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Previous studies showed that using carbon dioxide (CO2) as a raw material for chemical syntheses may provide an opportunity for achieving greenhouse gas (GHG) savings and a low-carbon economy. Nevertheless, it is not clear whether carbon capture and utilization benefits the environment in terms of resource efficiency. We analyzed the production of methane, methanol, and synthesis gas as basic chemicals and derived polyoxymethylene, polyethylene, and polypropylene as polymers by calculating the output-oriented indicator global warming impact (GWI) and the resource-based indicators raw material input (RMI) and total material requirement (TMR) on a cradle-to-gate basis. As carbon source, we analyzed the capturing of CO2 from air, raw biogas, cement plants, lignite-fired power, and municipal waste incineration plants. Wind power serves as an energy source for hydrogen production. Our data were derived from both industrial processes and process simulations. The results demonstrate that the analyzed CO2-based process chains reduce the amount of GHG emissions in comparison to the conventional ones. At the same time, the CO2-based process chains require an increased amount of (abiotic) resources. This trade-off between decreased GHG emissions and increased resource use is assessed. The decision about whether or not to recycle CO2 into hydrocarbons depends largely on the source and amount of energy used to produce hydrogen.
The growing demand for timber, in particular for renewable energy, increases pressures on global forests and requires a robust monitoring system to ensure sustainability. This article takes a first step toward more systemic monitoring by asking how the global use of forests by EU consumers can be accounted for. Specifically, this article builds on and develops the method of global land use accounting to account for the EU-27's consumption of primary timber between 2002 and 2011 in terms of both volume and forest area. It assesses international trade flows for around 100 commodities and converts them into a volume of primary raw timber based on conversion values. Results reveal that both imports and exports increased over the assessed time period, with primary EU-27 timber estimated to be around 1 m3/cap in 2011. Gaps, uncertainty and a lack of harmonization regarding especially trade data and conversion values are key challenges to further improving the robustness of the method and reliability of results. Future research may focus on improving the method to address in particular recycled and recovered flows as well as the question of whether area or volume is the most appropriate metric for further development of a forest footprint indicator.
The contribution of the EU bioeconomy to sustainable development depends on how it is implemented. A high innovation potential is accompanied by considerable risks, in particular regarding the exacerbation of global land use conflicts. This article argues that a systemic monitoring system capable of connecting human-environment interactions and multiple scales of analysis in a dynamic way is needed to ensure that the EU bioeconomy transition meets overarching goals, like the Sustainable Development Goals. The monitoring should be centered around a dashboard of key indicators and targets covering environmental, economic, and social aspects of the bioeconomy. With a focus on the land dimension, this article examines the strengths and weakness of different economic, environmental and integrated models and methods for monitoring and forecasting the development of the EU bioeconomy. The state of research on key indicators and targets, as well as research needs to integrate these aspects into existing modeling approaches, are assessed. The article concludes with key criteria for a systemic bioeconomy monitoring system.
Biodiversity loss is widely recognized as a serious global environmental change process. While large-scale metal mining activities do not belong to the top drivers of such change, these operations exert or may intensify pressures on biodiversity by adversely changing habitats, directly and indirectly, at local and regional scales. So far, analyses of global spatial dynamics of mining and its burden on biodiversity focused on the overlap between mines and protected areas or areas of high value for conservation. However, it is less clear how operating metal mines are globally exerting pressure on zones of different biodiversity richness; a similar gap exists for unmined but known mineral deposits. By using vascular plants' diversity as a proxy to quantify overall biodiversity, this study provides a first examination of the global spatial distribution of mines and deposits for five key metals across different biodiversity zones. The results indicate that mines and deposits are not randomly distributed, but concentrated within intermediate and high diversity zones, especially bauxite and silver. In contrast, iron, gold, and copper mines and deposits are closer to a more proportional distribution while showing a high concentration in the intermediate biodiversity zone. Considering the five metals together, 63% and 61% of available mines and deposits, respectively, are located in intermediate diversity zones, comprising 52% of the global land terrestrial surface. 23% of mines and 20% of ore deposits are located in areas of high plant diversity, covering 17% of the land. 13% of mines and 19% of deposits are in areas of low plant diversity, comprising 31% of the land surface. Thus, there seems to be potential for opening new mines in areas of low biodiversity in the future.
Poor sustainability and increasing economic shortcomings in fossil raw material use besides further technical developments of substitutes lead to a growing potential for CO2-utilisation. Hence, we balanced CO2-based methane and methanol production in a life cycle assessment and identified CO2-utilisation as a greenhouse gas saving method. However, it requires a lot of renewable energy.
In the future, the capacities of renewable SNG (synthetic natural gas) will expand significantly. Pilot plants are underway to use surplus renewable power, mainly from wind, for electrolysis and the production of hydrogen, which is methanated and fed into the existing gas pipeline grid. Pilot projects aim at the energetic use of SNG for households and transport in particular for gas fueled cars. Another option could be the use of SNG as feedstock in chemical industry.
The early stage of development raises the question of whether SNG should be better used for mobility or the production of chemicals. This study compares the global warming potential (GWP) of the production of fossil natural gas (NG) and carbon-dioxide (CO2)-based SNG and its use for car transport versus chemical use in the form of synthesis gas. Since the potential of wind energy for SNG production is mainly located in northern Germany, the consequences by a growing distance between production in the North and transport to the South of Germany are also examined.
