﻿SOLAR 
  RADIATION 
  AS 
  A 
  POWER 
  SOURCE 
  — 
  ABBOT 
  107 
  

  

  to 
  suppose 
  that 
  units 
  of 
  more 
  than 
  5 
  horsepower 
  (area 
  of 
  mirror 
  

   projection 
  12y 
  2 
  by 
  20 
  feet) 
  would 
  be 
  found 
  desirable. 
  

  

  Such 
  units 
  could 
  be 
  assembled 
  in 
  groups 
  of 
  30. 
  occupying 
  a 
  ground 
  

   area 
  150 
  feet, 
  east-west, 
  by 
  250 
  feet, 
  north-south, 
  without 
  undue 
  

   mutual 
  shading, 
  so 
  as 
  to 
  give 
  a 
  maximum 
  of 
  150 
  horsepower 
  per 
  

   group. 
  Such 
  a 
  group 
  of 
  machines 
  could 
  be 
  mechanically 
  operated 
  

   in 
  common 
  as 
  regards 
  rotation 
  of 
  mirrors 
  and 
  pumping 
  of 
  feed 
  water. 
  

   They 
  could 
  also 
  deliver 
  steam 
  to 
  a 
  common 
  superheater 
  for 
  use. 
  

  

  It 
  is 
  estimated 
  that 
  the 
  United 
  States 
  uses 
  the 
  equivalent 
  of 
  ap- 
  

   proximately 
  10 
  trillion 
  horsepower 
  hours 
  of 
  power 
  annually 
  for 
  light, 
  

   heat, 
  transportation, 
  and 
  manufacturing. 
  Assuming, 
  as 
  above, 
  

   37,500 
  square 
  feet 
  of 
  space 
  required 
  for 
  150 
  horsepower 
  from 
  the 
  solar 
  

   source, 
  there 
  would 
  be 
  required 
  30,000 
  square 
  miles 
  of 
  territory 
  to 
  

   supply 
  this 
  entire 
  requirement, 
  assuming 
  only 
  8 
  hours' 
  sunshine 
  per 
  

   day 
  of 
  the 
  average 
  solar 
  intensity 
  stated 
  above, 
  namely, 
  1.35 
  calories 
  

   per 
  square 
  centimeter 
  per 
  minute. 
  The 
  State 
  of 
  New 
  Mexico 
  alone 
  

   has 
  approximately 
  four 
  times 
  this 
  area. 
  

  

  COST 
  AND 
  OTHER 
  CONSIDERATIONS 
  

  

  The 
  cost 
  of 
  solar 
  power 
  is 
  difficult 
  to 
  estimate. 
  It 
  depends 
  on 
  the 
  

   quantity 
  used. 
  With 
  large 
  installations, 
  care 
  and 
  upkeep 
  would 
  

   become 
  nearly 
  negligible, 
  so 
  that, 
  with 
  a 
  10-percent 
  return 
  on 
  invest- 
  

   ment, 
  the 
  cost 
  of 
  power 
  at 
  the 
  plant 
  might 
  be 
  estimated 
  as 
  less 
  than 
  

   one-third 
  cent 
  per 
  horsepower-hour. 
  

  

  There 
  remains 
  to 
  consider 
  the 
  serious 
  drawback 
  that 
  direct 
  solar 
  

   power 
  is 
  unavailable 
  at 
  night. 
  For 
  certain 
  purposes, 
  as 
  irrigation, 
  

   this 
  is 
  not 
  a 
  serious 
  objection. 
  

  

  However, 
  since 
  writing 
  the 
  above 
  I 
  have 
  thought 
  that 
  the 
  means 
  

   shown 
  in 
  United 
  States 
  Patent 
  No. 
  2,247,830, 
  of 
  July 
  1, 
  1940, 
  could 
  

   be 
  expanded 
  to 
  include 
  a 
  strong 
  insulated 
  reservoir 
  of 
  water. 
  Solar 
  

   heating 
  would 
  be 
  conveyed 
  to 
  the 
  water, 
  by 
  gravity 
  circulation 
  

   through 
  a 
  coil 
  immersed 
  therein, 
  from 
  a 
  black 
  high-boiling 
  liquid 
  

   filling 
  a 
  vacuum-sheathed 
  glass 
  focus 
  tube. 
  In 
  this 
  way 
  all 
  the 
  ex- 
  

   pense 
  of 
  the 
  flash 
  boiler 
  would 
  be 
  eliminated, 
  all 
  moments 
  of 
  solar 
  

   heating 
  would 
  be 
  utilized, 
  the 
  water 
  in 
  the 
  reservoir 
  would 
  be 
  main- 
  

   tained 
  in 
  a 
  superheated 
  state 
  night 
  and 
  day, 
  and 
  superheated 
  steam 
  

   would 
  issue 
  to 
  the 
  engine 
  on 
  opening 
  a 
  cock. 
  

  

  