A Process-Step Benchmarking Approach to Energy Use at Industrial
Facilities: Examples from the Iron and Steel and Cement Industries

*Michael Ruth, Lawrence Berkeley National Laboratory*

*Ernst Worrell, Lawrence Berkeley National Laboratory*

*Lynn Price, Lawrence Berkeley National Laboratory*

# ABSTRACT

This paper looks at the use of benchmarking approaches for evaluating
industrial energy use. Benchmarks have been used for comparing
industrial facilities or entire sectors, or for making temporal
comparisons. We outline a 'process-step approach' to benchmarking
energy-intensive industries, which accounts for the process differences
between industrial facilities or sectors. We then illustrate the
approach using the cement and the iron and steel industries, and
construct an example using data from the Brazilian iron and steel
industry.

## Introduction

Benchmarking can be a useful tool for understanding energy consumption
patterns in an industrial sector and for designing policy to improve
energy efficiency. Energy benchmarking for industry is a process in
which the energy performance of an individual plant or an entire sector
of similar plants is compared against a common metric that represents
'standard' or 'optimal' performance. It may also entail comparing the
energy performance of a number of plants against each other.

Because benchmark evaluation tools are used for comparison across a
number of plants or sectors, there are two important characteristics
they should have. First, because they are applied to plants or sectors
of different sizes and outputs, the metric used should be irrespective
of plant size. This is accomplished by using the concept of energy
intensity, which measured energy use *per unit of output*. However,
deciding how to measure units of output is not always clear.[^1] Second,
the tool should be applicable to a wide range of facilities (in order to
increase the robustness of the analysis) and so should be able to
compensate for differences in production at similar facilities.

In designing an evaluation tool that compensates for production
differences, it is necessary to take a look inside the production
processes and account for the various steps used. Each of the examples
we look at in the next section accounts for these steps in a similar
way. In this paper we look at energy benchmarking for cement production
and for iron and steel production, following an approach we call
process-step benchmarking. In this approach, the key process steps are
identified and a benchmark performance is assigned to each step. The
performance of a plant is then compared incorporating information about
how each step is used by the plant. In section 3 the process-step
approach is explained more thoroughly. Sections 4 and 5 describe the
application of the approach to cement and to iron and steel production.
In section 6, we use actual energy performance data from 4 Brazilian
iron and steel facilities to illustrate a benchmarking calculation.

## Existing Industrial Benchmarking Programs

Industrial benchmarking has been used primarily in three contexts. The
first context is to evaluate an entire industrial sector, such as iron
and steel, aluminum, cement, etc. This evaluation is used to answer the
following questions: How well is this sector performing compared to how
it would perform using the best available technologies? How well is it
performing compared to the same sector in other countries? Has the
sector been improving over time? The answers to these questions depend
not just on state-of-the-art performance in the sector, but also the
adoption and diffusion of efficient technology throughout the sector.

The second context for benchmarking is the comparison of individual
plants within a sector. A benchmark-type indicator is calculated for all
the facilities within a sector so that they can be compared on even
terms. This evaluation can answer the following questions: What is the
state-of-the-art performance in this given sector? How does my plant
compare against the state-of-the-art? How does it compare against the
majority of other plants in the sector? In developing benchmarks at the
level of individual plants, the issue of proprietary data becomes
important. Individual companies are very reluctant to disclose
information about their production processes, particularly if it will be
released to their competitors. It is important that the indicators
developed are general enough not to reveal any proprietary information
and that a credible system is established that encourages plants to
trust the process.

A third context for industrial energy benchmarking that has been seen
widely in recent years is for large companies to set themselves energy
efficiency goals by using benchmarks. Companies use this approach to set
targets for reducing energy use by certain percentages over given time
frames. Companies do not need to divulge any proprietary information,
since the benchmarking is done internally.

Below we look at examples of industrial benchmarking within each of
these contexts.

# Netherlands Industrial Sector Benchmarking. The Dutch government has been developing a benchmarking methodology for looking at industrial energy use in the country. Developing benchmarks helps in understanding industrial energy consumption patterns in order to assist in policy design. These benchmarks are used to establish voluntary agreements with industry, in which energy-intensive industries agree to reduce energy consumption to avoid additional regulation. 

