Replace natural gas with renewable low carbon biomass pellets - DOC

Document Sample
Replace natural gas with renewable low carbon biomass pellets - DOC Powered By Docstoc
					            Alternative Energy                              X      contest
Team members: UBC Biomass and Bioenergy Research Group
Faculty Names: Dr. Shahab Sokhansanj, Dr. Xiaotao Bi, Dr. Jim Lim, Dr. Anthony Lau, Dr.
Taraneh Sowlati, Staffan Melin
Student Name: Wilson Lam, Saeed Ghafghazi, Zahra Tooyserkani, Ladan Jafari-Naimi, Fahimeh
Yazdanpanah, Ehsan Oveisi, Wendi Guo, Jianghong Peng, Mahmoud Ebadian, Mahidi Mobini,
Ann Pa, Isaac Lam.

Brief background

The UBC Utilities is a multifunctional organization located on the main Campus at the Point
Grey. The Utilities is responsible for acquisition and supplying power, heat, water, sewer system
and maintenance. The Utilities supports itself through at a charge at cost to core academics and a
charge at market price to non academic facilities. The total capital cost of Utilities is estimated
at $350 million.

The Utilities produces approximately 375,000 metric ton of steam annually for in-house use.
Roughly 900,000 GJ/y of natural gas generates steam with roughly 20% of heat load comes from
burning heating oil. The amount of CO2 produced from this steam producing activity is about
60,000 metric ton per year. The capital in steam generation and distribution is estimated at $30
million or roughly 8% of the total capital in total utility infrastructure.

Based on EPA emission factors, Carbon Dioxide emission factor for natural gas is 1.92 tonne/
1000 m3 of total input natural gas. Natural gas average heating value is 10.695 MWh/1000 m3,
that is, each MWh of input natural gas would produce 0.18 tonne Carbon Dioxide.

The UBC Utilities intends to reduce emissions from its operations. To this end, the Utilities is
exploring feasible ideas and seeking advice from the academic and research community.

Proposed solution

The students and faculty of the Biomass & Bioenergy Research Group (BBRG) of the UBC’s
Clean Energy Center proposes that UBC Utilities to design and install biomass burners in the
present boiler house to provide the base heat load for steam production. BBRG also proposes that
the potential of a dual purpose of biomass for combined heat and power to be investigated. Wood
pellets will replace roughly 40% of natural gas on an annual basis. Wood pellets are renewable
and theoretically carbon neutral. A recent study (Chen et. al 2008) on UBC Boiler indicates a
decrease in CO2 emissions by 94% and CO by 25% when wood pellets replace natural gas. An
IEA-Task 38 study (Bradley 2007) also found that wood pellets reduces emissions from a heat
and power plant by 1.3 t CO2/MWh compared to fossil fuels. Considering wood pellets to be
Carbon Dioxide neutral and their net calorific value to be 5.28 MWh/tonne, each 1000 m 3 of
natural gas replaced by the equivalent amount of wood pellets in terms of energy content, would
omit 3.89 tonnes of CO2.
Figure 1: A typical biomass gasification plant to produce combined heat and power (Williams et al.,
1996)


How should UBC reduce overall campus energy and water demand i.e.: electricity, natural gas,
and water consumption. (35 points).

   While converting combustion heat to generate steam might have a thermal efficiency of 50%,
   generating electricity alone from combustion is at best 30% efficient. When heat and power
   are combined, the thermal efficiency may reach as high as 75%. Roughly for every unit of
   electricity twice as much as heat energy becomes available that can be used for heating
   purposes. Although steam generation is the commercial norm of producing steam and power
   but new gasification systems (e.g. Nexterra) are becoming a reliable means of extending the
   efficiency of combusting biomass. We propose that a detailed analysis of using a state of the
   art gasifier for direct power production to be investigated as well. Figure 1 shows a typical
   biomass gasification plant to produce heat and power.

   Chen et al. (2008) reported that it would be more economical to size the gaisifcation system
   for partial implementation for replacing natural gas by wood pellet as fuel for UBC power
   plant in the initial stage. That means wood pellet would only be used to supply a fraction of
   the energy required to generate the steam needed for sufficient heating. The biomass
   gasification system is to be retro-fitted into the natural gas boilers which run the existing UBC
   heating system. Wood pellets will be used to generate syngas in the gasifiers, which will then be
   combusted in the existing boilers to generate steam.

Discuss how your proposal will minimize the disruption to UBC building users. (20 points)

   Replacing base load at UBC power plant will have zero effect on heat and power distribution
   system. While constructing the wood pellet base- load system, the peaking/ backup system
   which is currently operating will be able to maintain the energy production requirements.
   After completion, the base- load system would be connected to the distribution network.

