We currently have a good number of journals in the field of energy. The journals from Elsevier, Springer journals, the Journal of Renewable and Sustainable Energy and the Energy and Environment Science are great, but in fact have a relatively long processing.
Journals with open access publishing, with payment of publication costs, tend to be faster and there are already some good journals available. Some examples: Energy and Power Engineering and Computational Water, Energy and Environment Engineering of SCIRP, Journal of Energy and Internatinal Journal of Photoenergy of Hindawi, among others.
As a last comment, the International Journal of Energy and Environment has reasonable quality and very short processing time.