The approach has been that Dutch industries should be among the best in
the world. Although the level that qualifies as 'best' is subjective,
the concept is to compare Dutch industrial performance to other
countries. In constructing these comparisons, researchers at Utrecht
University accounted for different manufacturing approaches within the
same industry that influence energy consumption (Phylipsen et al 1998).
These differences, which they called *structural indicators*, were
included in their analysis to create fair comparisons across countries.
Some structural indicators they identified were choice of inputs (iron
ore vs. scrap metal in steel making), variety of outputs (various
quality of paper in papermaking), and import/export of intermediate
products (the import of alumina for aluminum production.)

The industrial sector of any country can be compared against how it
would perform using 'best practice' technology, accounting for the
structural indicators. This ratio of how a country performs compared to
how it *could* be performing can then be compared across countries.

# Solomon Associates Benchmarking of Hydrocarbon Industries. Solomon Associates has offered benchmarking capabilities to hydrocarbon industries (refineries and chemical plants) for the past two decades. Their benchmarking tools cover many areas of production, including energy, which is the largest operating expense at many of these plants. They benchmark energy efficiency using a metric they call the Energy Intensity Index (EII) (Birchfield, 2000). In this approach, standard energy consumption factors are developed for each process unit in the hydrocarbon industry. For each facility, the throughput of materials at each unit is multiplied by the consumption factor, and these values are summed across all units to give a standard energy consumption value for the plant. Actual plant energy use is divided by this value to yield a percentage called the EII.

Solomon promotes its benchmarking tool as a source of information and as
an incentive for process improvements. Their indices can, without
revealing proprietary information, provide information on the
state-of-the-art performance in an industry and tell an individual plant
how it compares to other plants and to its own past performance.
Knowledge that more efficient plants exist in an industry and the drive
for process improvements and cost savings can drive gains in energy
efficiency.

**Company-wide energy benchmarking.** Some of the companies that have
been using benchmarking approaches to set energy efficiency goals
include DuPont, Dow, Royal Dutch Shell, BASF, and Chevron (Sun and
Williamson, 1999). DuPont formed a Corporate Energy Leadership Team to
bring attention to the issue of energy utilization. They set a goal to
reduce energy intensity by 15% over the decade of the 1990's,[^2] and
they defined energy intensity as the energy consumed per unit of
production, BTU/pound (Stewart, 1998).

In setting these targets, companies need to recognize that improvements
in energy intensity come from two sources. One is improvements in energy
efficiency -- such that making the same products requires less energy --
and one is structural changes, or changes in the profile of products
that the company makes. Companies should distinguish between these two
changes when setting targets so that their results are more meaningful.
DuPont does report their energy savings on a global basis, so their
improvements would not be a result of shifting energy-intensive
processes to different countries. It is not clear if they account for
any overall changes in the profile of products they produce.

**The Process-Step Approach to Benchmarking**

One of the major critiques of using a benchmark to evaluate industrial
projects is that there is a rarely a homogenous output to use as the
basis for measuring the intensity of energy use (Lazarus et al, 1999).
In electricity generation, it is common to think of energy intensity in
terms of energy use per kilowatt-hour of electricity generated. There is
basically one output commodity in electricity generation, so this metric
makes sense. For industrial manufacturing, output is generally much more
heterogeneous. Some commodities appear to be fairly homogenous, such as
steel, but a close look shows that steel output includes diverse
products such as ingots, slabs, wire, and sheets, and the processes used
can vary. For example, steel can be made starting with iron ore and
coking coal, or can be made from recycled steel. Each of these
differences translates into different energy requirements.

In the process step approach, the key energy-consuming steps for a
manufacturing process are identified, and a facility is evaluated
according to how well it performed at each of these key steps. If it is
designed well, a process step evaluation tool can be used to compare a
number of different facilities, even if their production methods and
outputs vary.

There are four key steps to setting up the process-step approach:

**Step 1: Understand the Industrial Processes.** The process step
approach begins with an understanding of the production processes used
in an industry. Often, there are a number of pathways that lead to the
production of the one central product -- such as liquid steel in the
steel industry, or clinker in the cement industry. The production of
this product encompasses the most energy-intensive production steps.
There are then more pathways that lead from the central intermediate
product to a number of final products -- such as a wide range of steel
products or various grades of cement. An understanding of the production
pathways and key products is needed to correctly set up a benchmarking
system.