Describe how your project will pay for itself and /or generate, a net positive cash flow from
energy savings i.e. pays for the project implementation, planning, design, construction. Make
specific reference to anticipated avoided annual costs such as reduced carbon penalties, natural
gas purchases or operation/maintenance requirements. (20 points)

   Installing a new wood pellet burning system to serve base-load demand of the UBC plant
   would have some investment cost burden. But it is known that the savings occurred due to
   reduced fuel cost and omitted GHG penalties will offset the initial cost very well. A recent
   study by our group for the Vancouver Olympic Village, suggests $ 4.3 Million of initial costs
   for a 2.5 MW newly constructed wood pellet burning plant. This cost estimate includes land,
   building, equipments, design and engineering, and installations costs. This study shows that
   regardless of the energy sales which would be the same for any system, the reduced O&M
   costs due to replacing the base- load natural gas requirement with wood pellets would have
   on average 22 CAD/MWh of savings for the plant over 25 years service life. Moreover,
   considering a GHG emission penalty of $30/tonne by 2012, as is proposed in:
   http://www.sbr.gov.bc.ca/documents_library/notices/British_Columbia_Carbon_Tax.pdf, the
   natural gas system would have an extra 5.4 CAD/ MWh cost burden compared to almost
   GHG neutral wood pellet system (each MWh natural gas burned would produce 0.18 tonne
   of Carbon Dioxide). This means that the O&M savings of a wood pellet base- load system
   over a natural gas system can be as high as about 27 CAD/ MWh. An average of 18,000
   MWh of heat energy can be produced by the base- load system per year. From the O&M
   savings point of view only, this means a simple payback period of about 9 years while over
   25 years service life, the savings can be as high as $12 million.

   The investment would be roughly $50k/MW biomass boiler. 1 t/h of pellets produce 5 MWh
   of energy. A tonne of biomass offsets 20 t of carbon when using natural gas to produce 5
   MWh. This savings from reduction in carbon will more than offset the extra capital and
   operating costs.

   Chen et al. (2008) carried out a preliminary economic analysis showed that implementation of the
   new system which utilizes wood pellets and natural gas for the production of steam generates an
   annual saving of approximately $2 million. Different valuation methods show that using wood
   pellets is an improvement over natural gas.
Describe how your proposed system will be adaptable to emerging energy distribution trends. i.e.
Efficiency of integration from waste heat sources and alternative energy demonstration projects.
(10 points)

   The use of wood pellets with the installed biomass boilers would help to produce steam and
   electricity to supply to the whole UBC area. Synthesis gas is produced from wood pellets in a
   low-oxygen pyrolysis process. The gas is then reformed in the gasifier into a mixture of
   carbon monoxide, hydrogen and methane and followed by combusting with air in order to
   raise the temperature of the gas. The hot gas is fed into a boiler to generate steam. The
   efficiency of the system is assumed to be 85%. Wood pellets have an average calorific value of
   18 GJ/tonne, and in order to produce 900,000 GJ/year delivered steam, about 60,000 tonnes of
   wood pellets are needed every year.

UBC aspires to be a net positive energy and water campus. Explain how your proposal moves us
toward this goal by minimizing the use of off-campus solutions to environmental challenges. (10
points)

   UBC has the best energy and environmental engineers and scientists. The proposed project
   will make partners between the campus technical services and research/education efforts.
   One of the typical example is UBC biomass and bioenergy research group. The team consists
   of professors, graduate students, research engineers from various department and faculty.
   Moreover, the group has established a strong collaboration and work closely with partners
   from industries and government like Wood pellet association of Canada (WPAC), Ferric,
   Paparican and Natural Resources of Canada. Their expertise can provide consultation to the
   UBC utilities for the boiler installation and supply logistic of wood pellet fuel. This will help
   UBC to minimize the use of off-campus solutions to environmental challenges.

Describe how your proposal provides sustainability and alternative energy teaching, learning and
research opportunities to the UBC community. (15 points)

   Biomass densification and pelletization is a major current research and education at the
   UBC’s Clean Energy Center. The proposed biomass boilers will become a valuable
   opportunity for students and professors to interface with advanced biomass utilization.
   Laboratory practices will be designed for students to take operational and design data and
   conduct calculations and analysis. The students will learn the characteristics of a real system
   and thus are better prepared to support the development of a greener energy for Canada.
   Moreover, the Chemical and Biological Engineering department has offered the first green
   engineering class in Canada taught by Prof. Xiaotao Bi and such proposed project would be a
   real case for students to carry out emission and environmental impact studies. In fact, Chen et
   al. (2008) investigated the feasibility of replacing the natural gas with wood pellet as fuel for
   UBC power plant to reduce the green house gas emissions. On going work can be done by
   other feasibility studies by other students in the class and UBC can benefit from the research
   findings from the class.

Describe how your proposal minimizes negative off campus externalities. i.e. "fuel switching
externalities" such as increased road repair cost resulting from increased trucking or addition of
new off-campus electric generation, etc. (10 points)
   BC is a major producer of wood pellets with over 1 million tones production capacity.
   Currently, over 60% of this amount is shipped overseas and provincial government intensives
   promote the domestic use for this product. Therefore, consuming wood pellets at UBC’s
   plant would not put any negative effect on off campus externalities.

