NOMBRES Y APELLIDOS:
INFORME DE SESION DE ECA Nª 03
Floor Area - Existing - New - Total 3.1 million sq ft 1.4 million sq ft 4.5 million sq ft 1.6 million sq ft 2.4 million sq ft 4 million sq ft Use Mix 80/12/8 Residential/Office/Retail 10/15/5/30/40 Residential/Office/Retail/Hotel/Event Annual Heating 39,000 MW.h 30,500 MW.h Annual Cooling 16,500 MW.h 21,500 MW.h
Peak Heating Demand (Diversified) 11 MW 12.5 MW
Peak Cooling Demand (Diversified) 18 MW 16.5 MW
Potential GHG Reductions with District Energy (tons / year)
1. Gas boilers and electric chillers w/ waste heat recovery from cooling 2. Natural gas cogeneration 3. Biomass heating 4. Cogeneration w/ 60% biogas 3,700 6,600 8,600 13,800 3,300 6,000 7,700 12,500
On-Site Boiler and Chiller Space Requirements
16 to 20 thousand sq ft 14.5 to 18 thousand sq ft District Energy Center Footprint
(depends upon technology)
10 to 13 thousand sq ft 9 to 12 thousand sq ft
System Capital Costs $40 – 50 million N/A
Cost-Effectiveness Competitive with business-
as-usual heating costs on a lifecycle basis
To be determined
The North Pearl District Energy Study considered a wide range of energy sources, many of which could also apply to the Rose Quarter / Convention District. Four systems were examined in a more detailed analysis: 1) central natural gas boilers and electric chillers, with waste heat recovery and storage from cooling; 2) biomass heating only (with partial reliance on steam chillers for cooling); 3) natural gas cogeneration; and 4) cogeneration with 60% biogas input (from a local anaerobic digestion facility for trucked liquid waste). The Phase 1 capital costs from the North Pearl District Energy Study were $40 to $50 million, depending upon the technology configuration. This includes the cost of the energy center, distribution system, and energy transfer stations. About 40% of these
system costs are associated with distribution and the energy transfer stations. Distribution costs will vary from site to site depending upon the unique distribution requirements (load density, spacing, relative location of energy center to load, etc.). There was insufficient information or resources to develop a representative layout and cost for distribution at this site. The layout and costs will also depend on the desired site for the energy center. There are several candidate locations for an energy center in this node. Depending upon the technology, an energy center could be co-located within a building or redevelopment site. A stand-alone site may also be possible in the
northwest area of this node, or adjacent to or under I-5. A location under I-5 is quite central to loads and could be a good use of land that is of low value for other uses. However, this location would require an agreement with the Oregon Department of Transportation.
The cost of energy transfer stations will also depend in part on the number and size of stations required. There are economies of scale associated with energy transfer stations and there would be fewer and larger energy transfer stations in the Rose Quarter / Convention District node.
In the North Pearl District Energy Study, district energy was competitive with business- as-usual lifecycle heating and cooling costs. That is, the lifecycle cost of district energy was comparable to the lifecycle costs of on-site energy, taking into account all capital, maintenance, fuel and other operating costs, including a target return on investment, including debt and equity. This was based on a system covering the entire study area. A sensitivity test using Phase 1 loads only suggested the system would be competitive using a 100% debt financing model. However, the sensitivity analysis did not include any further optimization of capital that may be possible if target loads were smaller (e.g., reducing the sizing of piping to exclude future growth potential). A full feasibility analysis of the Rose Quarter / Convention District node would be required to establish the economics of district energy specific to this node.
In addition to financial viability, the North Pearl Study also considered GHG emission reductions from district energy. Emission reductions relative to business-as-usual were significant, ranging from 3,700 tons per year for the waste heat recovery alternative to nearly 14,000 tons per year from cogeneration with biogas, a 30% to 115% reduction relative to business-as-usual emissions for heating and cooling. The cogeneration alternatives assumed all electrical output in excess of the electric chiller requirements was sold to the local electric utility and included a GHG credit for avoided electric system emissions. Prorated for floor area, the emission reductions from comparable systems for the Rose Quarter / Convention District node would range from 3,300 to 13,500 tons per year, assuming similar technology alternatives.