**Step 2: Set the Boundaries of the Analysis.** After the key process
steps are understood, a decision is required about which process steps
are included in the analysis for an industry and which will be outside
the analysis boundary. This decision is somewhat subjective, but is
based on a combination of factors. The most energy-intensive steps
should always be included, and steps with lower energy-intensity can be
excluded, particularly if the data required for accurate evaluation are
difficult to acquire. It is important that all potentially substitutable
steps fall on the same side of the analysis boundary, whether that is
inside or outside of the analysis. Setting up boundaries like this helps
to make sure that all projects are evaluated fairly, and also helps to
limit the data requirements by focusing the analysis as much as
possible. Each of these steps must have some sort of measurable physical
throughput that can be used as the basis of an intensity measure.

### Step 3: Define the Benchmark Energy Categories. Once the process steps that will be used in the analysis have been set, there remains a decision about how to treat the benchmark categories. There are a few factors that are considered at this point. For example, is it necessary to include all of the energy sources in the analysis, or can focusing on the main energy sources help to simplify the analysis while still capturing the important information? Also, special consideration is needed for secondary energy carriers, including electricity and steam, to determine the primary energy savings associated with saving one unit of each of these.

### Step 4: Determine Values for the Benchmarks. The final step is to establish benchmark intensities for each process step. There are two major approaches to determining the benchmark values. The first approach is to compile performance information from existing plants or plants that are under construction and to base the benchmark value on this data. The benchmark might be set as the average performance weighted by output, or it might be set to the top 10 or 25 percent of performance. A more sophisticated approach would be to estimate a trend in the data to look for improving performance that would indicate how future plants would be expected to perform. In practice, existing data are often not complete enough to do a thorough analysis of this sort. In any approach that determines a benchmark from a set of existing plants, there needs to be a decision about which plants are included when making the evaluation. Some parameter might be set, such as all plants built in the past ten years, or the most recent 10 plants built, to define which plants belong in the evaluation set.

The second major approach for determining benchmark values is to use
data that represents 'best practice' performance, which could be derived
from either observations at highly efficient plants or from scholarly
publications that study the industry. This approach is much less data
intensive than basing the benchmark of a set of existing plants, but
these 'best practice' values may not be good indicator of the types of
projects going on in individual countries.

**Process-Step Benchmarking in the Cement Industry**

Cement production is an energy-intensive process in which a combination
of raw materials is chemically altered through intense heat to form a
compound with binding properties. Raw materials, including limestone,
chalk, and clay, are mined or quarried, usually at a site close to the
cement mill. These materials are then ground to a fine powder in the
proper proportions needed for the cement. These can be ground as a dry
mixture or combined with water to form a slurry. The addition of water
at this stage has important implications for the production process and
for the energy demands during production. Production is often
categorized as dry process or wet process. Additionally, equipment can
be added to remove some water from the slurry after grinding; the
process is then called semi-wet or semi-dry.

This mixture of raw materials enters the clinker production stage.
During this stage the mixture is passed through a kiln (and possibly a
preheater system) and exposed to increasingly intense heat, up to 1400
degrees Celcius. This process drives off all moisture, dissociates
carbon dioxide from calcium carbonate, and transforms the raw materials
into new compounds. The output from this process, called clinker, must
be cooled rapidly to prevent further chemical changes. Finally the
clinker is blended with certain additives and ground into a fine powder
to make cement. Following this cement grinding step, the cement is
bagged and transported for sale, or transported in bulk.

Figure 1 shows an overview of the key production steps in cement making.
The box on this figure indicated where we choose to set a system
boundary for this benchmarking analysis. The most energy-intensive stage
of the process is clinker production, which accounts for up to 90
percent of the total energy use. The grinding of raw materials and of
the cement mixture are both electricity-intensive steps and account for
much of the remaining energy used in cement production.

For each of the process steps within the boundary, we focus on the major
energy use at that step; for example, in clinker production we just
include the combustion of fuel to generate the heat required, not the
electricity used to rotate the kiln. Thereby, we are left with three
benchmark categories:

-   Electricity use for raw material preparation,

-   Fossil fuel use for clinker production, and

-   Electricity use for cement grinding (or finish grinding).

