In	  a	  low-­‐carbon	  future,	  	  where	  does	  fusion	  ﬁt	  in?	  
Robert	  Socolow	  Princeton	  University	  Introductory	  Address	  Interna>onal	  Conference	  	  on	  Plasma	  Surface	  Interac>ons	  	  in	  Controlled	  Fusion	  Devices	  Richardson	  Auditorium	  Princeton	  University,	  June	  18,	  2018	  	  Above	  410	  for	  the	  ﬁrst	  >me	  last	  April	  Antarc>c	  CO2	  and	  temperature	  vary	  together	  CO2	  today	  CO2	  absorp>on	  band	  Climate	  science	  R&D	  is	  as	  urgent	  energy	  R&D,	  to	  learn	  how	  quickly	  serious	  trouble	  will	  arrive.	  A	  single	  big	  idea	  We	  are	  confron>ng	  one	  overarching,	  counterintui>ve,	  new	  idea:	  Human	  beings	  are	  able	  to	  change	  the	  planet	  at	  global	  scale.	  	  This	  new	  idea	  is	  unwelcome.	  We	  wish	  we	  lived	  on	  a	  larger	  planet.	  Our	  small	  planet	  O	  GtCO2	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  1600	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  3200	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  4800	  A	  few	  more	  More	  than	  a	  century	  	   AA	  few	  decades	  decades	  3oC	  1oC,	  already	  2oC	  A	  useful	  approxima>on:	  The	  long-­‐term	  average	  temperature	  rise	  on	  the	  Earth’s	  surface	  is	  propor>onal	  to	  the	  cumula>ve	  global	  emissions	  of	  CO2.	  	  2oC	  is	  the	  most	  discussed	  target.	  	  The	  mul>plier	  from	  emissions	  to	  temperature	  rise	  reveals	  that	  our	  planet	  is	  small.	  	  Carbon	  budgets	  O	  GtCO2	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  1600	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  3200	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  4800	  A	  few	  more	  More	  than	  a	  century	  	   AA	  few	  decades	  decades	  3oC	  1oC,	  already	  2oC	  “Hubbert	  peak”	  equivalent	  ≈2oC	  40	  1600	  1940	  Add	  one	  rectangle:	  	  40	  billion	  tCO2/yr*	  40	  yrs	  40	  1600	  2020	  ≈3oC	  1600	   1600	   1600	  2100	  1940	  2020	   2060	  2140	  	  	  	  	  	  If	  we	  were	  not	  confron>ng	  climate	  change,	  the	  era	  of	  fossil	  fuels	  (coal,	  oil,	  and	  gas)	  could	  last	  hundreds	  of	  years.	  	  Four ways to emit 5 ton CO2/year
Activity

Amount producing 5 ton CO2/year emissionsa) Drive

30,000 km/yr, 5 liters/100km (45 mpg)b) Fly30,000 km/yrc) Heat home

Natural gas, average house, average climated) Useelectricity

400 kWh/month if all coal-power (1000 gCO2/kWh)
800 kWh/month, natural-gas-power (500 gCO2/kWh)When	  we	  as	  a	  species	  do	  ordinary	  things	  globally	  with	  the	  technologies	  we	  have,	  we	  harm	  ourselves.*	  	  *Examples	  of	  ordinary	  things:	  eaDng	  hamburgers,	  commuDng	  to	  work,	  building	  with	  concrete,	  going	  skiing.	  Budgets	  demand	  choices	  The	  budget	  concept	  leads	  inexorably	  to	  choices	  about	  which	  fossil	  fuels	  to	  extract	  and	  which	  to	  consider	  “unburnable”:	  When?	  	  	   	  	  Whose?	  	  	   	  	  Used	  where?	  	  For	  what	  purpose?
Which	  fossil	  fuels?	  	  Beber	  op>ons	  someday?	  	  Geopoli>cal	  stability	  	  “Fairness”	  	  Who	  judges?	  	  Those	  with	  the	  highest	  H/C	  ra>o?	  

Judgments	  about	  which	  fossil	  fuels	  are	  “unburnable”	  have	  no	  precedents.	  	  “Stabiliza>on	  wedges”…	  in	  2004	  	  2011	  Kentucky	  Derby,	  AP	  Photo/Mab	  Slocum.	  hbps://www.cbsnews.com/pictures/2011-­‐kentucky-­‐derby/7	  Slide	  pair:	  courtesy	  of	  Greta	  Shum,	  Andlinger	  Center,	  Princeton	  University	  “Stabiliza>on	  wedges”… in	  2018	  	  end-use
efficiency
gas forcoalwind/solar

CCS

H2 forfuel

biological

Nuclearfissionefficientcoal plants
storage!

Melbourne	  Cup,	  The	  Foreign	  Correspondents‘	  Club,	  Hong	  Kong.	  hbps://www.fcchk.org/event/melbourne-­‐cup	  Four	  poten>al	  low-­‐carbon	  replacements	  of	  the	  current	  fossil	  energy	  system	  1.
2.
3.
4.

