Environmental Engineering Reference
In-Depth Information
Renewables
u
.
Introduction
Discussion of renewable sources of energy is where you
will
find the largest collection of half-truths and exag-
gerations. The Renewables covered in this chapter
include wind-, solar-, geothermal-, hydro-, ocean-, and
biomass-energy systems (biofuels are treated in the
next
'
s Key World Energy Stat-
istics for
%
of world total primary energy supply (TPES) as they did
in
[
], the renewables make up about
cant contri-
bution to emission-free energy today are large-scale
hydroelectric dams and biomass. Large hydropower
systems supply
, but the only two that make a signi
% of world electricity and
%of
TPES, but are often not included in the de
nition of
renewables for reasons that involve value judgments that
have nothing to do with greenhouse gases and global
warming. Biomass, which contributes
%ofTPES,is
the use of waste plant and forest materials for energy
and is the fuel that the poorest people have available for
heat and cooking as well as supplemental fuel for energy
in more developed nations; I will come back to it brie
y
in the chapter on biofuels.
When large hydro and biomass are excluded, only a
tiny part of TPES comes from wind, solar electrical,
geothermal, ocean, and biofuel systems: about
% in the
