[1] UCL, Dept Chem Engn, Ctr Proc Syst Engn, London WC1E 7JE, England
[2] Univ London Imperial Coll Sci Technol & Med, Ctr Proc Syst Engn, Dept Chem Engn, London SW7 2AZ, England
[3] Univ London Imperial Coll Sci Technol & Med, Ctr Environm Policy, London SW7 2AZ, England