It is useful to contrast these potential GHG reductions from district at the Rose Quarter / Convention District node with other recent energy proposals for the Lloyd Pilot
EcoDistrict. One of the recommended showcase projects in the recent Declaration of Cooperation for the Lloyd Pilot EcoDistrict was to explore renewable energy potential and GHG emission reductions through a district-wide rooftop solar PV program. A
report was also recently prepared to assess the feasibility of solar PV and solar thermal on the Memorial Coliseum.19 The Memorial Coliseum provides a great opportunity for a large solar energy application on its roof given the lack of roof-mounted equipment and shading from adjacent structures. The feasibility report considered technology options, sizing, technical feasibility, and capital costs. A full economic (lifecycle) and GHG analysis was not included in the analysis.
Table 6 provides a preliminary assessment of the solar energy potential, GHG reduction, and costs based on the Coliseum study and production data from other comparable systems. The analysis in Table 6 is conservative in that we have used the most favorable assumptions in ranges. For example, we have used the lowest system capital cost assumptions (before incentives). We have also not included any ongoing operations or maintenance costs for solar systems. Lifecycle costs are estimated using a 10% discount rate. The range in lifecycle costs reflects different system life assumptions. We used 15 to 25 years for solar hot water systems and 20 to 40 years for solar PV systems. For output, we assumed a capacity factor of 12% for solar PV and an average annual output for solar hot water of 35 kW.h/sq ft of collector area.
The Memorial Coliseum Solar Feasibility Report suggests that about 20,000 sq ft of rooftop area could be available for solar PV panels.20 In the case of solar hot water, the report recommends a system covering approximately 2,000 sq ft. We assume this was based on the available summertime hot water loads, which are more limiting. We note that in the case of a district energy system there may be some opportunity to share excess heat from a larger system located on the coliseum. However, structural (weight) limits may also limit the maximum size of the solar thermal system to something less than the maximum potential for solar PV.
For solar PV, we have assumed a levelized retail cost of electricity of $95 / MW.h. For solar hot water, the avoided costs assume a levelized cost of natural gas of about $53/MW.h, adjusted for a typical boiler efficiency of 80%. We assume neither system would avoid significant capital costs (electrical capacity or boiler capacity costs). GHG emission reductions are based on average emission factors for electricity (in the case of solar PV) and natural gas (in the case of solar hot water). We estimate a net cost (savings) for avoided GHG emissions based on the lifecycle cost premium for each system divided by the annual GHG savings. We estimate the premium for each system both without any incentives and after a 50% capital credit.
19
Glumac. April, 2010. Memorial Coliseum Solar Feasibility Report. Prepared for National Renewable Energy Laboratory. Available at:
http://rosequarterdevelopment.org/files/rq_mc_solar_feasibility.pdf
20
More area would be available for thin film technology but the output and lifecycle cost is approximately equal to panels adjusting for efficiency and relative unit costs.
Table 6: Solar Assessment for Memorial Coliseum Technology
PV Solar Thermal
Surface Area 20,000 sq ft 2,000 sq ft
Capacity 380 kW N/A
Capital Cost (No incentives)
$2.8 million $46k Annual Useful
Energy Output
400 MW.h 70 MW.h
Lifecycle Cost (No incentives) $730-840/MW.h $70–85/MW.h Avoided Cost $95/MW.h $50–55/MW.h Annual GHG Reductions 177 tons 16 tons Premium (No Incentives) Net cost of $1,400–1,700/ton Net cost of $80-140/ton Premium (50% capital incentive) Net cost of $600-750/ton Net benefit of $10-15/ton
The analysis suggests that the GHG savings from a solar system on the Coliseum roof are a fraction of the potential savings associated with a larger district energy system. The difference depends upon the ultimate district energy technology selected. Solar PV has a much higher premium per unit of energy produced and per unit of GHG savings. Solar thermal could in fact have net cost savings or a negative cost per ton of GHG reduction assuming a 50% capital incentive. It is not clear whether this magnitude of incentives would be available for solar thermal systems. In addition, the contribution from solar thermal is limited by the available summer heat loads. Assuming sufficient summer loads, it would take about 400,000 sq ft of thermal collectors (roughly 14,000 MW.h or 20% of the current total heating load in the Lloyd Pilot EcoDistrict) to achieve a GHG reduction of 3,300 tones, which is roughly equivalent to the lowest estimated GHG reductions from a district energy system in the Rose Quarter / Convention District using waste heat recovery technology.
