CREATE TABLE table_68269 ("Unit" CLOB, "Type" CLOB, "Gross MW" CLOB, "Construction start" CLOB, "Operation start" CLOB)

Operation start of 2015 has what gross mw?
SELECT "Gross MW" FROM table_68269 WHERE "Operation start" = '2015'
SELECT "Gross MW" FROM "table_68269" WHERE "Operation start" = '2015'