Life Cycle Assessment of Greenhouse Gas Emissions From Natural Gas And Biomass Power Plants - Literature review Example

? Life cycle assessment of greenhouse gas emissions from natural gas and biomass power plants November 09, Table of Contents 5 Abstract 5 2. Introduction and Background 5 2. Introduction and Background 5 2.1. Important terms 5 Figure 2.1. Cost of CSS (Azar, et al, 2006) 9 Figure 2.2. Potential for underground carbon storage (Azar, et al, 2006) 9 3. Literature review and previous work 11 3. Literature review and previous work 11 3.1. LCA of Natural Gas 11 Figure 3.1. LCA of natural gas cradle to grave (Fulton, et al, 2011) 13 3.2. LCA of BIO Gas 15 Figure 3.3. Biomass plant with CCS (Carpentieri, et al, 2005) 17 4. Results 17 4. Results 17 Figure 4.1. Cost comparison of different fuels (Sims, et al, 2003) 19 4.1. Suggestion for a new model 19 5. Objectives of the research 21 5. Objectives of the research 21 6. Proposed Methodology 21 6. Proposed Methodology 21 7. Project Schedule 21 7. Project Schedule 21 Figure 7.1. Gantt chart of project activities 23 7. Conclusions 23 7. Conclusions 23 References 25 References 25 1. Abstract This document provides a summary of the proposed research to assesses the development and use of a Life Cycle Assessment to investigate the environmental impact of the employment of natural gas and biomass to generate electricity in power plants. Use of both technologies are analysed with and without inclusion of carbon capture technology. A preliminary examination of the benefits and drawbacks of carbon capture is done. The document also provides the proposed methodology for the research and suggests a schedule for the full dissertation. 2. Introduction and Background Life Cycle Assessment of power plants has become very important, considering the mandatory requirements to reduce emission of green house gases. Power plants in UK use fuels such as natural gas, biomass, coal, oil and nuclear power. This report will focus on natural gas and biomass fuels. A brief review of important terms related to the topic is given below. This is followed by a review of the literature, methodology and the project plan. 2.1. Important terms Some important terms are defined as follows and these will be used in the report extensively. Life Cycle Assessment - LCA is a method used for assessment of a product or process of the environment from the cradle to grave. This means that all stages in the life of the product is assessed. The assessment evaluates the impact of extraction, processing, transportation of the raw material used for processing and fuels along the operation of the plants to the final decommissioning (Mann and Spath, 2011). Green house gases - GHG is the gas that leads to greenhouse effects by absorbing and emitting infrared radiation, leading to the gradual increase in temperature. Main gases that are GHG are water vapour, CO2, Methane, Nitrous Oxide, Ozone and CFC or Chlorofluorocarbons. These are available naturally in the environment but when the percentage is increased beyond the specified limit, it can lead to global warming. The unit used for measurement is in gCO2e/kWhe or grams carbon dioxide equivalent per kilowatt hour equivalent (Weisser, 2010). Carbon capture and storage - CCS is a process used to separate CO2 from industrial and energy related resources. It includes transportation to the storage location and isolating the gas from mixing with the atmosphere. Reduction of emissions of power plants depends on the CO2 capture system used. Cost of CSS is high and as seen in the below figure, it costs 10 USD/ ton of CO2 to transport the captured carbon to 800 kilometres. Smaller volumes cost higher. Hence, sites near to the power plant are preferred (PACE, 2009). Figure 2.1. Cost of CSS (Azar, et al, 2006) Carbon storage needs a lot of effort in identifying the proper site and ensuring that there is no leakage. Please refer to the following figure that gives the potential for underground carbon storage. Figure 2.2. Potential for underground carbon storage (Azar, et al, 2006) Advantages of carbon capture is that it provides a means to control emissions and to be certified for GHG emission compliance. Drawbacks are that it needs resources and extra costs are incurred besides, suitable sites may not be always available (Azar, et al, 2006). 3. Literature review and previous work Given in this section is a brief overview of previous work. LCA of natural gas and biomass, the advantages and disadvantages are given. 