3. Benchmarking Results

The results of the benchmarking project are presented in three sections:

Section 3.1: Benchmarking Energy Efficiency and CO₂ Emissions of Canadian Ammonia Producers (2000–2002) – This section provides an overview of the data for the Canadian industry, describes the operations involved in the project and presents data on energy efficiencies and CO₂ emissions for the sector.

Section 3.2: Global Energy Efficiency and CO₂ Emissions Comparisons (2002) – Canadian ammonia plant energy efficiencies and CO₂ emissions were compared with those of other ammonia plants throughout the world. Results were reported by global regions. Ammonia and urea productions used in this report are based on the International Fertilizer Development Center’s worldwide plant capacity data.

Section 3.3: “World Top” Performance and Future Projections – This section reviews where Canadian facilities rank versus “world top” performance. A look at future low-energy designs is also included.

Section 3.1: Benchmarking Energy Efficiency and CO₂ Emissions of Canadian Ammonia Producers (2000–2002)

Currently, there are 11 ammonia plants operating in Canada. A list of the 10 Canadian ammonia plants operated by six companies that participated in the benchmarking study and the corresponding rated production capacity are provided in Table 1 below.

* Note: All facilities use natural gas feedstock for ammonia production except Joffre, which uses by-product hydrogen stream. Joffre plant data are not included in inter-plant comparisons that include feedstock energy data.

3.1.1 Ammonia Production and Energy Use

Average annual net energy efficiency for the 10 Canadian plants over the three-year benchmarking study remained constant at 33.8 GJ/t NH₃, as shown in Figure 2. However, the feedstock and fuel energy has decreased from 33.5 to 32.8 GJ/t NH₃. This 2 percent improvement resulted in the same percentage reduction in CO₂ generation. Net energy remained constant since other energy use offset the reduction in feedstock and fuel energy.

The three-year average normalized or net ammonia plant energy efficiencies for the natural gas feedstock Canadian plants are shown in Figure 3. The efficiencies of the nine natural gas-based plants range from 29.7 to 42.3 GJ/t NH₃, with an average for natural gas plants (NG) of 34.4 GJ/t NH₃. The group average is 33.2 GJ/t NH₃, with the hydrogen-based plant included. The most energy-efficient plant uses approximately 70 percent of the energy used by the least energy-efficient plant, per tonne of ammonia production.

3.1.2 Ammonia Production and CO₂ Emissions

Canadian ammonia plants generate 7 459 188 t/yr CO₂ (average over 2000–2002). All of the natural gas-based ammonia plants in Canada also produce urea. Urea production combines two molecules of ammonia with one molecule of CO₂ to form urea and water in solution. The urea solution is evaporated to form urea granular fertilizer. A total of 3 013 689 t/yr CO₂ is used for urea production. This is a 40 percent recovery factor for CO₂ that would otherwise be emitted to the atmosphere.

Specific CO₂ generation ranges from 1.66 to 1.98 t CO₂/t NH₃ for the natural gas feedstock ammonia plants (as shown in Table 2). The variability is primarily due to the energy efficiency of the plant and, to a lesser extent, the carbon content of the feedstock and fuel (see Factors that influence energy efficiency and CO₂ emissions production). More energy-efficient plants have a lower specific CO₂ generation since less fuel and feedstock are used to produce the same amount of ammonia.

The favourable impact of recovering some of the process-generated CO₂ is shown in Figure 4. Because all the natural gas-based plants are associated with urea plants, they recover otherwise vented CO₂ for urea production. Specific recovery ranges from 0.30 to 1.11 t CO₂/t NH₃ for an overall average of 0.61 t CO₂/t NH₃.

The resulting total CO₂ emissions from ammonia facilities (total generated – total recovered) range from 0.55 to 1.68 t CO₂/t NH₃, with average specific CO₂ emissions of 1.07 t CO₂/t NH₃ from natural gas-based plants. The specific CO₂ emissions levels for each plant are also presented in Figure 4.

Section 3.2: Global Energy Efficiency and CO₂ Emissions Comparisons (2002)

Canadian ammonia plant energy efficiencies and CO₂ emissions were compared with those of other ammonia plants throughout the world. There are 71 countries that produce ammonia and 58 that produce urea. For reporting purposes, these countries were grouped into 13 regions (Table 3). Ammonia and urea productions used in this report are based on the International Fertilizer Development Center’s worldwide plant capacity data.

3.2.1 Ammonia Production Energy Efficiencies

CO₂ generation and emissions from ammonia plants are calculated using feed plus fuel energy (FFE) efficiencies rather than net energy efficiencies. FFE relates directly to the CO₂ generated within the ammonia plant, whereas net energy efficiencies include electrical usage and adjustments for other energy debits and credits, which can have associated offsite CO₂ emissions not directly from the ammonia plant.

Estimated FFE efficiencies for each global region are shown in Figure 5. These range from 33.1 to 40.4 GJ/t NH₃, with a world average of 38.6 GJ/t NH₃. Canada ranks first in having the most FFE-efficient plants. These plants generate the least amount of CO₂/NH₃ production.

3.2.2 Estimated CO₂ Emissions From Ammonia Production

CO₂ emissions were calculated using ammonia and urea production estimates and a 79.5 percent capacity utilization for each global region. Canadian estimates were based on actual 2002 production from the nine natural gas-based ammonia plants. CO₂ emissions from ammonia production are derived from the combustion of natural gas used as a fuel and from the steam reformation process used to derive the hydrogen stream from the natural gas used as a feedstock. These CO₂ emissions streams are referred to as fuel and process (or feed) respectively.

