Closing carbon cycles

Fossil fuels are used as raw materials for the manufacture of synthetic organic materials, e.g. plastics, fibres, synthetic rubber, paints, solvents, fertilisers, surfactants, lubricants and bitumen. Since fossil carbon is embodied in these products they may be particularly relevant to climate change. This thesis analyses the production, use and waste management of synthetic organic materials. The main research questions are to determine · how much the production and waste management of synthetic organic materials contribute to the release of CO2 emissions and · to what extent these emissions could be reduced in the short term by improved material management, including recycling, re-use, energy recovery and the use of bio-based resources as feedstocks. The thesis aims to answer these research questions for Germany, which accounts for about one quarter of the total production of synthetic organic materials and products in Western Europe. In Chapter 2, firstly a Material Flow Analysis (MFA) is conducted and secondly, the IPCC Reference Approach is applied. A prerequisite for the application of both methods is that statistical data for carbon feedstocks as published in national energy balances comply with a common definition. The analyses for Germany, Italy and the Netherlands show that this is not always the case a fact which shows the importance of data harmonisation. If harmonised data are used for Germany the results determined according to the two methods correspond well. In Chapter 3, a model to estimate a the total amount of plastics waste in a country is developed and applied. According to the model results for Germany the amount of post-consumer plastics waste will rise from 4.6 Mt in 1995 to 6.2-7.2 Mt in 2005 and could easily reach a value in the range of 12-14 Mt in 2025. Chapter 4 studies the energy requirements and the CO2 emissions related to the production of organic intermediates and plastics. In Chapter 5 and 6, surfactants made from vegetable oils are compared to petrochemical surfactants and to biodiesel with regard to energy use and CO2 emissions. One important finding is that the savings of non-renewable energy and the reduction in greenhouse gas emissions are higher if vegetable oils are used as a feedstock to produce chemicals compared to their use for biofuels. Chapter 7 analyses recycling and energy recovery strategies for post-consumer plastics. Based on the results of earlier chapters, Chapter 8 studies the total system of production and waste management of synthetic organic materials in Germany in present and future. In 1995, the entire system required 1700 PJ of non-renewable primary energy and 57 Mt CO2 of fossil origin were emitted. The technical saving potential by the year 2005 is estimated at 220 PJ of energy and 14 Mt of CO2. These figures include the use of waste as a resource (recycling, re-use, energy recovery) and material production using biomass-derived feedstocks. If compared to the figures for 1995, these savings are equivalent to 13% for energy and 24% for CO2. Compared to the total German economy in 1995 the savings are equivalent to 1.5% both for energy and CO2. It is concluded that the potential for CO2 mitigation related to synthetic organic materials should be given more attention in future.