3.1. LCA of Natural Gas Natural gas, obtained from crude oil wells and from other areas is one of the popular sources used in power plants. The amount of GHG release from natural gas is about 500 g CO2-eq/kWh. When carbon capture and storage methods are used, GHG is reduced to 245 g CO2-eq/kWh (Odeh and Cockerill, 2008). However, before natural gas is used for power generation, it must be cleaned and processed to remove impurities. Since transport is a problem, it is compressed to form compressed natural gas and sent over small distance using special container trucks. It is also liquefied and compressed into liquefied natural gas and transported across oceans in special container ships. These processes makes natural gas expensive besides increasing the emission spent in transporting fuel. In the case of natural gas plants, GHG arise the most in case of natural gas fuel during the power plant operation and very little CHG is observed during the construction and decommissioning. Certain processes release the maximum gases and these are gas processing, venting wells, pipeline operation and system leakage in transportation and handling. An example is the Sutton Bridge power station, a combined cycle gas turbine in Lincolnshire that generates 5.6 TWh of electricity per year (Hertwich, et al, 2012). Given below is an illustration of the LCA for natural gas. Figure 3.1. LCA of natural gas cradle to grave (Fulton, et al, 2011) There is also transportation of the gas that not only consumes fossil fuel but can also result in leakages. The leakage rate of transmission of natural gas for a distance of 6000 kilometres is 1.4% while leakage in local and regional distribution results in another 2.7% leakage for 1000 kilometres transported. Overall 10% of CNG is lost before the gas reaches the power plant and thus CHG emissions in upstream lines are high (George, 2011). 3.2. LCA of BIO Gas Biomass, one of the oldest forms of power generation uses plants, wood, plant waste and other forms of vegetation and plant products to produce power. It is one of the most widely used energy source in developing nations and the major cause of deforestation and generation of GHG. In power plants, biomass is burnt in a controlled process chamber to generate heat that is converted to electric power or used directly in a process industry. Ethanol is another product used as an additive with fuel such as diesel and in power plants and this form viable method to reduce dependence on diesel (Rhodes and Keith, 2005; Mann and Spath, 2001). Biomass has an emission of 45 g CO2-eq/kWh and this is among the lowest emissions for different fuel types. When carbon capture and storage methods are used, GHG is reduced to less than 18 g CO2-eq/kWh. Thus, it is seen that the overall reduction in GHG emissions is not very high in biomass since the initial value is low. Eleani power station in UK is a good example of a biomass power plant. Straw is the fuel used in this plant and it has a capacity of 38 MW, generating 270 GWh annually while using 200,000 tonnes of biomass each year. The problem is in transporting such a huge amount of straw to the power plant. In this case, straw fields and cereal plants from which the straw was taken were nearby (Perilhon, et al, 2012; Sebastian, et al, 2010). Given below is an illustration of a typical biomass plant with CCS. Figure 3.3. Biomass plant with CCS (Carpentieri, et al, 2005) 4. Results This section gives the results from the literature review and a brief comparison of the two fuels is done to understand the manner in which they perform. CNG is highly commercialised and about 37% of power in the world is generated through CNG. Sufficient stocks are also available and the level of energy security is high (Viebahn, 2007). However, with biomass, the energy security is less and extensive use of wood, barley and maize for production of ethanol can lead to shortage of grain and can impact the food security. Development of transport and logistics technology such as refrigerated trucks and ships, pipelines and dedicated outlets have allowed this fuel to become portable. This means, natural gas mined in Nigeria is transported economically to Europe or even China (Ruether, et al, 2010). This flexibility and ease of use is not possible with biomass. Compressed gas has a much higher GHG emission and more power is consumed in processing and transporting the fuel. Biomass has a much lesser amount of GHG emissions but the fuel cannot be transported economically over longer distance. Hence, it use is only in power plants in the area where plant vegetation and wood is available (Zhou, 2011). Given below is the cost comparison of different fuels with carbon capture. Figure 4.1. Cost comparison of different fuels (Sims, et al, 2003) In the above table, it is seen that For natural gas, generating costs in cents/ kWh is 6.4-8.4 and cost of carbon reduction in $/ ton of carbon avoided in 71-165. For Biomass, the figures are 2.8-7.6 and -92-117. This Biomass is seen to be much cheaper. However, the potential and availability is less for biomass. 