Energy I: LCM in the Energy Sector I
Life cycle management of F-gas-free refrigeration technology: The case of F-gases-free frozen dessert equipments
Commercial refrigeration covers a large variety of appliances used in several environments such as supermarkets, restaurant, hotels, pubs and café.
These products are estimated to consume an important portion of electricity in Europe. Moreover, they may cause other negative environmental impacts during their life-cycle due to their material content such as refrigerants and insulating agents. The commercial refrigeration is one of biggest emitters of HFCs emissions (23%). HFCs are used as refrigerants and foam-blowing agents and emitted as leakage from refrigeration systems. They have a global warming potential similar to that of HCFCs and hundreds to thousands of times greater than carbon dioxide.
For the refrigerant sector, the aim of reducing the impact on climate change could be achieved by applying some innovative technologies, which allow to obtain the replacing of refrigerants with HFC-free refrigerants, the using of HFC-free insulation material and the energy consumption reducing.
Carpigiani is one of larger manufacturer of frozen dessert equipment worldwide. The traditional refrigeration system of the ice-cream machines is based on HFC-gas (R404A). Carpigiani is moving towards new F-gas-free techonologies (based on carbon dioxide, R744 and propane, R290). These cooling agents guarantee the same machine’s perfomances with the additional advantage of very low impacts on global warming potential. The CO2-based technology operates at a higher pressure than HFCs and requires new system design and new components. Experimental tests have proven the technical feasibility of the ice-cream machine based on CO2 and have led Carpigiani to realize a prototype. In collaboration with ENEA, a Life Cycle Assessment study has been carried out to assess the environmental performances of the CO2-prototype in comparison with the traditional HFC-based machine. The functional unit is the ice-cream production for 10 years (lifetime of the machine). The comparative analysis has been realized with GaBi4 software and has taken into account only the lifecycle phases, the materials and the energy flows which are different for the two machines. The input data include the energy consumption (during use and end-of-life phase) and the different amounts of materials, mainly iron and copper, used in tubes, in the compressor, in the intercooler and into the gas cooler. The environmental performance of the two systems were analyzed by CML 2001(December2007) as evaluation method. The results prove that the innovative CO2-based machine shows best environmental performances. In particular, the reduced impacts concern the energy consumption(-23%), the global warming potential(-22%) and the ozone layer depletion(80%).
How gas turbines running on alternative fuels could reduce the life cycle impact of electricity generation considering geographical specificities
1CIRAIG Research Center, Canada; 2Rolls-Royce Canada, Canada; 3HEC Montréal, Canada
The advantages of gas turbines for electricity generation applications are numerous, particularly considering their high fuel efficiency in combined cycle and lower overall air emissions per MJ of generated electricity compared to conventional fossil fuel technology. Research and development on new turbine designs and operating parameters, adapted for use of novel fuels, are presently carried out, and identifying which fuel has lower potential environmental impacts in a life cycle perspective remains an integral part of the process.
Due to different trading issues and in order to ensure secure fuel supply, the operation of an alternative fuel power plant would more realistically be located in the country where the respective fuel was produced, making their relative environmental impact dependant of the country’s specificities. With this in mind, certainly decision makers could raise the following questions: 1) in which geographical context would the benefits be most substantial? And 2), for which alternative fuel? Hence a consequential LCA positioned in 2020, assessing the impacts of gas turbine utilizing different alternative fuels in several countries was performed. The regions studied are the United States, Germany, Indonesia, Brazil, China and Italy, regions all chosen for their potential alternative fuel supply. The liquid and gaseous fuels considered are syngas, biogas, bio-ethanol and biodiesel from a variety of feedstock. In the case of fuels produced from constrained sources such as tallow and MSW, indirect effects were accounted for due to their inelastic supply. Certainly, a diversion of these materials to bioenergy application would reduce their availability and current users would substitute these materials. As well, the assessment of both energy crops required looking at direct and indirect land use changes from these additional cultivations. For each scenario studied an electricity substitution occurred, again specific to the countries specificities and influenced significantly the impact results. Results show that biogas from manure and organic fraction of municipal wastes and syngas from forest residues have the lowest overall potential environmental impacts due to low environmental burdens related to the fuel production. Biodiesel from tallow showed higher impacts as well as syngas from coal independently from its geographical context. Finally, the alternative fuels generally showed lower impacts then the energy source they would substitute.