![](media/image1.wmf){width="5.7965277777777775in" height="2.4625in"}

> Figure 1: The Cement Production Process

Table 1 provides energy consumption values for the three cement-making
process steps included in the system boundary. The first three rows of
the table present "best practice" estimates of energy use in cement
plants taken from two sources that survey the available technologies for
cement manufacturing (Cembureau 1997, Conroy 1994). For raw material
preparation and cement grinding, the main energy demand is electricity
to power grinding mills, so these estimates are given in terms of kWh
per tonne of material throughput. Energy requirements for cement
grinding are roughly double those for raw material preparation because
the cement is harder and needs to be ground more finely than the raw
materials. An important issue when considering "best practice" energy
requirements for grinding is that energy use is related to the hardness
of the raw materials and the additives included before cement grinding
as well as the desired fineness of the finished product. These features
can vary, so it is important to specify the fineness and composition of
the product when discussing energy use. In this table we have included
information on the fineness of the final product expressed in terms of
cm^2^ per gram of product.

Clinker production accounts for a majority of the energy use in the
cement making process. Multi-stage preheaters and precalciners, which
begin the clinker production process by eliminating water and bound
carbon dioxide from the raw materials before they are sent to the kiln,
are part of any "best practice" cement plant. Using these technologies
energy use is around 3,000 kJ per kilogram of clinker produced. Wet
process cement making uses much more energy, and even under "best
practice" can consume up to 6,000 kJ per kilogram of clinker.

The second half of Table 1 provides examples from actual plant
experience worldwide. Data on clinker production, the most
energy-intensive step, are generally given, while grinding energy data
are less commonly available. The four examples shown all use multi-stage
preheaters and precalciners, and all show energy consumption around what
is expected from the "best practice" information. In general, the energy
use for grinding appears to be higher than the "best practice"
estimates, although for cement grinding comparison is difficult because
the final products vary.

> Table 1: Energy Use Data for Three Cement Making Process Steps, "Best
> Practice" and Actual Performance

+-----+--------------+-----------+------+----------+-------+----------+
|     |              | **Raw     | **   |          | **Ce  |          |
|     |              | Material  | Clin |          | ment\ |          |
|     |              | Prep      | ker\ |          | Grind |          |
|     |              | aration** | Prod |          | ing** |          |
|     |              |           | ucti |          |       |          |
|     |              |           | on** |          |       |          |
+-----+--------------+-----------+------+----------+-------+----------+
| **P |              | **Energy  | **   | **Energy | **Pr  | **Energy |
| lan |              | use\      | Fuel | Use\     | oduct | Use\     |
| t** |              | (kWh/t\   | Us   | (kJ/kg   | Fine  | (kWh/t   |
|     |              | raw       | ed** | cl       | ness\ | c        |
|     |              | meal)**   |      | inker)** | (cm2  | ement)** |
|     |              |           |      |          | /g)** |          |
+-----+--------------+-----------+------+----------+-------+----------+
| >   | Cembureau -- | **13-20** | n/a  | **290    | 3500  | **24.5   |
|  ** | Dry          |           |      | 0-3200** |       | --       |
| Tec |              |           |      |          |       | 36.5**   |
| hni |              |           |      |          |       |          |
| cal |              |           |      |          |       |          |
| >   |              |           |      |          |       |          |
|  Pu |              |           |      |          |       |          |
| bli |              |           |      |          |       |          |
| cat |              |           |      |          |       |          |
| ion |              |           |      |          |       |          |
| s** |              |           |      |          |       |          |
+-----+--------------+-----------+------+----------+-------+----------+
|     | Cembureau -- | **5-13**  | n/a  | Up to    |       |          |
|     | Wet          |           |      | **6000** |       |          |
+-----+--------------+-----------+------+----------+-------+----------+
|     | Conroy's     | **10-11** | C    | **299    | 3600  | **25.0** |
|     | "Modern      |           | oal: | 0-3010** |       |          |
|     | Plant        |           |      |          |       |          |
|     | Design"      |           |      |          |       |          |
+-----+--------------+-----------+------+----------+-------+----------+
| >   | Lampang,\    | **21.4**  | Lign | **3014** | 3300  | *        |
|  ** | Thailand     |           | ite: |          |       | *41.76** |
| Act |              |           |      |          |       |          |
| ual |              |           |      |          |       |          |
| > P |              |           |      |          |       |          |
| lan |              |           |      |          |       |          |
| t** |              |           |      |          |       |          |
| >   |              |           |      |          |       |          |
| > * |              |           |      |          |       |          |
| *Pe |              |           |      |          |       |          |
| rfo |              |           |      |          |       |          |
| rma |              |           |      |          |       |          |
| nce |              |           |      |          |       |          |
| >   |              |           |      |          |       |          |
| Dat |              |           |      |          |       |          |
| a** |              |           |      |          |       |          |
+-----+--------------+-----------+------+----------+-------+----------+
|     | Bernburg,    | n/a       | Lign | **300    | n/a   | **22.8** |
|     | Germany      |           | ite: | 8-3100** |       |          |
+-----+--------------+-----------+------+----------+-------+----------+
|     | Rajashree    | **17-20** | C    | **2931** | 3000  | *        |
|     | Cement,      |           | oal: | (*ex     |       | *31.25** |
|     | India        |           |      | pected*) |       |          |
+-----+--------------+-----------+------+----------+-------+----------+
|     | Tepeaca,\    | n/a       | Fuel | **3030** | n/a   | n/a      |
|     | Mexico       |           | oil: |          |       |          |
+-----+--------------+-----------+------+----------+-------+----------+

