If your assumptions and math are correct (and I have no reason to think otherwise, based on a first reading), then how does the 5X greater land requirement of renewables vs. nuclear power prove that "Renewable energy can generate all the world's energy needs" is a "myth"?Lou had a point, but a point which I believed could be answered. I responded:
Lou, there are several issues here. First, in order build an energy gathering array over a large area, large materials and labor inputs are required. These inputs are expensive, and the massive deployment required will create a materials inflation. Peter Lang and Barry Brook have documented the materials input of renewables, and some of that documentation has appeared on the Energy Collective. There estimates show that nuclear power requires significantly less materials input per unit of generation capacity, and far less materials input per unit of electrical output. You have not disagreed with their estimation of materials input, or of overall expenses, as I recall.
Secondly, the land use requirements of renewables conflicts with other "green" values. Windmills kill birds and bats, soil disturbances required to build solar and wind arrays lead to soil erosion, and at least solar thermal requires large amounts of water, the equivalent amount of water required by a nuclear generating plant, in water scarce areas. In addition to the effect of windmills on flying animals, both solar and wind have other intrusions into wildlife habitat. Solar thermal has an especially egregious effect on both soil and habitat, because it requires scraping soil bare of all vegetation. In addition, renewables arrays are visually intrusive, and deface the landscape, Windmills also create noise pollution. The manufacture of PV modules is both energy intensive and creates large amounts of toxic waste. Since much of that manufacture has moved or is moving to China, the management of that waste is not under effective control.
Thirdly, the materials, labor and capital costs of a renewables solution are would all be extremely high, and many renewables advocates have expressed doubts that the massive deployment of renewables energy sources is possible by 2050. In fact, many renewables advocates see an energy gap that would require bridging by fossil fuel use to 2050 and quite probably beyond. Most hide the implication of this by limiting the fossil fuel use to natural gas, which is, of course, not green at all.
Fourth, renewables advocates acknowledge that renewables cannot fulfill current energy demands, but argue that demand can be dramatically lowered through investments in efficiency. Although current efficiency efforts are proving successful, there are potential structural impediments that may impede efficiency efforts down the road. In addition, successful efficiency efforts would also lower the cost of a nuclear substitute for fossil fuel generation.
Fifth, in order to be successful, an all renewable grid would require a huge and costly expansion of its electrical gathering and distribution system, and a large investment in energy storage systems. Nuclear would require far fewer modifications to the present grid, and energy storage with nuclear would be limited to cases in which it was clearly cost effective.
Sixthly nuclear has the potential for producing industrial process heat and cogeneration, while renewables do not. Waste heat and electricity from sea side nuclear plants can be used to desalinate sea water. Renewables are far more limited in their capacity to produce fresh water.
Lastly, and this is a very important point. The potential exists to dramatically increase the land use and materials input efficiency of nuclear power, by switching to a more advanced type of reactor. Labor costs can be dramatically lowered by changing nuclear manufacturing techniques. The means that nuclear capital costs can be dramatically lowered in a way that is not possible with renewables.