Potential of microalgae for sustainable energy production
KIT Karlsruhe Institute of Technology, Germany
According to the mandatory target by the renewable Energy Directive, by 2020, 20% of the energy consumption in Europe should come from renewable energy sources. Research on novel technologies seeks to enhance efficiency of bioenergy and to support provision of sustainable technologies as a general goal.
Microalgae, such as green algae and cyanobacteria generate biomass by photosynthesis. The biomass is a form of chemical energy which can be further converted into hydrogen, biodiesel or other forms of liquid or gaseous fuels. The production of energy with microalgae may be superior to competing technologies concerning some important criteria: algae can be grown in closed systems on non-arable land, need CO2 as only carbon source and can also grow in salt or wastewater. However, up to now (based on lab and small pilot plant experiences) net energy generation from microalgae is negative. Progress in the development of bioreactors therefore will have to ensure a positive energy balance as basic requirement.
By now, new concepts of energy production with microalgae are arising: microalgae have already been used to produce high value chemicals, such as proteins or colorants for food and chemical industry. Integrating biomass and energy production into a larger system may lead to synergy effects and an overall positive net energy generation. Above that, for a sustainable energy supply, the production process should be as well as competitive concerning economic and ecologic criteria.
In this work a detailed material flow based life cycle model of different processes of algal energy production is created. Within this model, potential systems of algal energy production are identified and compared to each other regarding net energy generation, costs and environmental impacts (LCC - Life Cycle Costing and LCA - Life Cycle Assessment). In the assessment of the quantitative outcomes, benefits and drawbacks of different systems can be discovered and the results will be used to support developers of a novel bioreactor and to give suggestions for further research.
Proposals of the agricultural products cultivation system due to Blue Tower gasification combined-cycle systems to reduce CO2 emission
Tokyo University of Science, Japan
Recently, the carbon-footprint on the agricultural products such as vegetables would become attractive. Especially, Ministry of Agriculture, Forestry and Fisheries (MAFF) tries to introduce this scheme by which the consumers have interests in the global warming protection and/or the abatement of CO2 emissions by 2011. In addition, due to the carbon-footprint for agricultural products, the added value for CO2 emission reduction might be brought.
In this paper, we propose the greenhouse system for a paprika cultivation, or the vegetable cultivation factory, in which the required energy would be supplied by the biomass gasification process of Blue-Tower (BT). Also, based on the experimental result on the biomass gasification process, we designed the entire system, and estimated the specific CO2 emission of agricultural products due to LCA methodology.
In our proposal, we obtain electricity and/or thermal energy through the internal combustion engine or fuel cell which would be operated by the syngas fuel. For instance, the integrated BT gasification SOFC (Solid Oxide Fuel Cell) combined cycle might be suitable due to the higher power efficiency. However, the installation cost is still expensive in comparison to the conventional system. The BT gasification cogeneration system of gas-engine has already come into practical use. Although the installation cost of this system is not so expensive, the energy efficiency is lower. Thus, CO2 benefit due to the promotion of this system would be decreased. Here, according to our process designs, the net power efficiency in the case of BT-gas engine system is 16.3 %-LHV, and that of BT-SOFC case is 20.6%-LHV. In the BT-gas engine system; although thermal energy is generated, every amount of the energy is not utilized due to the discrepancy between energy demand and supply.
In the energy demand side, we assume that the environmentally friendly energy supply, that is, the energy of biomass feedstock is altered with the conventional energy of fossil fuel origin. Also, the CO2 gas due to the exhausted gas through the biomass plant would encourage a paprika or a leaf vegetable growth. That is, our system is a tri-generation, and there is potential to reduce the specific CO2 emission of a product due to the alternation of conventional energy and/or the increase of yield amount. In our proposed cases, we would be able to reduce CO2 emission of agricultural products into approximately 60% at a maximum, in comparison to the conventional product.
