00100	\\M0BDR25;\M1BDI25;\M2XMAS25;\F0
00200	Is it feasible to make hydrocarbons from atmospheric carbon dioxide
00300	and water at an interesting cost?
00400	Is there a good way of using hydrogen as a vehicle fuel?
00500	
00600	
00700	\C\F2DRAFT
00800	
00900	
01000	\F0\CSOME QUESTIONS ABOUT THE ENERGY PROBLEM
01100	
01200	
01300	\J	The population  the earth  can support  at a  given level  of
01400	technology  is limited.   Some people  think that this  limitation is
01500	imposed by energy  considerations.   Some of them
01600	even  think that the  present population  is larger
01700	than  energy considerations  will permit sustaining  for thousands of
01800	years.  M.  King Hubbert  (196x),  for  example,  suggests  that  the
01900	population be reduced  to about half its present  value and that this
02000	might be sustainable.   Others propose  different numbers.   However,
02100	these estimates don't seem  to have any definite basis.   If you rely
02200	entirely on  present sources of energy  the sustainable population is
02300	very much smaller, and  if you believe  that nuclear and solar  energy
02400	are available, then even larger  populations than the present one can
02500	be  sustained.   To  put  it bluntly,    these estimates  seem  to be
02600	ideological compromises based partly  on the authors' sense  that the
02700	world is crowded and partly on the desire not to seem implausible.
02800	
02900		In  my opinion, while  energy certainly  does put a  limit on
03000	the population the planet  can sustain, this limit  is so large  that
03100	other factors will limit it first.  In  particular, I would hope that
03200	mankind will limit  its population on earth just to avoid crowdedness
03300	long before energy or any other physical limitation applies.
03400	
03500		If it can be firmly established that energy is not  likely to
03600	limit be  the operative  limitation on population,   then  the energy
03700	problem  and   the  population  problem  can  be  decoupled.    Those
03800	interested in the  population problem can  try to establish what  the
03900	population  problems of the  different regions  of the world  are, and
04000	what combinations  of  esthetic and  resource  considerations  should
04100	limit population and,  what measures have  to be taken at  what times.
04200	Those  interested in the  energy problem  can plan the  transition to
04300	new sources of  energy adequate to  supply any plausible  population.
04400	The only people who will be  seriously discommoded are those who find
04500	their   real  reasons  for  wanting  population  limitation  measures
04600	insufficiently convincing, and therefore want  to buttress them  with
04700	energy considerations without too much concern with their validity.
04800	
04900		I believe the following can be established:
05000	
05100		1.   Nuclear fission  using the  breeder reactor  can provide
05200	energy enough to  allow a  population of  ten billion  a standard  of
05300	living twice as  high as the  present American standard for  a period
05400	of  millions of years.   This  can be done  at energy costs  in labor
05500	less than twice what  we now pay.  (Most  likely, the cost of  energy
05600	can continue to go down, perhaps after  a small hiccup).  The risk of
05700	catastrophe  from  radiation  can  be kept  low  enough  so  that the
05800	expected number of deaths and injuries including genetic  can be kept
05900	at least  an order of magnitude  below what the  automobile now costs
06000	us.
06100	
06200		2. Solar energy can also support such a population at such  a
06300	standard of living, but we  don't yet know how to get  the costs down
06400	to even ten times  what we are now paying.  Since we now put about 3%
06500	of our GNP  into energy,  putting  30% into it  is worth avoiding  if
06600	possible.
06700	
06800		3.   Whether fusion power  plants can  be built is  still not
06900	scientifically decided.  Even less can the costs be predicted.
07000	
07100		4.   We cannot  continue our present  dependence on petroleum
07200	and natural gas for very long.   We have at most thirty years  to get
07300	most of  our energy from other  sources unless we want  to put severe
07400	restraints on economic  expansion. Even  ten years  may be  difficult
07500	without full use of Middle East resources.
07600	
07700		5. The most  obvious way out  of the immediate problem  is to
07800	continue  to develop fission  reactors for  electricity and to  go to
07900	large scale conversion of coal to vehicle fuel.