   Fiberco., located in North Vancouver, is one of wood pellet export terminals. The required
   wood pellets can be supplied from this point which is only 20 Kms away from UBC. Trucks
   can carry a payload of about 40 Tonnes of wood pellets. For a 2.5 MW base- load system
   about 5000 tonnes/yr of wood pellets is required. This means that roughly 2 trucks per week
   are required to haul in the wood pellets to the plant.

Use specific examples to demonstrate how your system is "proven" to be efficient at the scale of
the UBC application. If no examples are known, please present compelling evidence for why you
think your vision can work for the UBC campus. (30 points)

   A recent calculation of the produced heat cost for the Vancouver Olympic village, completed
   by our group, shows superior financial performance of a wood pellet burning system
   compared to a natural gas system over the service life of the heating plant. For the considered
   case, financial performance of a 2.5 MW base- load system was studied over 25 years of its
   service life. The initial and O&M costs of a wood pellet system would have been 5.28 CAD/
   MWh and 8.83 CAD/ MWh respectively; While, based on the current trend of the natural gas
   price observed from Terasen Gas, the initial and O&M costs of a natural gas system would
   have been 1.20 CAD/ MWh and 30.85 CAD/ MWh in that order (fuel costs include in the
   operating and maintenance cost). These numbers clearly show that the higher initial costs of
   installing a wood pellet burning system would be offset by its reduced O&M costs over the
   service life of the system. In conclusion, the reduced O&M costs of a base- load wood pellet
   system will offset the initial investment requirements and will also produce positive savings
   for UBC plant. Therefore, from a financial point of view this proposal is an efficient one.
   From a technological efficiency view point, wood pellet burning systems are well proven
   technologies with applications as low as few KW in wood stoves to over 100 MW in biomass
   power plants.
   There are a number of proven district heating plants utilizing wood in BC. In Revelstoke, the
   Revelstoke Community Energy Corporation utilizes a 1.5 MW wood fired boiler for base-
   load and 1.75 MW backup propane boiler. In Victoria’s Dockside Green a wood gasifier
   system is installed to cover the base- load demand of the district heating center. Also, UNBC
   has chosen the same wood gasifying technology to provide the base- load energy of its
   heating plant.
   From environmental point of view, wood and biomass burning is theoretically known to have
   zero net CO2 effect on the climate. This well justifies the environmental efficiency of wood
   pellet burning system compared to that of natural gas boiler.

Considerate of emerging industry technology and approaches to energy production and
management. i.e. GHG neutral energy sources and waste utilization. (10 points)
   The proposed project will be the flagship of other bioenergy and renewable energy projects
   on campus. The production of wood pellets is already a mature industry in British Columbia.
   Industry has produced over 500,000 tonnes of pellets and exported about 90 per cent of this
   product overseas in 2005, primarily to the European thermal power industry. For biomass
   gasification, Nexterra Corporation is a leading company in biomass gasification technology
   and could provide technical consultant to UBC for boiler installation. Moreover, BC Hydro
   also called for a proposal through BC Energy Plan in 2008 for using mountain pine beetle-
   infested timber and wood residue for electricity generation. UBC should consider shifting to
   use latest green technology for power generation.

Describe how your project will be functional, reliable, maintainable and sustainable. (5 points)

   The proposed project has been implemented on at least 50 university campuses in Sweden
   and at least 5 campuses in the U.S. growing. University of UNBC has installed a pellet
   burner-gasifier-boiler system.

Low Grade Vs. High Grade heating; Most buildings on UBC's campus utilize a steam heat
exchanger to convert steam to hot water which is then used to heat the building. The actual
temperature of the heating water supply (HWS) is dependent on the outdoor air temperature. For
an average building on an average day the HWS is 62 degrees Celsius but can reach 90 degrees
Celsius during the coldest days of winter. Knowing this how will your vision overcome the high
grade heating dilemma? (20 points)

   Pellets have a heating value of 20 GJ/t or 15 GJ/m3 based on a bulk density of 750 kg/m3. the
   flame temperature when biomass is combusted is about 1600oC. With this intense heat pellets
   are considered a source of high grade heat.

   Low grade heat conversion technology consideration: we can consider using some low cost
   thermally powered pump, for a number of energy saving, water saving and humanitarian
   applications. These include solar powered water pumps, for sanitation and irrigation, and
   embedded pumps such as central heating water circulators which use waste heat as an energy
   source developed by Thermofluidics Ltd..


   References:

   Chan Bernard, Brian Chan, Christopher Young. 2008. Wood Pellets for UBC Boilers
   Replacing Natural Gas: http://www.aashe.org/documents/resources/Chan_et_al2008.pdf

   The BC Bioenergy plan: A vision for clean energy leadership:
   http://www.energyplan.gov.bc.ca/bcep/default.aspx?hash=6

   Williams R. H., Larson E. D. 1996. Biomass gasifier gas turbine power generating
   technology. Biomass and Bioenergy 10(2): 149-166