Sources: Cembureau, 1997, Conroy, 1994, Philipp et al., 1997, Seigert et
al., 1998, Somani et al., 1997, Turley, 1995

**Process Step Benchmarking in the Iron and Steel Industry**

The manufacture of iron and steel involves a complex production process
of many stages, some of which require very large amounts of energy.
There are a number of alternative pathways through which steel can be
produced (See Figure 2). One way is to begin with the basic raw material
for steel: iron ore. After the ore is mined, it must be prepared for
ironmaking through processes of sintering or pelletizing. Iron exists in
an oxidized state in the ore; to produce the pure metal, the oxygen
needs to be removed through a process called reduction. Reduction is
most commonly done in a blast furnace using a carbon source called coke.
Cokemaking usually occurs at the plant, using metallurgical coal as a
feedstock. The iron ore material and carbon source then enter the
smelting process, a method of ironmaking requiring very high
temperatures (\~1500 ^o^C) and resulting in pure iron in a molten state.
This molten iron then enters the steelmaking process, where it is
treated with oxygen to remove carbon that remains in the iron from the
reduction process. Scrap metal is also added at this stage to moderate
the temperature of the steel, and additives can be introduced to form
various alloys. The resulting liquid steel is then cast into ingots,
strips, or other shapes. These shapes go through various rolling stages
to create the final steel products.

An alternative pathway for steel production relies more heavily on the
use of scrap metal. Scrap metal can be melted in a furnace that uses
large amounts of electricity to bring the temperature of the metal to
\~1900 ^o^C. The resulting molten materials can be treated to remove
impurities, or other additives can be introduced to produce alloys. This
electric arc furnace can also use a form of iron known as sponge iron or
directly reduced iron (DRI) as a feed material. Sponge iron or DRI is
produced when iron ore is directly reduced, usually using natural gas,
at lower temperatures than in reduction with coke (\~800 -- 900 ^o^C).

![](media/image2.wmf){width="3.7618055555555556in"
height="4.340972222222222in"}

> Figure 2: The Iron and Steel Production Process

As Figure 2 indicates, our benchmarking analysis draws a system boundary
to include 6 production steps that include the preparation of materials,
the making of iron, and the making of liquid steel (Ruth et al. 2001).
For this paper we will focus on four of those stages to explain the
benchmarking approach. These stages are part of the "integrated"
steelmaking process: cokemaking, sintering, ironmaking through smelting,
and steelmaking from molten iron.

Energy performance values for the four key integrated process steps are
given in Table 2. These values are taken from the International Iron and
Steel Institute (IISI, 1998), which assessed the state of technology for
the industry and established two energy performance levels: Eco-Tech and
All-Tech. Eco-tech performance is based on the use of technologies and
measures that would be economical for a plant to use. All-Tech includes
technologies that may not be currently economical but lead to greater
energy savings.