A district energy system could enhance the value of solar thermal at the Coliseum. A larger district energy system would allow solar thermal to be oversized relative to on- site loads. Waste heat could be rejected back to the district energy system to be shared with other users. There are economies of scale associated with solar thermal systems so this approach could reduce any premium for solar thermal. Environmental benefits would depend upon the type of energy that was being displaced in the district system (e.g., natural gas boilers vs. other alternative energy sources). Lonsdale Energy
Corporation in North Vancouver, BC has installed a large solar array on a public library to provide heat for their gas-fired district energy system. Three buildings in Vancouver’s Southeast False Creek district energy system have also installed solar thermal collectors. They reject excess heat in summer to the larger district system and receive a heat credit
on their bill. This has turned out to be the most cost-effective strategy for achieving their target of net zero annual energy consumption.
There are several other potential value-added opportunities for district energy in the Rose Quarter / Convention District node. Many existing and proposed developments will have requirements for back-up generators. A cogeneration-based heat source could be leveraged to reduce back-up generator capacity, either by co-locating the energy center at a site with large back-up requirements or by creating a microgrid to share back-up capacity among several buildings. It may be possible to leverage additional value from cogeneration by proactively attracting other large, power sensitive loads to locate within this node (e.g., a data center).
District energy may also provide local peak load reduction opportunities through the addition of thermal storage for cooling. Thermal storage allows for the production of chilled water (or ice) during off-peak periods for use in peak periods. Larger systems may be more cost-effective than individual (building scale) storage systems. The district energy system could also provide an alternative platform for dealing with local food wastes. There are currently about 3,000 tons of food waste produced annually within the Lloyd Pilot EcoDistrict alone. This could grow to as much as 5,000 tons by 2035. A lot of food waste is generated by event spaces within the Rose Quarter / Convention District Node. Other food waste would also be available outside of this Pilot EcoDistrict. One of the recommended showcase projects in the Declaration of Cooperation for the Lloyd Pilot EcoDistrict is to create a district-scale food waste compost program.21 It is not clear whether this initiative contemplates the possibility of anaerobic digestion.
Generally, the term composting is used to refer to aerobic composting. Anaerobic Digestion (AD) is a form of composting that also involves energy recovery. Specifically, AD is a process whereby organic waste is broken down in a controlled, oxygen free environment by bacteria naturally occurring in the waste material. The process produces biogas (primarily methane), which can be used to produce heat and/or electricity. The residual nutrient rich liquor and digestate is suitable for use as fertilizer.22 Recent studies suggest anaerobic digestion could have environmental and economic benefits over landfilling or composting in the right applications.
21
The Riker's Island Correctional Facility in New York City has an on-site composting system that processes about 5,000 tons per year, roughly equivalent to the projected future food waste generation rates for the Lloyd EcoDistrict.
22
An excellent overview of AD technologies, precedents and issues can be found in a 2008 report prepared for the California Integrated Waste Management Board entitled “Current Anaerobic Digestion Technologies Used for Treatment of Municipal Organic Solid Waste.” The report can be found at http://www.calrecycle.ca.gov/publications/Organics/2008011.pdf. AD is currently more common in Europe where waste management policies, tipping fees and renewable energy policies all promote AD. Larger systems are more common and cost-effective, but there are examples of
Alternatively, food waste disposal could also be integrated into a local wastewater treatment project. Many wastewater treatment plants already use AD to convert the incoming organic waste and/or wastewater treatment sludge to energy. If wastewater digesters are oversized or underutilized, systems could theoretically, with some modifications, be used to treat food waste. The East Bay Municipal Utility District in Northern California is currently investigating the incorporation of food waste into its wastewater treatment sludge digesters.
There are other potential synergies between district energy and local wastewater treatment. For example, one source of energy for a district system could be waste heat recovered from treated effluent. Waste heat recovery from wastewater treatment was recently implemented for the Olympic Village in Whistler, BC.23
There are other possible linkages between district energy and water management. For example, a central cooling system would offer a more convenient and potentially cost- effective reuse opportunity for effluent from a local wastewater treatment system, compared to distributed cooling. The floor area in the screening analysis could require up to 11 million gallons of water annually for cooling.