The results indicate that CO2-based SNG produced with wind power would lead to lower GWP when substituting NG for both uses in either transport or chemical production. Differences of the savings potential occur in short-distance pipeline transport. The critical factor is the energy required for compression along the process chain.
The amount of land directly disturbed by mining is a key generic environmental pressure indicator. A novel method based on the measurement of the cumulative net area disturbances using Landsat satellite images and its correlation with the cumulative ore production at the mine site was applied. Weighted disturbance rates (WDRs) were calculated indicating the annual quantity of hectares newly disturbed per million metric tons of ore extracted. Results show that open pit (OP) have a smaller average WDR (5.05 ha/Mt) than underground (UG) mines (11.85 ha/Mt). This is explained by the relation between the annual amounts of new net area disturbed and of ore extracted which is larger for UG than for OP mines due to the annual extraction volume (lower for UG). Overall findings demonstrate that bauxite mining has the highest WDR (7.98 ha/Mt), followed by gold (6.70 ha/Mt), silver (5.53 ha/Mt), copper (4.5 ha/Mt) and iron (4.25 ha/Mt).
Material flows induced by national economies can be regarded as indirect pressure indicators for environmental degradation. Economy-wide material flow analysis and indicators have been designed to monitor material and energy flows at the macroeconomic level and to provide indicators, which could contribute to management of resourceuse and output emission flows from both economic, environmental and broader sustainability points of view. These indicators can serve various purposes including monitoring the material basis of national economies and related environmental pressures, assessment of the material and resource productivity and monitoring the implications of trade and globalisation.
The main part of this paper compares the material and resourceuse of the Czech Republic, Germany and the EU-15 by means of DMI and TMR indicators over the period of 1991–2004 (1991–2000 for EU-15). At the aggregate level both indicators in all three economies do not show any clear decreasing or increasing trends over the period considered. This means that environmental pressure related to use of materials for production and consumption purposes remains rather stable. All the economies however, recorded an increase in the efficiency of transforming the material/resource inputs into economic output. The analysis further revealed that most of the dynamics of DMI and TMR in the Czech Republic tended towards a higher similarity with Germany and the EU-15. In the future, further decreases in DMI as well as in TMR of fossils fuels might be expected in the Czech Republic, which could be counteracted by increase in DMI and TMR of metal ores/metal resources and non-metallic minerals/non-metallic resources. The future development of total DMI, TMR and material/resource intensity in both the Czech Republic and Germany will depend on further shifts to less material intensive industries and services and on increasing material efficiency in production and consumption of particular products. This is not only a technological, but also a social challenge, as there are barriers in current mode of governance and in shaping of current economic and social systems to do so.
This contribution presents the state of the art of economy-wide material flow accounting. Starting from a brief recollection of the intellectual and policy history of this approach, we outline system definition, key methodological assumptions, and derived indicators. The next section makes an effort to establish data reliability and uncertainty for a number of existing multinational (European and global) material flow accounting (MFA) data compilations and discusses sources of inconsistencies and variations for some indicators and trends. The results show that the methodology has reached a certain maturity: Coefficients of variation between databases lie in the range of 10% to 20%, and correlations between databases across countries amount to an average R2 of 0.95. After discussing some of the research frontiers for further methodological development, we conclude that the material flow accounting framework and the data generated have reached a maturity that warrants material flow indicators to complement traditional economic and demographic information in providing a sound basis for discussing national and international policies for sustainable resource use.
Comparative analysis of environmental impacts of maize-biogas and photovoltaics on a land use basis
(2010)
This study aims to stimulate the discussion on how to optimize a sustainable energy mix from an environmental perspective and how to apply existing renewable energy sources in the most efficient way. Ground-mounted photovoltaics (PV) and the maize-biogas-electricity route are compared with regard to their potential to mitigate environmental pressure, assuming that a given agricultural area is available for energy production. Existing life cycle assessment (LCA) studies are taken as abasis to analyse environmental impacts of those technologies in relation to conventional technology for power and heat generation. The life-cycle-wide mitigation potential per area used is calculated for the impact categories non-renewable energy input, green house gas (GHG) emissions, acidification and eutrophication. The environmental performance of each system depends on the scenario that is assumed for end energy use (electricity and heat supply have been contemplated). In all scenarios under consideration, PV turns out to be superior to biogas in almost all studied impact categories. Even when maize is used for electricity production in connection with very efficient heat usage, and reduced PV performance is assumed to account for intermittence, PV can still mitigate about four times the amount of green house gas emissions and non-renewable energy input compared to maize-biogas. Soil erosion, which can be entirely avoided with PV, exceeds soil renewal rates roughly 20-fold on maize fields. Regarding the overall Eco-indicator 99 (H) score under most favourable assumptions for the maize–biogas route, PV has still a more than 100% higher potential to mitigate environmental burden. At present, the key advantages of biogas are its price and its availability without intermittence. In the long run, and with respect to more efficient land use, biogas might preferably be produced from organic waste or manure, whereas PV should be integrated into buildings and infrastructures.