There is no difference between the Eco-Tech and All-Tech performance for
steelmaking since it is already an exothermic (energy-releasing)
process. It also appears that at the ironmaking stage, the more advanced
All-Tech uses slightly more energy. In fact, what the summary data does
not reveal is that the All-Tech performance includes an increase in gas
or coal injection into the blast furnace, a practice which may increase
the total energy use but lowers the amount of coke used. Less coke
breeze is also used in the sintering step. Since less coke is needed,
less coke is made, so there are energy savings at that stage. This
illustrates that the benchmarking evaluation tool must account for
energy savings is one stage that arise from changes that occur in
another stage.

If the analytical approach looks at each process step separately and
based only on its own level of throughput, the energy savings that arise
from the interdependence of process stages would be missed. For the iron
and steel industry we address that issues by calculating a 'coke
balance'.[^3] Since the IISI benchmarks at the ironmaking and sintering
stages include a value for coke use, any savings in coke should lead to
savings both in coke use and in the energy used to make coke. To
calculate the coke balance, the amount of coke 'allowed' by the
benchmark is calculated, then the amount produced and the net imports is
subtracted to give the amount of coke production 'avoided'. This amount
is multiplied by the cokemaking benchmarks to determine the energy
saved.

Table 2: Energy Performance at Four Process Steps in Integrated
Steelmaking

+-------------------+-----------+-----------+-----------+-----------+
|                   | #### "Eco |           | #### "All |           |
|                   | -Tech" Pe |           | -Tech" Pe |           |
|                   | rformance |           | rformance |           |
+-------------------+-----------+-----------+-----------+-----------+
|                   | **Fossil  | **Ut      | **Fossil  | **Ut      |
|                   | fuels**   | ilities** | fuels**   | ilities** |
+-------------------+-----------+-----------+-----------+-----------+
| **Cokemaking**\   | 3.2 GJ    | 0.29 GJ   | 2.6 GJ    | -0.85 GJ  |
| (per tonne of     |           | steam\    |           | steam\    |
| coke)             |           | 31 kWh    |           | 31 kWh    |
|                   |           | elec      |           | elec      |
+-------------------+-----------+-----------+-----------+-----------+
| **Sintering**\    | 1.43 GJ   | 77 kWh    | 1.11 GJ   | 69 kWh    |
| (per tonne of     |           | elec      |           | elec      |
| sinter)           |           |           |           |           |
+-------------------+-----------+-----------+-----------+-----------+
| **Ironmaking --\  | 11.53 GJ  | 0.40 GJ   | 11.55 GJ  | 0.38 GJ   |
| Blast Furnace\    |           | steam\    |           | steam\    |
| **(per tonne of   |           | 26 kWh    |           | 9 kWh     |
| hot metal)        |           | elec\     |           | elec\     |
|                   |           | 0.16 GJ   |           | 0.24 GJ   |
|                   |           | O2        |           | O2        |
+-------------------+-----------+-----------+-----------+-----------+
| **Steelmaking --\ | -0.58 GJ  | -0.18 GJ  | -0.58 GJ  | -0.18 GJ  |
| Basic Oxygen      |           | steam\    |           | steam\    |
| Furnace**\        |           | 26 kWh    |           | 26 kWh    |
| (per tonne of     |           | elec,\    |           | elec,\    |
| liquid steel)     |           | 0.42 GJ   |           | 0.42 GJ   |
|                   |           | O2        |           | O2        |
+-------------------+-----------+-----------+-----------+-----------+

**Example: Evaluating Brazilian Iron and Steel Plants**

The approach described above can be tested using a dataset of integrated
iron and steel plants operating in Brazil (ABM, 1999). Four plants were
chosen for the evaluation -- CST, CSN, Usiminas, and Cosipa -- and they
are compared against a benchmark based on the Eco-Tech performance from
IISI.

Table 3 illustrates the comparison of these four facilities. Output
among these plants ranges from 3.5 to 4.7 million tonnes per year and
energy consumption ranges from 16.9 to 21.7 GJ/tonne[^4]. The benchmarks
for the plants vary also, because they make each of the four
intermediate products in different proportions. CST makes the most
sinter of all four facilities, nearly twice as much as Usiminas, which
explains why they have such different benchmark values. Of the four
facilities, only CST shows a negative coke balance, meaning it is the
only plant where less coke is used than is allowed by the benchmarks at
sintering and ironmaking stages. These factors make CST the most
efficient of the facilities examined here, in fact, it scores a
benchmark value below 100%, indicating performs below the benchmark
values set by the IISI publication.

