Page 342 - Sustainability in the Process Industry Integration and Optimization

Co n c l u s i o n s a n d Fu r t h e r I n f o r m a t i o n 319

the waste with other fuels (Werther, 2007). Second, it is important to
prevent the release of toxic pollutants with the flue gas—for example,
the emission of dioxins from incinerated solid wastes. These
emissions can be minimized by proper waste separation and
moisture reduction prior to the incineration (Werther, 2007). Third,
the moisture content poses other challenges besides the formation of
dioxins. The higher the moisture content, the larger fraction of
energy is wasted on evaporating it; thus, increased moisture reduces
the specific energy gain from incineration. This means that, for
purposes of energy generation, waste with especially high water
content is more beneficially treated via other processes. Examples
include the anaerobic digestion of wet organic waste from food
industry and agriculture (Zhang et al., 2007; Macias-Corral et al.,
2008) and the supercritical gasification of black liquor from pulp-
and-paper plants (Pettersson and Harvey, 2009; Sricharoenchaikul,
2009).

14.2.5 Better Utilization of Low-Grade Heat
Desai and Bandyopadhyay (2010) proposed a scheme incorporating
organic Rankine cycles (ORCs) in the efficient utilization of low-
grade waste heat for power generation. They provided a graphically
assisted procedure for integrating an industrial process with an ORC,
thereby reducing the process cooling demand and the need to import
external power.
14.2.6 Energy Planning That Accounts for Carbon Footprint
The international community has become increasingly concerned
with climate change. Most attention has been focused on the carbon
footprint (CFP), which quantifies the impact of greenhouse gas
emissions. In parallel with this development, the issue of energy
independence has been given more attention in a number of countries
that import fossil fuels—especially the United States, European
countries (except Norway), and, to a lesser extent, Australia and
Japan.
An interesting paper by Foo, Tan, and Ng (2008) addresses
“Carbon and Footprint-Constrained Energy Planning Using Cascade
Analysis Technique.” The authors presented algebraic targeting
techniques for energy-sector planning under constraints on CO
2
emissions and land availability. This contribution extends the classic
Pinch Analysis of Linnhoff and Hindmarsh (1983) to identify the
minimum amount of low- or zero-carbon energy sources needed to
meet regional or national energy demands while observing limits on
CO emissions.
2
The concept of Regional Energy Clustering presented by Lam,
Varbanov, and Klemeš (2010) involves the synthesis of regional energy
targeting and supply chains. The methodology seeks to account for