A nuclear-wind energy system for the USA Russ Cage Presented 3 May 2009 Penguicon (Romulus, MI) Released under the Creative Commons license What are the issues Energy supplies Transport system National security Energy supplies Oil is depleting Coal is heavily polluting Conventional gas declining (in USA) All fossil fuels emit CO2 (Short term looks okay. Long term?) World oil production: falling off a cliff Image credit: Also national security issues Reliance on oil means vulnerability Potential for blackmail Oil states already practicing resource nationalism, withdrawing from free markets Credit crunch means fewer resources financed, lower future capacity. Lower capacity means higher prices unless demand restrained. Where can we get energy? Pretty much everything we can get ultimately comes from the strong nuclear force. 1.Fission: liberating binding energy of uranium. 2.Fusion: turning hydrogen into atoms with greater binding energy. 3.Wind, solar: indirect use of solar fusion energy 4.Fossil fuels: indirect and time-delayed solar energy, but concentrated and convenient Running out of usable fossil fuels, so where next? Where can't we get energy? Some sources are not viable going forward. 1.Fusion: 20 years away from commercial viability... for the last 50 years. 2.Fossil fuels: depleting, polluting and a disaster for the climate*. We are left with solar/wind and fission. *Climate change is controversial. That today's atmospheric CO2 levels are unprecedented in the last several glacial cycles covering the previous ~1 million years is a fact. So is the acidification of the oceans; oceanic pH has gone from 8.2 to 7.75. How about the wind Enormous potential for wind. Wind can supply several times as much energy as US electric grid handles. THE TOP TWENTY STATES for Wind Energy Potential as measured by annual energy potential in the billions of kWh, factoring in environmental and land use exclusions for wind class of 3 and higher. B kWh/Yr B kWh/Yr 1. North Dakota 1, Colorado Texas 1, New Mexico Kansas 1, Idaho South Dakota 1, Michigan Montana 1, New York Nebraska Illinois Wyoming California Oklahoma Wisconsin Minnesota Maine Iowa Missouri 52 Source: An Assessment of the Available Windy Land Area and Wind Energy Potential in the Contiguous United States, Pacific Northwest Laboratory, August PNL-7789 (Total US electric generation is ~4000 billion kWh/year ) That's all well and good, but... How do you use electricity to substitute for oil? Move freight off roads to rails. Rail uses 1/3 as much fuel per ton-mile as semi-trucks. Electric rail uses zero. Electrify local delivery trucks (e.g. Smith Newton) New forms of transport. Image credit: faculty.uwashington.edu Image credit: The devil is in the details Wind can supply energy, but it blows when it wants to. How does it meet demand? Cannot overbuild to meet peak demand directly; cost-prohibitive and wasteful. Current system uses peaking generators Image credit: world-nuclear.org That's the old way If peaking fuel is unavailable or ruled out by emissions, then what? Maybe the answer is... hot air? Compressed Air Energy Storage (CAES) plant planned for Iowa will: Output 1.33 kWh for each kWh input Burn 1.25 kWh natural gas for each kWh output (80% gas-to-electric efficiency, compared to 46% for best simple-cycle gas turbines) Overall efficiency ~50%. Image credit: newenergynews.blogspot.com It's those details again CAES may achieve 80% fuel-to-electric efficiency, but it still burns natural gas. What can we use instead? How about... nuclear? Image credit: David LeBlanc Compressed air in Exhaust What can this do? Making some assumptions: For transport, attempt to replace most diesel fuel (~27 billion gallons/year), all gasoline (~140 billion gallons year). Diesel efficiency assumed to be 40%, gasoline efficiency 20%. For stationary uses, replace all residential and commercial natural gas consumption with heat pumps for heat and hot water. Heat pump CoP assumed to be 4.0 (EER of 13.6). Eliminate all fossil fuel for electric generation. Assumptions, cot'd 2/3 of road freight is diverted to rail, and rail is 100% electrified. 75% of remaining road freight fuel is replaced by batteries. That other capacity... what is it? Obvious candidate: thorium Net generation demand of ~3000 billion kWh/year at year 30 Average production of 342 GW at year 30 Could we build that much? Meeting 342 GW target would require 684 units of 500 MWe average power. Construction rate would be ~23 units/year or ~2/month. Remember LeBlanc's design... Modified Geometry 2 Fluid Reactor* Tube-Within-Shell *Patent Pending Expands power producing volume while maintaining the small inner core needed for a simple 2 Fluid design Features of design Tube assemblies are simple. Building 2/month is a relatively small manufacturing effort. Core salt tubes fit on flatbed trucks. Can be factory-built and inspected; no on-site fabrication of core components required. Factory fabrication of major components allows rapid construction of powerplants. What about pesky details? Peaking power is manageable. 342 GWe at 48% thermal efficiency using supercritical CO2 turbines requires 712 GW heat. 712 GW heat at 80% CAES efficiency yields 570 GW electric in peaking mode. Hydro and other schedulable resources will still be there. Could we build them? Assuming inch walls (1.27 cm) and 6 meter length using Hastelloy-N, each reactor requires ~5 tons Ni (lesser amounts Cr+Mo). This comes to 120 tons/year 120 tons/year is trivial fraction of ~1.5 million tons world production. Could we start them? Assuming 1500 kg starting fissile inventory per GWe, starting 12 GW/year needs 18 tons. USA has upwards of 47,000 tons of spent LWR fuel in storage. This assays at ~0.8% Pu. If 90% can be recovered, ~340 tons of Pu will suffice to start first 19 years of production. Remaining 11 years of 30-year production run can be started with next 19 years of Pu from spent LWR fuel plus bred U-233 or enriched U- 235 if required. Could we fuel them? Th-U cycle requires ~0.8 ton Th per Gwe-year. 342 GW average would need ~270 tons/year. Where could we find this? How about in the trash? USA buried ~3200 tons thorium nitrate in Nevada as useless. That's 12 years of fuel after the 30-year build-out. Dig it up again. Image credit: thoriumenergy.blogspot.com If nuclear's so good... why use wind? Different strengths. Wind can be added on very short notice. Wind farms can go from site selection to completion in 18 months. Nuclear requires longer planning cycle. Unlikely that planning, permits, construction can be done in less than 5 years even with factory construction and expedited procedures. Extensive use of CAES allows wind to supply total energy requirements while nuclear reheat addresses peak demand. Conclusions There is no problem in principle with the replacement of transport fuel with electricity. There is no problem in principle with replacement of fossil fuels in stationary applications with electricity either. There appears to be no substantive barrier to generation of most electric requirements with nuclear+wind. Technologies for doing this have been allowed to molder on the shelf, and a decade+ of fuel was simply thrown away. Mostly we need to stop wasting it!