing that roots are initiated and their growth promoted by different mechanisms in lycophytes and euphyllophytes. A vascular system is indispensable to rooted plants, as non-photosynthesising roots need a supply of