The importance of dynamic production patterns in assessing the environmental and economic benefits of distributed generation from wind turbines and photovoltaic panels
1CIRAIG-Ecole Polytechnique de Montreal, Canada; 2CIRAIG-HEC Montreal, Canada; 3NCASI, Canada
Distributed generation (DG) from renewable technologies is often proposed as a sustainable solution to reach actual energy policy goals such as reducing greenhouse gas emissions and adding supply to meet increasing energy demand. Previous work modeling the life cycle implications (environmental, economic and energy) of grid-connected photovoltaic panels and micro-wind turbines, showed their potential short-term benefits in the Northeastern American context, as long as oil centralized electricity production is displaced. According to the ISO 14040 standard, environmental and energy implications of these technologies were modeled using Human Health; Ecosystem Quality; Climate Change; Resources and Non-Renewable Energy Payback Ratio indicators. Economic implications were modeled using conventional life cycle costing. However, the presented study does not consider variations in hourly electricity production levels. Indeed, changes in time for the renewable technologies are fundamental and ignoring them could reduce the relevance of the study results. Moreover, when DG renewable technologies are applied, the displaced electricity is not solely produced from one source of energy but more from multiple sources also changing in time.
The objectives of this study are to include an in-depth analysis of the actual electricity production displaced by DG and to assess its life cycle benefits (environmental, economic and energy) by considering dynamic production patterns.
To achieve this objective, an electricity trade analysis is proposed to enhance the accuracy in estimating the displaced electricity and its associated benefits when the investigated DG renewable technologies are applied in the Northeastern American context. First, this approach consists of examining the province of Quebec hourly electricity exchanges with adjacent jurisdictions (New Brunswick, New England, New York and Ontario) over the 2006-2008 period. Fuel costs are calculated and compared to Quebec electricity exchanges to point out the dynamics (hourly) of marginal electricity production technologies. Once identified, the life cycle benefits due to displaced electricity production can be assessed by matching the hourly life cycle implications of marginal electricity production technology with those of the investigated DG renewable technologies
The climate change indicator results bring clear evidence of the usefulness of proposed electricity trade analysis in enhancing the accuracy in estimating electricity displacement and its potential GHG benefit. It is found that greenhouse gases reductions are overestimated by approximately 120% to 200 % when only oil centralized electricity production is considered displaced. Future work will include the other environmental, energy and economic indicators discussed above.
LCM of green food production in Mediterranean cities: Environmental benefits associated to the energy savings in the use stage of Roof Top Greenhouse (RTG) systems. A case study in Barcelona (Catalonia, Spain)
1Universitat Autònoma de Barcelona, Spain; 2Inedit Innovació SL, Spain; 3Institute of Research and Technlology in Agrifood Sector (IRTA), Spain
Cities exert enormous pressure on the natural environment destroying ecosystems, green areas, biodiversity and consuming resources. The current food model is produced and processed through a linear urban metabolism, which involves the use of water, waste, GHG emissions and energy costs during its life cycle greenhouse.
One way possible way for reducing the carbon footprint of cities is integrating agriculture production in them, through urban agriculture systems in buildings, such as roof top greenhouses (RTG). These systems not only approximate the horticultural products to consumer but also increase the thermal isolation of the building.
This study assesses the energy and GEH emissions savings of RTG systems in Mediterranean cities in relation to the current constructions, through a pilot study situated in a catering service building in the city of Barcelona (Spain). The system analysed includes the greenhouse materials and the use stage of the building, focusing on the study of the roof thermal performance and its effects on the building internal climate.
Once the different structural systems and materials of the building and greenhouse were defined, three evaluation scenarios were defined focusing on the energy and materials consumption by means of a comparative Life Cycle Assessment (LCA):
(1) current roof structural system (steel and plywood), (2) conventional isolation (mortar, concrete, polystyrene, air chamber and plywood), and (3) a RTG as an alternative structural system.
For the use stage, the scenarios were modelled in the "DesignBuilder" energy simulation program, which uses the EnergyPlus dynamic simulation process to generate performance data, from climate and thermal characteristics of the materials data.
Preliminary results show that, comparing scenarios 1 and 3, a RTG system represents a saving of 40% in energy consumption of the building, which means 31.000 kWh and 8.57 tonnes of equivalent CO2 in a year
Other indirect benefits of the RTG scenario that will be taken into account in the analysis could be linked with the interconnection of energy and CO2 flows of the RTG with the building itself, leading to further energy savings.