08000	
08100		6. We should  start developing ways  of using nuclear  energy
08200	to get  vehicle fuel.   A major  possibility is hydrogen  obtained by
08300	decomposing  water  either electrolytically  or  hopefully by  a some
08400	more efficient  process  using heat.    However, the  possibility  of
08500	using  carbon dioxide  from  the air  and  water with  energy to  get
08600	hydrocarbons is also  worth considering, because  the low density  of
08700	hydrogen and  the low temperatures  required for  handling it in  the
08800	liquid form may make it less desirable than hydrocarbons.
08900	
09000		7.   Of the  various other sources  of energy  that have been
09100	proposed, all but  geothermal can now  be shown  to be very  limited.
09200	The likelihood that  geothermal energy can be a major  source is low,
09300	but the possibility still exists and should be explored.
09400	
09500		8.  From a  global point  of view,  the best solution  to the
09600	energy  problem  is  to  use  up  the  planet's  oil  reserves  while
09700	developing an  alternate energy source.  This  is because pumping the
09800	oil from the  known reserves is  quite cheap and  the money saved  by
09900	doing this can  be invested in  development of new sources  and other
10000	good  things.  However,  the price at  which the oil  can actually be
10100	obtained depends on bargaining  considerations that include the  cost
10200	of doing without  Arab oil soon. This assumes  that hydrocarbons used
10300	for chemical purposes can also be made artificially using energy.\.
10400	
10500	\F1\C**Literature citations are to be supplied for the above contentions**\F0
10600	
10700	
10800	\J	All  the  above  considerations  have  a  mainly  qualitative
10900	character.   In order  to  convincingly decouple  the energy  problem
11000	from the  population problem, we need  some quantitative information.
11100	Here are some of the questions that should be answered:
11200	
11300		1. At  what  price  of  natural  gas  does  nuclear  produced
11400	hydrogen  become competitive?    This should  be  answered under  the
11500	assumption  that the hydrogen is  produced electrolytically and under
11600	the assumption that it can be produced thermally.
11700	
11800		2. At what  price of  oil does hydrogen  or nuclear  produced
11900	hydrocarbon become competitive?
12000	
12100		3. Is gas  from coal cheaper than  nuclear produced hydrogen?
12200	Will this  hold true as long as there is a significant amount of coal
12300	available or will hydrogen be cheaper at some time?
12400	
12500		4. Is there a cost advantage in going to  much larger nuclear
12600	plants  if they  are being  used to  produce something  storable like
12700	hydrogen or hydrocarbons?  Present  nuclear power plants are  limited
12800	in size by  the rate of  growth of utilities and  by the need  not to
12900	put  all the electricity supply  eggs in one basket  since all plants
13000	have some down time.
13100	
13200		5. Can  the  present  rate  of production  of  nuclear  power
13300	plants be speeded up?  Are  the companies learning enough to make the
13400	process smoother?
13500	
13600		6.  Is  there  really  going to  be  a  shortage  of enriched
13700	uranium?
13800	
13900		7. At what price of Arab crude oil does it  pay to do without
14000	it? It  is very important to  have a feasible plan  for getting along
14100	without Arab  oil  even  if we  hope  the  oil will  continue  to  be
14200	available. The  cost of such  a plan will  determine a  maximum price
14300	beyond  which they  can eat the  oil.   Hard bargaining based  on the
14400	knowledge of  such a  price  can probably  get a  considerably  lower
14500	price.
14600	
14700		8. At what price of oil does it become profitable to replace
14800	existing oil powered plants by nuclear plants rather than just build
14900	new capacity as nuclear?  Is it feasible to convert existing oil-powered
15000	plants to nuclear by replacing the oil powered steam generator by a
15100	nuclear steam generator?
15200	
15300		9. How do the problems  of the other industrialized countries
15400	differ  from those faced  by the United  States?  It  would seem that
15500	many  other countries  are  worse  off  than the  U.S.  which  should
15600	require them  to take the lead  in developing new  sources of energy.
15700	However, their actual efforts seem to  be less than that of the  U.S.
15800	Can  this be  ascribed  simply to  the  tradition of  U.S.  technical
15900	leadership? Perhaps  they could be persuaded to  pay a large share of
16000	the costs of a joint development program.\.
16100	
16200							John McCarthy
16300							Computer Science Dept.
16400							Stanford University