diff --git a/app/models/generator_type.rb b/app/models/generator_type.rb
index a2c2443..c836c67 100644
--- a/app/models/generator_type.rb
+++ b/app/models/generator_type.rb
@@ -28,6 +28,10 @@ def renewable?
   end
 
   def marginal_cost game, operating_level=100
+    marginal_fuel_cost(game, operating_level)
+  end
+
+  def marginal_fuel_cost game, operating_level=100
     marginal_fuel(operating_level) * game.current_price(fuel_type.market)
   end