1. Energy and Environmental Economics, 101 Montgomery Street, Suite 1600, San Francisco, CA 94104, USA.
2. Monterey Institute of International Studies, 460 Pierce Street, Monterey, CA 93940, USA.
3. Energy and Resources Group, University of California, Berkeley, CA 94720, USA.
4. Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.