The screening analysis suggests potential feasibility and value for a district energy system in the Rose Quarter / Convention District node. The following scope and methodology is recommended for the full feasibility study:
Establish initial boundaries (target parcels) for the core system to facilitate evaluation, with one or two expansion scenarios (additional parcels) to understand effects of scale (cost, performance, ability to expand, etc.). Confirm new development floor areas and use mix. Establish a likely sequencing (base case) to support preliminary design and phasing analysis. Confirm baseline heating and cooling requirements (end use) and equipment efficiencies for existing buildings (taking into account likely building efficiency upgrades during redevelopment) and for new construction.
Confirm compatibility of existing event spaces with district energy and cost of any retrofits required. Confirm age of existing equipment and likely timing of replacement for use in avoided cost calculations (preliminary utility revenue assumptions).
smaller systems comparable in size to the Lloyd. For example, a facility installed in 2007 in Central Bedfordshire Council in England facility by Biogen Greenfinch treats roughly 5,000 tons per year of food waste.
23
This should not be confused with sewer heat recovery at Southeast False Creek, which recovers heat directly from raw sewage at a local pump station.
Confirm avoided capital, fuel and maintenance costs for new construction for use in avoided cost calculations (utility revenue assumptions).
Establish demand profiles (average vs peak; monthly profiles) for different heating and cooling loads. These may affect optimal sizing and expected performance of systems.
Establish a potential energy center location for purposes of developing preliminary distribution layout, phasing and costs. Confirm site has sufficient space and access for proposed technology solutions. Identify an alternate site for possible sensitivity analysis.
Establish number, size, cost and likely locations of energy transfer stations. Establish preliminary distribution layout.
Develop several technology configurations, including phasing options for technology. Based on the outcomes in the North Pearl, consider at least four options:
o Natural gas boilers and electric chillers with waste heat recovery and short-term thermal energy storage.
o Biomass-fired boilers and steam chillers, with natural gas boilers and electric chillers for peaking.
o Natural gas cogeneration with electric chillers and short-term thermal energy storage.
o Natural gas cogeneration with electric chillers and short-term thermal energy storage, but displace a portion of natural gas with biogas. The biogas could come from an on-site wastewater treatment plant or anaerobic food waste digestion or some combination of biogas strategies.
If local wastewater treatment is being considered then waste heat recovery from treated effluent may also become an option.
Develop a pro forma to evaluate financial feasibility. Pro forma should allow assessment of alternate ownership assumptions (capital structures, cost of capital, and taxation).
Identify and characterize (with quantification as possible) environmental impacts (positive and negative) including but not limited to impacts on GHG, energy, etc. relative to baseline.
Identify and evaluate key risks and uncertainties affecting costs or benefits, and possible mitigation strategies / implications for business case.
Identify possible contributions to Portland’s economic development strategy (direct job creation; technology and process demonstration or innovation that could be leveraged into attracting firms and promoting exports).
Identify possible value-added strategies and their potential effects on business case – e.g., potential linkages to Portland food waste management strategies, potable water savings from reuse of treated water in central cooling plant, electric reliability (e.g., microgrid) benefits with cogeneration.
Identify future growth options and strategies, if relevant (e.g., technical expandability, oversizing or other ways to facilitate additional growth). Identify key regulatory or implementation issues and strategies. Some key issues will likely include the following:
o Coordination of land owners
o LEED points that may be available for district energy
o Plant siting and permitting issues
Evaluate ownership, governance and financing strategies to determine the best model given the unique circumstances of this application. These are best dealt with only after technical and economic viability (net social benefit) has been demonstrated. Evaluation should consider the best sources and forms of funding, including contributions from local owners (via development charges, connection fees and/or ongoing user fees), contributions from utilities (e.g., electric system benefits from cogeneration), contributions from City (where costs exceed user benefits but systems provide broader public benefits), and grants or low cost financing from senior levels of government.
Process should ideally involve a technical and economic steering committee composed of:
o Large landowners o PDC
o BES (including representative from Green Streets initiative) o PWB
o Portland Bureau of Planning and Sustainability
o Metro solid waste officials (possible links to food waste) o PBOT and ODOT (use of transportation rights of way) o PoSI and Pilot EcoDistrict stakeholders