There are six principle changes to be considered:
- More recent data from winning and refining of oil are available and have been incorporated.
- Closure of old refineries, crackers and commissioning of new plant has made significant changes in feedstock manufacturing efficiencies.
- Changes in national power generation systems have resulted in cleaner and more efficient processes; the most up to date figures are now used.
- Changes in the methodology of data compilation.
- Adoption of a more comprehensive presentation report format providing more transparency.
- Some polymer groups have provided new polymerisation data.
Oil winning, refinery, cracker and changes in power generation
Additional oil and gas feedstock data are incorporated, the number of refineries providing data has doubled. Of the 19 crackers providing data for the old reports two have now been closed down and data from 7 more included. This effectively lowers the overall values, improves data quality and narrows the range. The new cracker data are the most significant change and clearly reflect the real position as it is today. There has been some upgrading of the various countries’ power generation systems, particularly in the UK, as generators move to cleaner fuels like gas, reduce coal usage and at the same time install flue gas scrubbers. The main effect has been to reduce emissions or change levels and output allocation.
- It is the combination of these upstream, changes that has had the most impact since they feed through into the respective polymer data and all downstream, values are changed as a consequence.
Methodology changes
The methodology describes how the data has been collated, classified and what conventions have been used to do this; for example, where two products are manufactured in one process it describes what share of the burdens should be allocated to each of the products.
Condensate and recovered steam are now allocated and accounted for in much better detail than in the first reports. Energy credits and debits are better defined, allocated and reported, while data on losses due to transport and recovery are more robust.
Waste that could be recovered externally has been disclosed in the new tables but not allocated as a credit. This allows it to be credited by the user of the data depending upon specific circumstances.
The use of and sources of process water and cooling water are now better defined. Water sources are now listed and specific use classified separately, e.g., distinction between cooling and process water, distinction between the sources of such water. Landlocked companies use re-circulating sources (recorded as a small consumption), others use sea water on a once through system. A gross water resources table is now incorporated.
Presentation
In addition to the modern electronic format, the standardisation of Life Cycle Assessmemt (LCA) has helped to initiate a change which separates out in much clearer detail how energy is supplied and used and how the contributions to emissions arise and are allocated. For example, the new method for energy reporting includes an additional transport allocation, the new tables take the form:
The importance of this breakdown is to illustrate the contribution controlled by the polymer industry separately from what is contributed by the fuel producing industries, e.g., the national power generation systems and transport factors.
A further classification of energy consumption allocates the actual source of the energy in terms of primary fuels, i.e., coal, oil, gas, nuclear, hydro, wood, biomass as well as energy recovered from steam or condensate. The feedstock energy is the amount of fuels fed into the production system that is used as a material rather than being burned. Part of the feedstock energy is retained in the polymer and available for reuse – either by material recycling or recovery of the calorific value by use as a fuel – whichever is environmentally appropriate.
A breakdown and classification of water and air emissions similar to the one for energy consumption is given, so it is easier to see which emissions arise from the fuel producing industries and transport operations compared to those from the actual manufacturing process.
Air emission "hydrocarbons" have been delineated to isolate methane, a global warming gas
The solid waste classification is better defined, for example :
- Mineral waste: - is waste earth & rock from mining and/or coal production.
- Slags and Ash: - are from industrial boilers and furnaces, usually inert. If used in road construction it is classified as a product and not a waste.
- Inert or regulated: - Waste from chemical processes is classified as one of these forms. The former could in principle be sent to landfill but the latter needs to be treated or put in regulated storage.
- Mixed industrial: - covers all other wastes, usually discarded industrial packaging or general housekeeping waste.
- Construction waste: - has been reported by some and is therefore included.
- Unspecified: - waste that is not clarified but could probably be part of mixed industrial if examined in greater detail.
Waste that can be recovered is noted, for example as energy or recycling
And finally the treatment of water usage was always an item of constant inquiry, it was not clear what was actually used in the process and what was used as cooling water. Water has therefore been given its own table and separated into cooling water and process water. Cooling water may be drawn directly from a river, canal or even the sea and is returned after use. Many plants, however, operate a recirculating water system in which the water is commonly sent to a cooling tower before being returned to a pond ready for re-use. For such systems, the cooling water requirement appearing in the raw materials table, refers to the net amount drawn from the environment which primarily is the top-up water that is added to the system from time-to-time to make up any losses. So differences between the given data and those of other textbooks may be caused by the amount of recirculating water use.