Total world ammonia production for 2002 is estimated to be 128 megatonnes (Mt). Total CO₂ generation from these ammonia plants is estimated to be 275 Mt. Approximately 62 percent, or 170 Mt CO₂, is process- or feed-related. A significant amount (28.5 percent) of total CO₂ generated is recovered for use in urea production, leaving CO₂ emissions of 197 Mt from ammonia plants throughout the world. The global CO₂ generation and emissions estimates for 2002 are summarized in Figure 6.

Gross CO₂ generation from ammonia plants and emissions net of CO₂ used in urea production in the various regions of the world are shown in Figure 7. China ranks first with the highest CO₂ emissions (21.9 percent), and Oceania has the least. Canada is among the regions with the least CO₂ emissions, ranking 11th (highest to lowest), and emits 2.2 percent of the world’s total CO₂ from ammonia plants.

On a per tonne of production basis, CO₂ generation from ammonia production ranges from 1.84 to 2.24 t CO₂/t NH₃, with a world average of 2.14 t CO₂/t NH₃. Canada and Western Europe are the most efficient regions, with generation factors of 1.81 and 1.84 respectively.

When the CO₂ that has been captured and used in urea production is accounted for, total CO₂ emissions from ammonia production range from 0.91 to 2.23 t CO₂/t NH₃. Canada is the second-lowest region in terms of emissions per tonne of ammonia production, at 1.11 t CO₂/t NH₃. Figure 8 presents the specific CO₂ generation and emissions rates by region for 2002.

Section 3.3: “World Top” Performance and Future Projections

3.3.1 Worldwide Benchmarking

Nearly all the worldwide commercial production of ammonia is from hydrocarbon feedstocks and fuels. As mentioned previously, improving the energy efficiency of ammonia production is an important strategy to reduce CO₂ emissions.

Benchmarking the energy efficiency of individual ammonia plants is an effective way to measure plant performance against other producers and determine the best performers in the world. It provides a quantitative measure of what is possible with today’s technology and can be used to assess the feasibility of making improvements. Figure 9 shows the performance of the individual Canadian ammonia plants against other plants around the globe.

3.3.2 Canada in “World Top” Rankings

A “world top” rating ranks plants in 10 groups according to energy efficiency. If a plant is ranked in the top group, it is considered world top. An ammonia plant with an energy efficiency of 32.6 GJ/t NH₃ or lower is considered to be world top. As noted previously, Canadian ammonia production is energy efficient. Comparing global regions, the nine Canadian ammonia producers are the second-most efficient, following the Western European producers. The average net energy efficiency of the nine Canadian producers is 34.1 GJ/t NH₃. This is 11 percent better than the world average of 38.5 GJ/t NH₃.

3.3.3 The Future of Ammonia Plant Low-Energy Designs

Modern ammonia production technology began in the 1960s. The energy efficiency of these plants was typically 39.5 GJ/t. The efficiency of newly designed plants improved substantially, as numerous innovative concepts were developed. Designs of 28.0 GJ/t became available in 1991. Since then, improvements have continued but at a much reduced rate. Currently, low energy designs approaching 27.0 GJ/t are being offered.

The best estimate of future improvements in the efficiency of low-energy ammonia plants comes from Ammonia: Principles and Industrial Practice. After an extensive review of the history of industrial ammonia production and current technologies, the author, Max Appl, makes the following broad predictions:

• Natural gas will remain the preferred feedstock for at least the next 10 to 15 years. Coal gasification will not play a major role in ammonia production in that period.
• The present ammonia technology will not change fundamentally, at least in the next 10 to 15 years. Even if there are radical, unforeseeable developments, they will take time to reach commercial introduction.
• With the traditional concepts, the margins of additional improvements have become small after years of intensive research and development.
• Only minor improvements of individual steps, catalysts and equipment are expected.
• There is unlikely to be any further significant reduction in the energy consumption of the natural-gas-based steam-reforming ammonia process; figures between 27 and 28 GJ/t are already close to the theoretical minimum, which is 20.9 GJ/t.
• For the next 10 to 15 years, the bulk of ammonia production will still be produced in world-scale plants of 1000–2000 tonnes per day NH₃. Small capacity plants will be limited to locations where special logistical, financial or feedstock conditions favour them.
• New developments in ammonia technology will mainly reduce investment costs and increase operational reliability. Smaller integrated process units contribute to this reduction and give additional savings by simplifying piping and instrumentation. Reliability may be improved by advances in catalyst and equipment quality and by improved instrumentation and computer control.

With this forecast in mind, the improvement in the consumption of fuel energy of new low-energy design plants is estimated to continue at a slower rate than that experienced over 1991–2003, where the Energy Improvement Factor (EIF) averaged 1.0 percent of the fuel per year. From now through 2014, it is estimated that the fuel consumption improvement will be 35 percent less than that during the previous decade. This equates to a 0.65 percent per year EIF. The energy efficiency of these low-energy designs is expected to drop from 6.2 to 5.8 GJ/t, while process efficiency will remain fixed by chemistry. The total energy efficiency in 2014 will be 26.7 GJ/t.

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