Perhaps you should try some spelling variations:
"renewable energy resourcess" » "renewable energy sources", "renewable bioenergy resources", "renewable energies resources", "renewable energy sourcess", "renewable energy sourcesss"
"renewable energy resources" » "renewable energy sources", "renewable energy sourcess"
"renewable energy resource" » "renewable energy sources"
"renewable energy source" » "renewable energy sources"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("renewable energy resourcess") OR ((("renewable energy resource") OR ("renewable energy resources"))))) OR ("renewable energy source")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"renewable energy resourcess\") or (((\"renewable energy resource\") OR (\"renewable energy resources\"))))) or (\"renewable energy source\"))".
• Removing quotes may allow a broader search: (((( renewable energy resourcess ) or ((( renewable energy resource ) OR ( renewable energy resources ))))) or ( renewable energy source )).
• Adding a wildcard symbol may retrieve word variants: (((("renewable energy resourcess") or ((("renewable energy resource") OR ("renewable energy resources"))))) or ("renewable energy source"))*.