Deep Blue Collection: Natural Resources and Environment, School of (SNRE)

Examining the Benefits of Optimal Spatial Diversification of Wind Capacity

Sat, 01 Aug 2009 00:00:00 GMT

Title: Examining the Benefits of Optimal Spatial Diversification of Wind Capacity

Authors: Sadeghi Baghorskhi, Sina

Abstract: This study examines the benefits of optimal spatial diversification of wind capacity as an optionto reduce wind curtailment and, therefore, to increase the utilization of wind capacity. Windgeneration concentrated at sites with the highest energy capture, once aggregated, does notutilize the installed wind capacity at the highest possible rate due to wind curtailment. Contraryto the expectations, wind generation at sites with lower energy capture but with wind generationpatterns that minimize wind curtailment results in a higher utilization of installed wind capacity.Such a configuration requires an optimization scheme to model power system flexibility andwind generation and to allocate capacity with the objective of maximizing the utilization of windcapacity, defined by the term “effective capacity factor”, CFE, (i.e. average system wide windgeneration less curtailment, divided by installed capacity.)In order to measure the benefits of optimal spatial configuration of wind capacity, a base-caseconfiguration is defined which approximates the dominant trend in the wind industry. In thebase-case configuration, capacity is allocated to sites in the order of their energy capture(capacity factor) until the capacity limit for the selected sites are reached. The improvement ofCFE in the optimal configuration over the base-case configuration is then used as a measure toquantify and illustrate the benefits of optimal spatial diversification.The results of this study show that the CFE of the installed wind capacity in the system improvesby 2% to 4% in the optimally diversified configuration at low levels of wind penetration (10% to20%) and subject to moderate to strict power system generation constraints. For medium levelsof wind penetration (20% to 30%), there is no observed benefits since ramping complicationsfade away at higher levels of penetration. At high levels of penetration (25% to 40%), theminimum generation level constraint results in 5% to 10% CFE improvement in the optimallydiversified configuration.Storage is modeled in the system, as an alternative method of comparing the optimal and basecaseconfigurations. The storage capacity that would be saved by optimally diversifying the windcapacity is determined for different levels of wind capacity installations and subject to varyinglevels of power system flexibility. Power system generation flexibility is modeled by two keyparameters of minimum generation level and ramping capability.The benefits of optimal configuration over the business-as-usual base-case configuration aresignificant at low and high levels of wind penetration whereas the benefits are almost absent atmedium levels of wind penetration. This is explained by the role that the key parameters of thegeneration fleet play at different levels of penetration.

Cultural Bridges: Cultivating Conversations Through Garden Design

Sat, 01 Aug 2009 00:00:00 GMT

Title: Cultural Bridges: Cultivating Conversations Through Garden Design

Authors: Bartlett, M'Lis; Jones, Jenna

Abstract: Landscape architects have a social responsibility to design spaces that improve localecology and engage community members through participatory design methods. CulturalBridges: Cultivating Conversations through Garden Design seeks to become a precedentfor embracing cultural authenticity and ecological integration as inherent componentsof landscape design. Located in Oak Park, Michigan, Cultural Bridges is a proposal forreimagining a public garden in a culturally diverse neighborhood that focused on the Jewishand Islamic communities of the region.Through historic, cultural and religious research on the art, gardens and plants, and theuse of contemporary Jewish and Muslim perspectives on nature and religion, the CulturalBridges design highlights the religious and landscape histories of Oak Park. Given thehistoric confl ict of the Jewish and Muslim cultures, Cultural Bridges illuminates sharedarchitectural, landscape, and ethnobotanical histories as well as shared philosophies onconservation and sustainability. These concepts are translated into the design layoutthrough circulation patterns, gathering spaces, material choices and plant selection.Sustainable site practices including rainwater infi ltration methods and the use of nativeplant species improve the local ecology while supporting the design intent. Signifi cantcultural references from each community were identifi ed and incorporated into a designthat commemorates, educates, and inspires a healing process between these communities.A critical discussion of the design choices suggests that if the community is not open tohealing the disparate relationship between Jews and Muslims, the Cultural Bridges designswill not succeed. A visitor who is open-hearted and willing to work toward a peaceful futuretogether will fi nd many opportunities help promote and cultivate this relationship throughlearning, discussing, and refl ection.

