x Energy 20 2016 10 author energy 2016 01 viewde author energy 2016 02 viewde author energy 2016 03 viewde author energy 2016 04 viewde author energy 2016 05 viewde author energy 2016 06 viewde author energy 2016 07 viewde author energy 2016 08 viewde author energy 2016 09 viewde author energy 2016 10 viewde author energy 2016 11 viewde author energy 2016 12 viewde author energy 2016 13 viewde