Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation

Transcription

1 Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation February 2013 The information contained in this document is derived from selected public sources. Ballard does not guarantee the accuracy or completeness of the information and nothing shall be construed as a representation of such a guarantee. Ballard accepts no responsibility for any liability arising from use of this document or its contents. Nothing in this document constitutes or should be construed to constitute investment advice. Any opinions presented are subject to change without notice.

2 TABLE OF CONTENTS Biomass-to-Fuel-Cell Power Systems... 2 Feedstock Options... 3 Technology Overview... 3 Emissions and Efficiency Comparison... 5 Case Study: Remote Community... 5 Conclusion... 7 Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation 1

3 Biomass-to-Fuel-Cell Power Systems One of the challenges in siting large scale fuel cell generators is finding a source of low cost hydrogen; hydrogen derived from biomass has the potential to be both an economical and renewable source of fuel for distributed power generation applications. A biomass-to-fuel-cell system offers a renewable source of low emission electricity and heat with flexible feedstock options. Biomass is a fully renewable energy source that is considered greenhouse gas (CO2) neutral and thus can reduce greenhouse gas emissions associated with the generation of power. Biomass - including forestry and agricultural resources, industrial processing residues, municipal solid waste and urban wood residues - is often considered a waste product. Using a gasifier to processes this biomass can create a hydrogen rich syngas which is then purified as a low cost fuel for Ballard s proton exchange membrane (PEM) ClearGen distributed generation system, creating clean energy from this waste. Biomass-to-fuel-cell systems are highly scalable from 200kW to multi-megawatts, offering the ability to size a system to efficiently process the amount of biomass provided. The amount of generally available biomass is not insubstantial. According to a report from Pike Research, worldwide biomass power generation capacity will grow to at least 86 gigawatts (GW) by 2021, from 58 GW in Large scale biomass-to-fuel-cell distributed generation systems can reduce site waste significantly, diverting it from landfills, and potentially reducing the waste streams of neighboring facilities or communities. With a reliable supply of biomass, this system can be used to generate base load, peak power or even emergency power for critical operations in case of power disruptions for durations longer than a few hours. 2 The business case for biomass-to-fuel-cell systems is strongest in regions with high electricity prices and ready access to low cost biomass sources. For instance, the system is a cost competitive alternative today in remote communities relying on diesel generators. Product cost reduction paths will improve opportunities in markets with high industrial electricity rates or financial subsidies for renewable energy sources. 1 Pike Research (2012, January 10). Global Investment in Biomass Power Generation Will Total $104 Billion Through Retrieved July 18, 2012, from 2 Shorter durations or intermittencies can be overcome more cost effectively via batteries. Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation 2

4 FEEDSTOCK OPTIONS Biomass availability for electricity generation varies by region, according to the availability of low cost sources. Biomass that is available locally decreases the need to transport the fuel long distances, improving energy efficiency and reducing the cost of the power produced. Organic waste feedstock options are widely varied, including: Agricultural and forest residues (e.g. wood chips, sawdust) Miscanthus grasses Mixed paper waste Corn stover Trees and tree trimmings, specifically fines, barks, needles, and leaves Animal bedding (straw) Construction wood waste The feedstock is typically processed into small pieces, less than one-quarter inch in diameter. One key advantage of biomass-to-fuel-cell system is that it can handle higher moisture content (up to 45%) than most conventional gasifiers, reducing the need to dry feedstock. The system is robust against trace amounts of common contaminates (including sand, concrete and ammonia) which can often be diluted by pre-mixing cleaner material in with that which is contaminated, or eliminated through low-tech, easy to source sorting machines. However, the system is unable to process certain materials including metals, glass and PVC plastics. TECHNOLOGY OVERVIEW Ballard has established partnerships with developers of biomass gasification technology to demonstrate a complete, industry leading waste to energy renewable power generation system. Figure 1 demonstrates the processes involved in transforming biomass into power with a fuel cell system. The system can be divided into four main components: a) Biomass Handling b) Pyrolysis Gasifier c) Purification d) PEM Fuel Cell System Figure 1: Schematic of a biomass-to-fuel-cell power system Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation 3

