Page 272 - Biofuels Refining and Performance

Chapter
9

Fuel Cells

A. K. Sinha

9.1 Introduction

Global primary energy consumption (i.e., energy used for space heating,
transportation, generating electricity, etc.) is expected to triple from about
400 exajoules (EJ 10 18 joules) per year in 2000 to about 1200 EJ/yr
in 2050 at the present rate of increase in consumption. However, due to
increased energy efficiency of the devices, the actual increase is expected
to be about 800–1000 EJ.
More than 80% of the present primary energy requirements are met
by fossil fuels. The consequences of burning hydrocarbons at such a
large scale for our energy needs are already evident in the form of global
warming and its disastrous environmental effects. In order to permit sta-
bilization of anthropogenic greenhouse gases, fossil fuel consumption
will have to be limited to about 300 EJ/yr by 2050. Hopefully, the con-
cern about global warming, limit on fossil fuel supplies, and rise in their
prices will force us to gradually decrease the use of fossil fuels in the
future. Reducing hydrocarbon consumption to 300 EJ requires carbon-
free energy sources to supply the difference ~700 EJ/yr. This shortfall
is a problem that requires immediate attention and proactive action for
sustainable development.
The need for an efficient, nonpolluting energy source for transportation,
large-scale generation, and portable devices has spurred the develop-
ment of alternative energy sources. Fuel cells are a promising alternative
energy source that fits the above requirements [1–6]. A fuel cell is an
electrochemical device that converts the chemical energy of a fuel (hydro-
gen, natural gas, methanol, gasoline, etc.) and an oxidant (air or oxygen)
into electricity, with water and heat as by-products. Since no combustion

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