Technical Programme - Materials Research Society of Singapore ...

ICMAT 2009 and IUMRS - ICA 2009 Technical Programme
Hartmut MICHEL
Nobel Laureate in Chemistry
Wednesday, 1 July 2009
19:00 – 20:00 hrs
University Cultural Centre,
National University of Singapore
Chair:
Keith CARPENTER
Institute of Chemical and Engineering Sciences,
Singapore
Biofuels - can they help to reduce global warming or to
solve the energy crisis?
It becomes generally accepted that the global warming
which we undoubtedly observe, is the result of an increased
concentration of greenhouse gases like carbon dioxide
and methane in the atmosphere. Within this scenario it is
evident that we have to reduce the emissions of carbon
dioxide in order to stop or to decrease global warming. It
will be necessary to switch from energy mainly based on
fossil energy to renewable energy. One big hope is the use
of biofuels like bioethanol, biodiesel, sundiesel, biogas and
so on. Biofuels are products derived from photosynthesis
of plants. It will be shown that the overall effi ciency of
photosynthesis is very low: less than one percent of the
energy of the sunlight is stored in the form of biomass,
and there is not much hope for a substantial improvement.
Biogas and biodiesel per area unit and year contain about
0.4 % of the energy of the sunlight which the area unit has
received in the same time. In addition at least 50 % of the
energy which is contained in biogas or biodiesel had to
be invested from conventional (fossil) energy sources to
produce the biogas or biodiesel. Therefore, production and
usage of biogas or biodiesel is not carbon dioxide neutral.
By comparison, usage of photovoltaic cells is more
effi cient by a factor of 50 to 100 with respect to energy
conversion, and electric engines are fourfold as effi cient
as combustion engines. Consequently driving a car using
electric batteries, loaded by photovoltaic cells, and electric
engines requires only 0.2 % of the land that would be
required using biofuels and combustion engines. Growing
energy plants therefore is a very ineffi cient way of land
use. The usage of biofuels made of palm oil or soy beans
from tropical countries will enhance the deforestation, lead
to a loss of the tropical rain forest and increase climatic
changes. In addition we shall lose biodiversity and many
biological compounds which might help fi ghting human
diseases.
pg 44
Public Lectures