5 In the biomass handling subsystem, the raw biomass feedstock is prepared by grinding it into pieces less than one-quarter inch in size. No drying is necessary if the biomass is below 45 percent moisture content. The system is estimated to consume approximately 15 dry tonnes per day of biomass per megawatt of electricity output. This prepared feedstock is then fed into a pyrolysis gasifier, which generates a hydrogenrich gas stream. The gas mixture produced contains approximately 65% hydrogen, 30% carbon dioxide, and 5% other components. This hydrogen rich syngas is then processed through a purification process, to eliminate contaminants from the hydrogen. Separation can be done either through pressure swing absorption (PSA), water gas shift (WGS) or preferential oxidation (PrOx). The result is a high-purity hydrogen stream, which is used to power the fuel cell system, generating clean power and heat. The fuel cell module is connected to a DC/AC inverter to provide high quality power at 50Hz or 60Hz that can be exported to the grid. Additionally, the hydrogen is of high enough quality to provide fuel for fuel cell vehicle fleets. Total biomass-to-fuel-cell system electrical efficiency is approximately percent. This can be increased to as much as percent total efficiency when the waste heat from the fuel cell system is captured and used to heat onsite facilities in cogeneration applications. The system is completely scalable to match biomass availability and energy needs, ranging in power outputs from 200kW to multi-megawatts. A sample system layout with all the major sub systems is shown in Figure 2 for reference. With modular components, layout of the system is highly flexible and can be modified to suit the requirements at the site. The total required footprint for a 200kW plant, including the feedstock system, is approximately 80 x 100. Figure 2: Sample biomass-to-fuel-cell system layout Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation 4

6 EMISSIONS AND EFFICIENCY COMPARISON The biomass-to-fuel-cell system is the best solution for high efficiency, low emission power production. Figures 3 and 4 below compare the biomass-to-fuel-cell system with diesel generation and conventional biomass gasification systems utilizing a gas fired engine for power production. The biomass-to-fuel-cell system offers comparable overall efficiency with greatly reduced nitrous oxides, typically produced during the combustion process. Figure 3: Comparison of system efficiency Figure 4: Comparison of NOx emissions CASE STUDY: REMOTE COMMUNITY The use of biomass as the fuel for these systems may be a very good choice for remote communities, such as those in which forestry activities are significant and wood resources are abundant. A biomass-to-fuel-cell system allows communities to substantially reduce reliance on diesel generators, providing a more economical levelized cost of energy and reducing harmful greenhouse gas emissions. The economics of a biomass-to-fuel-cell power system installed at a remote community are analyzed in the following case study. The technology is compared to a diesel generator, on the basis of capital cost, operating cost and, ultimately, total cost of ownership over a 20 year period. The payback period for the biomass-to-fuel-cell power solution relative to the incumbent KEY CASE STUDY ASSUMPTIONS: technology is computed. System size 500 kwe net For the purposes of this hypothetical Availability 95% case study, both the diesel generator and biomass-to-fuel-cell system are Product lifetime 20 years sized to produce 500 kilowatts net, Diesel fuel costs US$1.50/L each operating at an efficiency of 35 percent. The biomass-to-fuel-cell Biomass feedstock costs US$30/tonne power plant cost is estimated at US$4.5 million, including pyrolysis Discount rate 10% Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation 5

7 gasification, gas purification and installation. The diesel generator cost is estimated at US$100,000 including installation. The cost of the biomass feedstock, fully prepared for use in the pyrolysis system is estimated to be US$30 per tonne, while the diesel is priced at a cost of US$1.50 per litre, delivered. Figure 5 shows the cumulative cash flow of a 500kW biomass-to-fuel-cell power system compared to a standard diesel generator. Results show that the biomass-to-fuel-cell power system payback is achieved in approximately three years, with an IRR of 34%. Biomass to Fuel Cell Power vs Diesel Generator $30,000 Cumulative Cash Flow (US$ '000) $25,000 $20,000 $15,000 $10,000 $5,000 $0 -$5,000 Payback achieved in ~3 years Years IRR: 34% NPV: US$5 million Figure 5: Cumulative Cash Flow The current levelized cost for a biomass-to-fuel-cell power system is approximately US$0.20 per kilowatt hour, making it competitive as an alternative to diesel generators in remote communities. In some regions, where biomass sources are plentiful, the cost of biomass is low enough to drive an even shorter payback period. There are also opportunities to further improve on this business case through the additional savings associated with waste heat utilization. Heat generated by the plant can be captured and used as an energy source for buildings or district heating systems, providing further emissions reduction benefits through offsetting combustion of natural gas or cost reduction in the case of electrical heat. And, an additional potential revenue stream can be realized through the sale of biochar, a by-product of the pyrolysis system used as a soil supplement. Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation 6

8 CONCLUSION A compelling value proposition for distributed power generation is the conversion of waste biomass to energy. A biomass-to-fuel-cell system offers a renewable source of low emission electricity and heat with flexible feedstock options. The system will process biomass using pyrolysis gasification to create hydrogen rich syngas which can be purified for use with Ballard s ClearGen PEM fuel cell system. Ballard is now pursuing further installation opportunities to develop biomass to energy systems based on ClearGen fuel cell technology. The system is cost competitive in remote communities today, as a clean, quiet and efficient alternative to diesel generators. Future cost reduction paths will enable the solution to be sited wherever relatively high electricity prices and low cost biomass are available. Biomass-to-Fuel-Cell Power For Renewable Distributed Power Generation 7