Life Cycle Assessment of Indoor Recirculating Shrimp Aquaculture System

Sat, 01 Aug 2009 00:00:00 GMT

Title: Life Cycle Assessment of Indoor Recirculating Shrimp Aquaculture System

Authors: Sun, Wenting

Abstract: This study analyzed the sustainability and environmental impact of indoor recirculatingaquaculture systems (RAS) used for raising shrimp in the U.S. A life cycle analysis (LCA) wasperformed to evaluate the environmental and energy performance of the system. In the LCAstudy, the functional unit was 1800 kg fresh shrimp, produced by a commercial-scalerecirculating shrimp aquaculture system in the U.S. The life cycle model included the hatchery,recirculating farm, product processing & storage, and transportation stages. The impactassessment method used was Eco-Indicator 95 and the environmental impact categoriesincluded global warming potential (GWP), ozone depletion potential (ODP), acidificationpotential (AP), eutrophication potential (EP), heavy metals (HM), carcinogens, pesticides(PC), summer smog (SS), winter smog (WS) and solid waste (SW). According to the LCAresults, shrimp farming accounted for 95% of the life cycle energy use and caused 82-99.6%of the environmental impacts in the life cycle system.A scenario analysis examining transportation, marketing, farm location, and biosolidshandling was also conducted. Results were sensitive to farm location and marketing scalewhile transportation and biosolids handling were much less significant. Reducing the scale ofthe market reduced environmental impacts due to energy savings in product distribution andstorage. Impacts of the local-scale scenario were just 42-87% of those of the national-scalescenario. Farm location was also significant since the energy use and environmental impactsin mainland coastal farms were 30% and 9-37% of those in the inland farms, respectively.With the same culture technique and product distribution, coastal farms were preferable toinland farms in terms of energy savings and pollution reduction. Moreover, compared toculturing shrimp locally in Michigan, buying shrimp from the Southern coast reduced lifecycle energy by 70% and reduced pollutant emissions by 86-643% for Michigan consumers.In addition, for American consumers, producing shrimp in this country was recommended,over importing shrimp from Asia. Shrimp production and distribution in the US led to a15-82% reduction in pollutant emissions.In comparing culture technique, there was a trade-off amongst energy consumption, water use,and environmental impacts with RAS and conventional flow-through farms. The RAS used70% less water than the conventional system, while the electricity usage in RAS was 1.4times that of the conventional flow-through system. The RAS produced lower GWP, EP, andODP impacts while the conventional farm showed better performance in terms of AP impacts.

Water Resources and Technology Investment Under Uncertainty

Sat, 01 Aug 2009 00:00:00 GMT

Title: Water Resources and Technology Investment Under Uncertainty

Authors: Rice, John

Abstract: Supporting thermoelectric power generation requires a significant quantity of water, primarilyfor cooling operations. Lack of available water due to physical scarcity or thermal permit limitsassociated with the Clean Water Act 316 (a) can result in a forced curtailment of plant operation,known as a “derating event.” Depending on the duration and severity of this derating event, autility can realize millions of dollars in economic loss. To prevent such events, a power plant caninvest in alternative cooling technology that reduces the plant’s dependence on large quantitiesof water for cooling operations. Such investments however, may be difficult to justify due tolarge capital costs for water conservation technologies and highly uncertain future cost ofderating events - future derating costs are a function of climate and energy market prices. Thus,the capital decision to invest is complex. Traditional valuation approaches, like Net PresentValue (NPV) analysis, are unable to properly value irreversible investments in environments ofhigh uncertainty because they fail to account for managerial discretion and flexibility ininvestment. Real options analysis (ROA) has been proposed as a promising solution to thedeficiencies of traditional valuation methods when facing risky technology investments orventures. The valuation technique, rooted in financial option theory, incorporates “Real optionthinking” - the managerial flexibility to capitalize on opportunities as they arise and minimize theimpact of threats - is precisely what is needed when faced with the uncertain future ofirreversible technology investments. This paper applies ROA to an evaluation of the investmentin water saving cooling technology at the Allen Steam Station in the Catawba River Basin ofNorth and South Carolina. The results indicate that the use of an NPV analysis leads to anundervaluation of the project because the option value - the value of managerial flexibility - isnot included in the valuation. The flexibility of managers is an important criterion for makingdecisions regarding sunk cost investments and firms should evaluate investments with techniquesthat incorporate this option value.