Are catch crops sustainable for biogas production?
Agroscope Reckenholz Tänikon (ART), Switzerland
Catch crops cultivated in autumn or over winter can be used as green manure, forage or co-substrate in biogas production. Farmers have the choice between many single crops and crop mixtures depending on their needs. But which catch crops and catch crop mixtures are preferable, in terms of environmental sustainability, energy-efficiency and profitability?
In order to elaborate recommendations, we studied the life-cycle impacts and economic viability of four catch crop species and four catch crop mixtures. The system comprises cultivation processes from pre-sowing soil preparation up to the production of silage bales, assuming that silage bales are suitable for both storage and sale. Non-renewable energy demand (NRE), global warming potential (GWP) and nitrogen eutrophication potential (NEutro) as well as the full production costs of the cultivation were assessed. Different cropping variants were considered in order to take into account the effects of differing sowing dates, production intensities and fertilisation types (organic and mineral). Emissions and impacts were assessed with the SALCA method – the Swiss Agricultural Life Cycle Assessment, which implements eco-inventories from the ecoinvent database (Swiss Centre for Life Cycle Inventories), and calculation models according to Hischier et al (2009), IPCC 2006 (Guidelines for National Greenhouse Gas Inventories) and EDIP 2003 (Hauschild & Potting 2004) with specific consideration of Swiss soils and climate. Environmental impacts were analysed for four functional units, considering cultivated area (ha), dry matter yield, metabolisable energy (MJ) and potential biogas production (m3).
The recommendability of investigated catch crops differs depending on the impacts analysed. Whereas the most recommendable crops regarding GWP including all functional units are mustard and sunflower in the low- and slurry-fertilised variants, grass-legume-mixtures in the variants without fertilisation and low-mineral fertilisation present the best results for NEutro. For NRE, no catch crop scores best in all analysed functional units, but overwintering, multi-harvested and slurry-fertilized ryegrass and grass-clover mixtures are most recommendable per dry matter and energy yield. Financially, autumnal crops cause lower costs per hectare, but the cultivation of overwintering crops is less costly considering the production of dry matter and energy yield.
In summary, we conclude that catch crops for biogas production need a certain time to develop a useable yield in order to be sustainable, i.e. autumnal crops should be early-sown and if this is not possible, overwintering crops are preferable.
Life cylce assessment for bioethanol production from cassava in Colombia
1GAIA Servicios Ambientales S.A.S., Colombia; 2Politécnico Jaime Isaza Cadavid, Colombia
The bioethanol in Colombia (South America) replace the 8% the national consume for transport and it represents near of 263.340 gallons per day. To build a national guideline for sustainable production and use of biofuels in order to minimize the negative effects and to maximize the positive potential, the government will need to evaluate the prospect with life cycle thinking. Actually Colombia has production of Biodiesel from palm oil and Bioethanol from sugarcane.
A life-cycle energy and environmental assessment was conducted for bioethanol production from cassava in Colombia. The scope covered all stages in the life cycle of bioethanol production including cultivating, chip processing, transportation and bioethanol conversion. The transport and the use of bioethanol in a car were including. The input–output data were collected at plantation sites in Colombia, the ethanol data were collected in a pilot of Bioethanol from cassava and included energy consumption. For the use, the model includes the emission for combustion of bioethanol in a typical car in Colombia.
For the Life Cycle Assessment the Impact Assessment methods used were CML 2000, for eutrophication, acidification, photochemical oxidation, human toxicity, ozone layer depletion, abiotic depletion and IPCC2007 GWP100a for global warming. In the entire life cycle assessment the impacts are important for the use the bioethanol in a car. At the other stages, the ethanol production is important for the environmental impact of the product.
The carbon footprint of the bioethanol from Cassava is 65gCO2e/MJ, while the carbon footprint for conventional gasoline is 82gCO2eq/MJ. The energy conversion efficiency of Fuel ethanol is 1.34, indicating that the energy from ethanol out of these raw materials is higher than the energy supplied during its production.
The Bioethanol from Cassava is an efficient energy option for Colombia, since cultivation don´t requires irrigation and needs lower quantity of fertilizer for its production. Furthermore, the Cassava has a high demand for manual labor and do not compete with food products