Index: data/helpdata.txt
===================================================================
RCS file: /home/freeciv/CVS/freeciv/data/helpdata.txt,v
retrieving revision 1.70
diff -u -r1.70 helpdata.txt
--- helpdata.txt	1999/07/05 20:17:00	1.70
+++ helpdata.txt	1999/07/20 08:39:10
@@ -823,7 +823,12 @@
 %% Allows a city to grow beyond size 12.
 ---
 # Solar Plant
-This improvement has not been implemented.
+Eliminates pollution generated from production in a city.  It also
+increases the shield production of a Factory or Mfg. Plant in the
+city. Together with a Hydro/Power/Nuclear plant this means a 200%
+production bonus.
+A solar plant even helps fighting global warming by absorbing some
+of the heat radiated from the sun.
 ---
 # Space Component
 Space Components can be differentiated into Propulsion and Fuel
Index: data/default/buildings.ruleset
===================================================================
RCS file: /home/freeciv/CVS/freeciv/data/default/buildings.ruleset,v
retrieving revision 1.3
diff -u -r1.3 buildings.ruleset
--- buildings.ruleset	1999/05/14 19:57:23	1.3
+++ buildings.ruleset	1999/07/20 08:39:26
@@ -61,8 +61,8 @@
 "SDI Defense",        0, "Laser",              200, 4,  0, "None"
 "Sewer System",       0, "Sanitation",         120, 2,  0, "None"
 
-;"Solar Plant",       0, "Environmentalism",   320, 4,  0, "None"
-"Solar Plant",       0, "Never",              320, 4,  0, "None"
+"Solar Plant",       0, "Environmentalism",   320, 4,  0, "None"
+;"Solar Plant",       0, "Never",              320, 4,  0, "None"
 
 "Space Component",   0, "Plastics",           160, 0,  0, "None"
 "Space Module",      0, "Superconductors",    320, 0,  0, "None"
Index: data/default/techs.ruleset
===================================================================
RCS file: /home/freeciv/CVS/freeciv/data/default/techs.ruleset,v
retrieving revision 1.1
diff -u -r1.1 techs.ruleset
--- techs.ruleset	1999/01/30 02:57:55	1.1
+++ techs.ruleset	1999/07/20 08:39:27
@@ -49,8 +49,8 @@
 "Electricity",           "Metallurgy",          "Magnetism"
 "Electronics",           "The Corporation",     "Electricity"
 "Engineering",           "The Wheel",           "Construction"
-"Environmentalism",      "Never",               "Never"
-; "Environmentalism",      "Recycling",           "Space Flight"
+; "Environmentalism",      "Never",               "Never"
+"Environmentalism",      "Recycling",           "Space Flight"
 "Espionage",             "Communism",           "Democracy"
 "Explosives",            "Gunpowder",           "Chemistry"
 "Feudalism",             "Warrior Code",        "Monarchy"
Index: server/citytools.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/server/citytools.c,v
retrieving revision 1.46
diff -u -r1.46 citytools.c
--- citytools.c	1999/07/14 11:07:03	1.46
+++ citytools.c	1999/07/20 08:39:58
@@ -400,6 +400,10 @@
     
     if (can_build_improvement(pcity, B_POWER))
       values[B_POWER]=pcity->shield_prod*100;
+
+    /* I didn't really know how this worked when I added this */
+    if (can_build_improvement(pcity, B_SOLAR))
+      values[B_SOLAR]=pcity->shield_prod*100+pcity->pollution*125;
   }
 
   if (can_build_improvement(pcity, B_MFG)) 
@@ -473,6 +477,8 @@
 int set_city_shield_bonus(struct city *pcity)
 {
   int tmp = 0;
+  double mul = 1.0;
+  
   if (city_got_building(pcity, B_FACTORY)) {
     if (city_got_building(pcity, B_MFG))
       tmp = 100;
@@ -482,8 +488,10 @@
     if (city_affected_by_wonder(pcity, B_HOOVER) ||
         city_got_building(pcity, B_POWER) ||
         city_got_building(pcity, B_HYDRO) ||
-        city_got_building(pcity,B_NUCLEAR))
-      tmp *= 1.5;
+        city_got_building(pcity,B_NUCLEAR)) mul += 0.5;
+    if (city_got_building(pcity, B_SOLAR)) mul += 0.5;
+
+    tmp *= mul;
   }
 
   pcity->shield_bonus = tmp + 100;
Index: server/cityturn.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/server/cityturn.c,v
retrieving revision 1.63
diff -u -r1.63 cityturn.c
--- cityturn.c	1999/07/14 11:07:03	1.63
+++ cityturn.c	1999/07/20 08:39:58
@@ -312,12 +312,16 @@
   int poppul=0;
   struct player *pplayer=&game.players[pcity->owner];
   pcity->pollution=pcity->shield_prod;
-  if (city_got_building(pcity, B_RECYCLING))
-    pcity->pollution/=3;
-  else  if (city_got_building(pcity, B_HYDRO) ||
-	   city_affected_by_wonder(pcity, B_HOOVER) ||
-	    city_got_building(pcity, B_NUCLEAR))
-    pcity->pollution/=2;
+  if (city_got_building(pcity, B_SOLAR))
+    pcity->pollution=0;
+  else {
+    if (city_got_building(pcity, B_RECYCLING))
+      pcity->pollution/=3;
+    if (city_got_building(pcity, B_HYDRO) ||
+        city_affected_by_wonder(pcity, B_HOOVER) ||
+        city_got_building(pcity, B_NUCLEAR))
+      pcity->pollution/=2;
+  }
   
   if (!city_got_building(pcity, B_MASS)) {
     if (get_invention(pplayer, A_INDUSTRIALIZATION)==TECH_KNOWN)  mod=1;
Index: server/civserver.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/server/civserver.c,v
retrieving revision 1.102
diff -u -r1.102 civserver.c
--- civserver.c	1999/07/14 11:23:15	1.102
+++ civserver.c	1999/07/20 08:39:59
@@ -762,15 +762,22 @@
 **************************************************************************/
 static void update_pollution(void)
 {
-  int x,y,count=0;
+  int i,x,y,count=0,solar_plants=0;
   
   for (x=0;x<map.xsize;x++) 
     for (y=0;y<map.ysize;y++) 
       if (map_get_special(x,y)&S_POLLUTION) {
 	count++;
       }
-  game.heating=count;
-  game.globalwarming+=count;
+  /* count solar plants */
+  for (i=0;i<game.nplayers;i++) {
+    city_list_iterate(game.players[i].cities, pcity)
+      if (city_got_building( pcity, B_SOLAR )) solar_plants++;
+    city_list_iterate_end;
+  }
+
+  game.heating = count - solar_plants;
+  game.globalwarming = MAX( 0, game.globalwarming + game.heating);
   if (game.globalwarming<game.warminglevel) 
     game.globalwarming=0;
   else {