4.1. Suggestion for a new model From the previous sections, LCA of natural gas and biomass shows that GHG emissions are still high. Hence, it is proposed that a combined integrated cycle with the use of renewable energy, carbon capture and cogeneration should be used. Where available, biomass can also be used. Use of renewable energy helps to offset carbon emission and will give a tax reduction. Co generation will increase the efficiency since waste heated water and hot flue gas is used for heating. This model will be examined further in the research (ICF, 2013). 5. Objectives of the research Objectives and aims of the research are proposed as follows. Carry out a detailed LCA of natural gas and biogas power plants Selection of UK power stations based on biomass - straw and methane. Analyse the information regarding transportation of raw materials to and from the plant via lorries and pipeline Provide an alternate model for LCA based on these inputs 6. Proposed Methodology It is proposed that a secondary research method will be used. Data of power plants will be obtained from peer reviewed journals, books and from websites of power stations. These will be analysed in detail for the LCA and a suitable alternate model will be proposed. 7. Project Schedule Given below is a Gantt chart that gives the schedule of activities along with the proposed timeline. Figure 7.1. Gantt chart of project activities 7. Conclusions The paper has examined the LCA of natural gas and biomass plants with and without CCS. It is seen that natural gas has much higher emissions and even with CCS, GHG are still high. Biomass has much lower emissions and with CCS, the fuel source is very attractive. However, biomass fuel is difficult to procure and costly to transport in bulk. References Azar. C.; Lindgreen. K., Larson. E., and Mollersten. K., (2006). Carbon capture and storage from fossil fuels and biomass - costs and potential role in stablizing the atmosphere. Climatic Change, 74, pp. 47-79 Carpentieri. M., Corti. A., Lombardi. L., (2005). Life cycle assessment (LCA) of an integrated biomass gasification combined cycle (IBGCC) with CO2 removal. Energy Conversion and Management, 46, pp. 1790-1808 Fulton. M., Mellquist. N., Kitasi. S., and Bluestein. J., (2011). Comparing life cycle greenhouse gas emissions from natural gas and coal. Deutsche Bank AG, Frankfurt am main George. F. C., (2011). Life cycle emissions of natural gas and coal in the power sector. Working Document of the NPC North American Resource Development Study, pp. 1-22 Hertwich. E. G., Aberg. M., Singh. B and Stromman. A. H., (2012). Life-cycle assessment of carbon dioxide capture for enhanced oil recovery. Department of Energy and Process Engineering, Norwegian University of Technology Mann. M. K., and Spath. P. L., (2001). A life cycle assessment of biomass co-firing in a coal fired power plant. Clean Production Processes, 3, pp. 81-91 Odeh. N. A., and Cockerill. T. T., (2008). Life cycle GHG assessment of fossil fuel power plants with carbon capture and storage. Energy Policy, 36, pp. 367-380 PACE, (2009). Life Cycle Assessment of GHG Emissions from LNG and Coal Fired Generation Scenarios: Assumptions and Results. Center for Liquefied Natural Gas, Fairfax, USA Perilhon. C., Alkadee. D., Descombes. G., and Lacoura. S., (2012). Life cycle assessment applied to electricity generation from renewable biomass. Energy Procedia, 18, pp. 165–176 Rhodes. J. S., and Keith. D. W., (2005). Engineering economic analysis of biomass IGCC with carbon capture and storage. Biomass and Bio energy, 29, pp. 440-450 Ruether. J. A., Ramezan. M., Balash. P. C., (2010). Greenhouse Gas Emissions from Coal Gasification Power Generation Systems. U.S. Department of Energy/National Energy Technology Laboratory, USA Sebastian. F., Royo. J., Serra. L., and Gomez. M., (2010). Life Cycle Assessment of Greenhouse Gas Emissions from Biomass Electricity Generation: Co-firing and Biomass Monocombustion. Draft of the paper presented to the 4th Dubrovnik conference on sustainable development of energy water and environment systems, pp. 1-10 Sims. R. E. H., Rogner. H. H., and Gregory. K., (2003). Carbon emission and mitigation cost comparisons between fossil fuel, nuclear and renewable energy resources for electricity generation. Energy Policy, 31, pp. 1315-1326 ICF, (2013). Yukon Power Plant Fuel Life Cycle Analysis: Final Report. Yukon Power Plant Fuel Viebahn. P., (2007). Comparison of Carbon Capture and Storage with Renewable Energy Technologies Regarding Structural, Economic, and Ecological Aspects. ACCSEPT workshop, Bonn, 10-11 May 2007 Weisser. D., (2010). A guide to life-cycle greenhouse gas (GHG) emissions from electric supply technologies. PESS / IAEA, Austria Zhou. J., (2011). Life cycle assessment of greenhouse gas emissions from NAM THEUN 2 Hydroelectric project in Central Laos. Master's Thesis, Master of Environmental Management degree, Duke University, UK Read More