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Lechtenbohmer S.,Wuppertal Institute for Climate | Lechtenbohmer S.,Wuppertal Institute For Klima Umwelt Energie | Barthel C.,Wuppertal Institute for Climate | Merten F.,Wuppertal Institute for Climate | And 3 more authors.

Preventing the worst consequences of climate change would require that GHG emissions be reduced to levels near zero by the middle of the century. To respond to such a daunting challenge, we need to rethink and redesign the currently highly energy-dependent infrastructures of industrial societies and particularly the urban infrastructures to become low- or even zero-carbon cities. Sustainable urban infrastructures need technology. In this paper focused on Western European Cities, we discuss a wide set of technologies in the fields of building, energy and transport infrastructures that can significantly contribute to a reduction of energy and/or GHG emissions and are already available or are in the pipeline. Based on the review of a recent study for the city of Munich, we then present how a mix of these technologies could reduce CO2-emissions by up to 90% for the metropolis of 1.3 million inhabitants and that this strategy could be economically attractive despite a high initial investment. All of the residential buildings of a city like Munich could be entirely redesigned for Ie{cyrillic, ukrainian}200 per inhabitant annually, which is about one third of an average annual natural gas bill. © Author(s) 2010. Source

Arnold K.,Wuppertal Institute For Klima Umwelt Energie | Dienst C.,Wuppertal Institute For Klima Umwelt Energie | Lechtenbohmer S.,Wuppertal Institute For Klima Umwelt Energie
Umweltwissenschaften und Schadstoff-Forschung

Background The use of natural gas has increased in the last years. In the future, its import supply and transport structure will diversify (longer distances, higher share of LNG (liquefied natural gas), new pipelines). Thus the process chain and GHG emissions of the production, processing, transport and distribution might change. Simultaneously, the injection of bio methane into the natural gas grid is becoming more important. Although its combustion is regarded as climate neutral, during the production processes of bio methane GHG emissions are caused. The GHG emissions occurring during the process chain of energy fuels are relevant for the discussion on climate policy and decision making processes. They are becoming even more important, considering the new Fuel Quality Directive of the EU (Dec. 2008), which aims at controlling emissions of the fuel process chains. Aim In the context of the aspects outlined above the aim is to determine the future development of gas supply for Germany and the resulting changes in GHG emissions of the whole process chain of natural gas and bio methane. With the help of two gas consumption scenarios and an LCA of bio methane, the amount of future emissions and emission paths until 2030 can be assessed and used to guide decision processes in energy policy. Results and discussion The process chain of bio methane and its future technical development are outlined and the related emissions calculated. The analysis is based on an accompanying research study on the injection of bio methane to the German gas grid. Two types of biogas plants have been considered whereof the "optimised technology" is assumed to dominate the future market. This is the one which widely exploits the potential of process optimisation of the current "state of the art" plant. The specific GHG emissions of the process chain can thus be nearly halved from currently 27.8 t CO 2-eq./TJ to 14.8 t CO2-eq./TJ in 2030. GHG emissions of the natural gas process chain have been analysed in detail in a previous article. Significant modifications and a decrease of specific emissions is possible, depending on the level of investment in the modernisation of the gas infrastructure and the process improvements. These mitigation options might neutralise the emission increase resulting from longer distances and energy intensive processes. In the last section two scenarios (low and high consumption) illustrate the possible development of the German gas supply until 2030, given an overall share of 8-12 % of bio methane. Considering the dynamic emission factors calculated in the former sections, the overall gas emissions and average specific emissions of German gas supply can be given. The current emissions of 215.4 million t CO2-eq. are reduced by 25 % in the low-consumption scenario (162 million t CO2-eq.), where consumption is reduced by 17 %. Assuming a consumption which is increased by 17 % in 2030, emissions are around 7 % higher (230.9 million t CO2-eq.) than today. Conclusions Gaseous fuels will still play a significant role for the German energy supply in the next two decades. The GHG emissions mainly depend on the amount of gas used. Thus, energy efficiency will be a key issue in the climate and energy related policy discussion. A higher share of bio methane and high investments in mitigation and best available technologies can significantly reduce the emissions of the process chain. The combustion of bio methane is climate neutral compared to 56 t CO2/TJ caused by the direct combustion of natural gas (or 111 t CO2/TJ emitted by lignite). The advantage of gaseous energy carriers with the lowest levels of GHG emissions compared to other fossil fuels still remains. This holds true for fossil natural gas alone as well as for the expected future blend with bio-methane. © Springer-Verlag 2010. Source

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