CREATE TABLE table_236 ("Power Source" TEXT, "Number of Generators" FLOAT, "Power Capacity  ( GW ) " TEXT, "% of total Capacity" TEXT, "Capacity factor" TEXT, "Annual Energy  ( billion kWh ) " TEXT, "% of annual production" TEXT)

What is the power capacity when the generators were 781?
SELECT "Power Capacity (GW)" FROM table_236 WHERE "Number of Generators" = '781'
SELECT "Power Capacity (GW)" FROM "table_236" WHERE "Number of Generators" = '781'