> Table 3: Energy Performance at 4 Brazilian Iron and Steel Plants.

  ---------------------------- ----------- ----------- -------------- ------------
  **Plant Name:**              **CST**     **CSN**     **Usiminas**   **Cosipa**

  **Steel Output               3,817,978   4,711,544   4,023,219      3,519,379
  (tonne/year)**                                                      

  **Energy Consumption         16.90       18.69       17.99          21.11
  (GJ/tonne)**                                                        

  **Energy Benchmark           17.43       15.52       14.68          15.84
  (GJ/tonne)**                                                        

  **Coke Balance (tonne        -0.04       0.04        0.05           0.06
  coke/tonne steel)**                                                 

  **Benchmark Value (%)**      96.0%       121.4%      123.8%         134.6%
  ---------------------------- ----------- ----------- -------------- ------------

This benchmarking approach also allows for comparison at the process
step level. Figure 3 shows how the four Brazilian iron and steel plants
perform at each process step compared to a benchmark based on IISI. The
size of each bar represents how much energy was saved (or used in excess
of the benchmark). Not only did CST perform better than the benchmark on
a total basis, but also at the cokemaking, sintering, and ironmaking
stages. This figure illustrates that the energy accounted for in the
coke balance is small in comparison to savings or excesses at the
process stages.

![](media/image3.wmf){width="5.996527777777778in"
height="2.7465277777777777in"}

Figure 3: Energy Performance of 4 Brazilian Iron and Steel Plants at the
Process Step Level, Relative to Benchmark Values.

**Discussion**

The use of benchmarking has arisen in industry as an important tool for
evaluating performance and making comparisons across plants, sectors, or
time periods. Benchmarks for energy performance have become important
policy tools for governments, incentive programs across sectors, and
public relations tools for a company. As benchmarks become more commonly
used in a variety of situations, it is important that benchmarking
approaches follow some key guidelines to make comparisons fair and
meaningful.

Benchmarks should be set on the basis of energy intensity, preferably
including physical measures of throughput as part of the metric, instead
of economic measures. Since the plants or sectors being compared will be
similar but not identical (or a single plant or sector may be changing
over time), it is important to have an evaluation tool that compensated
for these variations. The process-step approach described in this paper
offers such an evaluation tool. For benchmarking to be meaningful, the
production process used in an industry must be accounted for. A
steelmaking plant that uses 50% recycled steel will have different
energy requirements for one using 10% recycled steel. A country that
imports large amounts of coke will have different energy use patterns
from a country that produces all its coke domestically.

When benchmarks are meaningful, fair, and reliable, they can provide the
basis for important changes in energy efficiency. Benchmarks for an
entire sector can be used by governments to negotiate voluntary
agreements with industries in that sector, whereby companies in that
sector agree to energy efficiency targets suggested by the benchmarks.
Within a sector, benchmarks can show how all companies or plants are
performing, which gives individual plants a perspective on their
performance and an incentive to improve. For these types of programs to
be effective, a solid evaluation tool is needed to convince all
participants of the equity of the process.

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[^1]: For consistency, physical measures of output (i.e. tonnes of steel
    or paper) are preferable, but even these may include important
    differences, such as different steel products or different grades of
    paper. Economic measures of output are much more problematic, since
    product prices and value added can change significantly over time.
    This issue has been discussed in a DOE study (EIA, 1995).

[^2]: Dupont claims to have attained a 10% reduction in energy intensity
    on a global basis in the period 1990 to 1996.

[^3]: In cement production, the amount of clinker used in finished
    cement (the clinker-to-cement ratio) illustrates the interdependence
    of steps in that industry. The authors have done a detailed analysis
    of how that relationship affects energy benchmarks (Ruth et al.
    2000).

[^4]: This calculation is based on an assumption that electricity is
    generated at 33% efficiency and steam is generated at 88%
    efficiency. In actual iron and steel facilities, both steam and
    electricity are generated at the plant to meet some or all of the
    plant's requirements. The performance of these generators and
    boilers would ideally be included in a benchmark analysis, but we
    are limited by data for this analysis.