Page 379 - Handbook of Energy Engineering Calculations

plants do not consume fossil fuel, so they are not depleting the world’s
supply of such fuels. And by using the seemingly unlimited supply of heat
from the earth, such plants are contributing to an environmentally cleaner and
safer world while using a renewable fuel.
Another renewable fuel available naturally that is receiving—like

geothermal power—greater attention today is biomass. The most common
biomass fuels used today are waste products and residue left over from
various industries, including farming, logging, pulp, paper, and lumber

production, and wood-products manufacturing. Wooden and fibrous materials
separated from the municipal waste stream also represent a major source of
biomass.
Although biomass-fueled power plants currently account only for about 1
percent of the installed generating capacity in the United States, or 8000

MW, they play an important role in solving energy and environmental
problems. Since the fuels burned in these facilities are considered waste in
many cases, combustion yields the double benefits of reducing or eliminating

disposal costs for the seller and providing a low-emission fuel source for the
buyer. On a global scale, biomass firing could present even more advantages,
such as: (1) there is no net buildup of atmospheric CO and air emissions are
2
lower compared to many coal- or oil-fired plants. (2) Vast areas of deforested
or degraded lands in tropical and subtropical regions can be converted to
practical use. Because much of the available land is in the developing regions
of Latin America and Africa, the fuels produced on these plantations could

help improve a country’s balance of payments by reducing dependence on
imported oil. (3) Industrialized nations could potentially phase out
agricultural subsidies by encouraging farmers to grow energy crops on idle
land.

The current cost of growing, harvesting, transporting, and processing high-
grade biomass fuels is prohibitive in most areas. However, proponents are
counting on the successful development of advanced biomass-gasification
technologies. They contend that biomass may be a more desirable feedstock

for gasification than coal because it is easier to gasify and has a very low
sulfur content, eliminating the need for expensive O production and sulfur-
2
removal processes.

One report indicates that integrated biomass-gasification–gas-turbine-