Stop	  CO2	  from	  reaching	  the	  atmosphere	  Greatly	  expand	  wind	  and	  solar	  (the	  most	  credible	  today)	  Expand	  ﬁssion	  power	  Develop	  fusion	  power	  In	  all	  four	  cases,	  the	  replacements	  will	  require:	  	  • aggressive	  energy	  eﬃciency	  	  • deep	  electriﬁcaDon	  • prolonged	  R&D	  • strong	  policy	  support	  Stop	  CO2	  from	  reaching	  the	  atmosphere	  BP’s	  CCS	  Project	  in	  In	  Salah,	  Algeria	  Natural	  gas	  puriﬁca>on	  by	  CO2	  removal,	  then	  CO2	  pressuriza>on	  for	  nearby	  injec>on	  Amine	  contactor	  towers	  U.S.	  CO2	  pipelines	  already	  in	  place	  hbp://www.nicholas.duke.edu/thegreengrok/co2pipeline,	  from	  CO2	  Pipelines	  and	  EOR	  in	  the	  US	  -­‐	  Regulatory	  Issues	  and	  Opportuni@es,	  Lawrence	  J.	  Wolfe,	  lwolfe@hollandhart.com.	  Slide	  11.	  Greatly	  expand	  wind	  and	  solar	  Oﬀ	  the	  Atlan>c	  shore	  Princeton	  Seasonal	  baseload	  power	  to	  complement	  renewables:	  an	  opportunity	  for	  fusion.	  

Alexander	  Bubler,	  Felix	  Dinkel,	  Simon	  Franz,	  Hartmut	  Spliethoﬀ	  ,	  “Variability	  of	  wind	  and	  solar	  power:	  An	  assessment	  of	  the	  current	  situa>on	  in	  the	  European	  Union	  based	  on	  the	  year	  2014.”	  Energy	  106	  (2016),	  147-­‐161,	  Figure	  4.	  Seasonal	  baseload	  power	  to	  complement	  renewables:	  an	  opportunity	  for	  fusion.	  
Fusion	  Here,	  wind	  and	  solar	  are	  complementary.	  
Compe>>on	  is	  hydropower,	  stored	  chemicals,	  thermal	  ponds.	  

Alexander	  Bubler,	  Felix	  Dinkel,	  Simon	  Franz,	  Hartmut	  Spliethoﬀ	  ,	  “Variability	  of	  wind	  and	  solar	  power:	  An	  assessment	  of	  the	  current	  situa>on	  in	  the	  European	  Union	  based	  on	  the	  year	  2014.”	  Energy	  106	  (2016),	  147-­‐161,	  Figure	  4.	  Expand fission power

Aging	  pressure	  vessel	  Dry-­‐cask	  storage	  Site: Surry station, James River, VA; 1625 MW since 1972-73,. Credit: Dominion.

In	  the	  U.S.	  and	  much	  of	  the	  world,	  nuclear	  ﬁssion	  power	  is	  in	  retreat.	  
Age:	  40.	  

Relicensing?	  

Early	  re>rement?	  

U.S.	  power	  plants	  Nuclear	  power:	  fuel	  cycle	  -­‐X	  -­‐>	  nuclear	  war	  Uranium isotope enrichment and spent-fuel reprocessing torecover plutonium are both routes to nuclear weapons.
The global development of nuclear power must not abetnational nuclear weapons programs. Instead, it must be
based on much strengthened international institutions thatgovern the nuclear power fuel cycle in all countries.

U-­‐235	  Gas-centrifuges for enrichment

Pu-­‐239	  Reprocessing plant, La Hague, FranceWhat	  will	  determine	  fusion’s	  future?	  (1	  of	  2)	  	  1. Open	  ques@ons	  for	  fusion	  technology	  	  a. Can	  the	  divertor	  and	  ﬁrst	  wall	  be	  made	  durable	  enough	  to	  avoid	  large	  replacement	  costs	  [your	  mee@ng	  this	  week]?	  	  b. Where	  will	  the	  tri>um	  come	  from	  for	  the	  ﬁrst	  commercial	  plants?	  	  c. How	  will	  the	  stellarator	  compete	  with	  the	  tokamak?	  
2. Fusion	  in	  balance	  with	  renewable	  energy	  a. Where	  there	  are	  large	  winter-­‐summer	  diﬀerences	  in	  solar	  and	  wind	  resources,	  can	  fusion	  provide	  complementary	  seasonal	  base-­‐load	  energy	  compe>>vely	  (e.g.,	  six	  months	  on,	  six	  months	  oﬀ)	  ?	  What	  will	  determine	  fusion’s	  future?	  (2	  of	  2)	  	  3. Can	  fusion	  power	  be	  governed	  in	  ways	  that	  prohibit	  the	  produc@on	  of	  plutonium	  from	  fusion’s	  abundant	  neutrons?	  	  i. No	  uranium	  at	  fusion-­‐only	  reactors.	  
ii. No	  ﬁssion-­‐fusion	  hybrids.	  
Well-­‐governed	  global	  fusion	  power	  is	  less	  likely	  to	  lead	  to	  nuclear	  war	  than	  global	  ﬁssion	  power.	  The	  Nuclear	  Fusion	  Dis>llate	  The	  fusion	  “dis>llate”	  is	  wriben	  for	  the	  reader	  who	  has	  an	  appe>te	  for	  technological	  argument	  but	  has	  no	  background	  and	  no	  comfort	  even	  with	  algebra.	  It	  treats	  both	  technology	  and	  policy	  and	  seeks	  be	  evenhanded.	  
hbps://acee.princeton.edu/wp-­‐content/uploads/2016/05/ACEE-­‐Fusion-­‐Dis>llate.pdf