The case for coal gasification
Kevin Rhodes, PE, Manager, Energy Utilities Group, Woolpert Inc.
Owners of industrial-scale district
energy heating plants, including
academic institutions, are caught
between the proverbial rock and a hard
place. Within the past few years, natural
gas prices have soared, while regulatory
pressure has increased on owners with
solid fuel-burning boilers – specifically in
the form of the ‘MACT hammer,’ the
maximum achievable control technology
standards in Section 112(j) of the U.S.
Clean Air Act, which takes effect in
So what is the best fuel source for a
college or university with either an existing central heating plant or plans to build
a new one? There are many alternatives
to consider, including biomass, methane,
wastewater treatment plant digest gas
and coal gasification. A mature technology
with applicability on the industrial scale,
coal gasification can be implemented at
the same initial cost as natural gas and
at lower operating costs – without the
regulatory issues associated with burning
Determining coal gasification’s economic viability for a particular owner
involves exploring a number of factors,
including the owner’s load profile, the
availability of relatively high-sulfur coal
and the cost of electricity. This is achieved
by completing a feasibility analysis.
Coal Gas Production
To produce synthetic gas from coal,
the raw coal is fed to the gasifier either
in dry form or slurry. It reacts with
steam and air or oxygen at high temperature and pressure, yielding a synthetic
gas composed primarily of hydrogen
and carbon monoxide and smaller quan-
tities of carbon dioxide and methane.
The gasifier also converts the inorganic
materials in the coal into a vitrified
material, which can be sold in the construction market. The gas can be used to
fire a boiler or as a fuel in an integrated
gasification combined-cycle (IGCC)
power generation configuration.
Figure 1. Strategies for the ‘Take-or-Pay’ Scenario. The ideal operating strategy in a ‘take-or-pay’ scenario is to operate at steady-state at the capacity of the gasification plant. This is rarely possible. The
steam or gas demand must be manipulated to approximate the ideal condition, either by adding non-heating loads in the summer 'trough' or base loading.
Strategies for "Take or Pay" Scenario
Meet Peak with
Utilize Coal Gas
For Other Than
Peak Steam Demand (KPPH)
"Hedge" or Baseload
Peak Gasification Load
Coal Gas for Other Than Heat
Natural Gas Peak
Source: Woolpert Inc.