Word: terawatt-year Part of Speech: noun Etymology: By surface analysis, terawatt + year, or, by surface analysis, tera- + watt-year. 1. A unit of energy equal to that provided by one terawatt of power acting for one year (31·536 × 10¹⁸ joules). Example: Meronyms: (sorted by magnitude) yoctojoule (1.000e-24 J) < zeptojoule (1.000e-21 J) < attojoule (1.000e-18 J) < hartree (4.35974e-18 J) < femtojoule (1.000e-15 J) < picojoule (1.000e-12 J) < nanojoule (1.000e-9 J) < microjoule (1.000e-6 J) < millijoule (1.000e-3 J) < joule (1 J) < milliwatt-hour (3.6 J) < gram calorie (4.184 J) < microwatt-year (31.536 J) < kilojoule (1.000e3 J) < British thermal unit (1.05506e3 J) < watt-hour (3.600e3 J) < kilogram calorie (4.184e3 J) < milliwatt-year (31.536e3 J) < megajoule (1.000e6 J) < kilowatt-hour (3.600e6 J) < watt-year (31.536e6 J) < gigajoule (1.000e9 J) < megawatt-hour (3.600e9 J) < kilowatt-year (31.536e9 J) < terajoule (1.000e12 J) < gigawatt-hour (3.600e12 J) < megawatt-year (31.536e12 J) < petajoule (1.000e15 J) < terawatt-hour (3.600e15 J) < gigawatt-year (31.536e15 J) < exajoule (1.000e18 J) < petawatt-hour (3.600e18 J) Example: Energy conservation can bring you 1 terawatt and it falls in line with the soft options, but not dozens of terawatts. So what do you do then when dozens of terawatts are at stake? Fortunately there is more than one option to provide, but they all have their problems. (Figure 7.) Coal is half an option, because 7,000 billion tons or 7,000 terawatt years is the geologically existing amount of coal. More pragmatically and realistically you have a thousand terawatt years of coal. But if you do it, you have land requirements, you have the problem of working conditions, safety, CO₂, and other pollutants. Another option is the fast breeder reactor, or nuclear power based on the fast breeder. This could provide 200 million terawatt years. Solar essentially is infinite, fusion is essentially the same thing as the fast breeder, contrary to the widespread belief. It is the same ball game, probably under better conditions, but qualitatively the same thing, that is[,] several hundred million terawatt years. Geothermal is not so clear. It is definitely larger than coal but [it's] not in the hundreds of millions of terawatt years or like solar. That means we do have principally speaking a number of options for the essentially unlimited supply of energy; coal, solar, and nuclear being the most prominent ones. Now, if that is the case, we have to master a transition. We have to go from the present equilibrium between cheap resources ($2.00 per barrel at production costs or even less) and demands, to one of these options or, better, combinations of these options. That is the transition for 50 years. What the energy project is about is to identify the transit strategies to do it. Contrary to the past, optimization is not the name of the game. Instead, feasibility of the transition is the name of the game—and feasibility is characterized by constraints. So we are strongly studying the constraints, specifically: man's impact on climate by Dr. Williams who is here among us, risk and risk perception by society drawing on the IAEA [International Atomic Energy Agency] (that means almost a sociological project), market penetrations, and capital cost requirements. These are the four predominant constraints selecting the feasible strategies for that transition for which we have 50 years to come.