Infinite Citizen of the Shaking Tent by Liz Howard

Review of Liz Howard\u27s Infinite Citizen of the Shaking Tent

A new, more efficient waterwheel design for very-low-head hydropower schemes

Very-low-head hydropower constitutes a large untapped renewable energy source, estimated at 1 GW in the UK alone. A new type of low-impact waterwheel has been developed and tested at Abertay University in Scotland to improve the economic viability of such schemes. For example, on a 2·5 m high weir in the UK with 5 m3/s mean flow, one waterwheel could produce an annual investment return of 7·5% for over 100 years. This paper describes the evolution of the design and reports on scale-model tests. These show that the new design harnesses significant potential and kinetic energy to generate power and handles over four times as much water per metre width compared to traditional designs

(WP 2007-02) Valuing Environmental Quality: A Space-based Strategy

This paper develops and applies a space-based strategy for overcoming the general problem of getting at the demand for non-market goods. It focuses specifically on evaluating one form of environmental quality, distance from EPA designated environmental hazards, via the single-family housing market in the Puget Sound region of Washington State. A spatial two stage hedonic price analysis is used to: (1) estimate the marginal implicit price of distance from air release sites, hazardous waste generators, hazardous waste handlers, superfund sites, and toxic release sites; and (2) estimate a series of demand functions describing the relationship between the price of distance and the quantity consumed. The analysis, which represents a major step forward in the valuation of environmental quality, reveals that the information needed to identify second-stage demand functions is hidden right in plain site — hanging in the aether of the regional housing market

Ecological and Engineering Approaches to Optimizing Algal Biofuels

Algae are ubiquitous in natural ecosystems and have been studied extensively due to their versatility for biofuel production. Most of these studies have been conducted on the grounds of synthetic biology and process engineering with few industrial scale projects considering algal community interactions. Such interactions have often indicated the propensity of increasing overall productivity and reducing community invasability, both important characteristics for scalable projects. However, over 30,000 species of algae have currently been identified with another 20,000 estimated to exist. Within this context, elucidation of these relationships remains extremely resource and time intensive. This thesis outlines a strategy for rapid, high-throughput screening of algal community combinations using a microfluidic platform to synthesize millions of parallel, nanoliter-scale algal communities for analysis of biomass accumulation. Model communities were first studied in a bench scale flask experiment and then examined using microfluidic droplets. These experiments showed consistent results on both positively and negatively interacting algal bicultures. Specifically, these include better performance within bicultures of Ankistrodesmus falcatus and Chlorella sorokiniana as well as Chlorella sorokiniana and Selenastrum minutum with lower performance within the biculture of Selenastrum capricornutum and Scenedesmus ecornis. Biofuels provide a unique opportunity for market penetration in one dominated by petroleum based fossil fuels. They serve as renewable and significantly less carbon intensive alternatives. While the holistic success of algal biofuels will hinge on an amalgamation of these scientific fields, rapid screening of algal communities could prove imperative for discovering community interactions and ideally facilitating a mechanistic analysis of how such interactions arise in natural communities.Master of ScienceNatural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/117666/1/DNCarruthers_Thesis_Final.pd

(WP 2010-02) The Demand for Historic Preservation

Historic preservation is commonly used to protect old buildings and neighborhoods from deterioration. In 1981, the City of Milwaukee established a historic preservation commission to develop and maintain a local register of places with historical importance to the area. The commission also reviews all applications for historic status as well as any requests for exterior alterations. As such, there are numerous rules and restrictions that are imposed on property owners once it has been declared a historic site. Thus, while historic designation can serve to internalize the externalities in neighborhoods with historic buildings, it also imposes costs on homeowners who wish to make improvements to their homes. This paper uses a hedonic model to estimate the impact of historic preservation on the sale price of a single family home in the Milwaukee area. Preliminary results show that the impact of historic preservation is positive when it is significant, with the average impact at 26.6%. However, there was significant variation between districts, with the impact significantly positive in 13 of 22 districts used in the sample. Specifically, the positive impact ranged between 11% and 65%, holding other factors constant. None of the 22 districts had a negative and significant impact. An evaluation of spillover effects reveal that just over one third of them displayed positive and significant spillover effects, whereas 21% had negative and significant spillover effects. The remainder were insignificant. An important question is what factors influence this variability in historic preservation effects. The eventual goal of this research is to extend our preliminary analysis to two stages using a recently developed method that employs spatial econometric methods to solve the unique identification problems inherent in hedonic models (Carruthers and Clark, forthcoming in Journal of Regional Science). This will permit us to determine the specific factors that influence these premiums. While the spatial estimates presented in this preliminary work do not permit a two-stage model, we did explore whether implicit prices appear to be correlated with the household income and racial makeup of the neighborhoods in which they are located. The findings show little evidence that the implicit values of historic districts are correlated, but the implicit price associated with historic district spillovers was positively correlated with both neighborhood measures

Engineering Modular Synthetic Microbial Consortia for Sustainable Bioproduction From CO2

Engineering of synthetic microbial consortia has emerged as a new and powerful biotechnology platform with enormous potential for the production of biobased commodity chemicals. In this dissertation, I have designed, constructed, and optimized a tripartite system in which three microbes of differentiated specializations can convert sunlight, carbon dioxide, and atmospheric nitrogen into desired molecules or materials. Specifically, Synechococcus elongatus, a photosynthetic cyanobacterium that exports sucrose, and Azotobacter vinelandii, a nitrogen-fixing bacterium that secretes ammonia, form a symbiotic foundation hypothesized to support a third producer specialist. The tripartite consortia were implemented using a novel experimental set-up for continuous culture and extensive optimization was carried out with insights and guidance from computational modeling of the system dynamics. As a clear and strong proof of concept, I demonstrated various realizations of this tripartite platform, employing producer specialist strains ranging from model microorganism Escherichia coli to widely used industrial chassis such as Corynebacterium glutamicum and Bacillus subtilis. This versatile and modular technology platform offers potential for bioproduction without environmentally or monetarily expensive nutrient inputs thereby a pathway towards sustainable manufacturing of a wide range of bio-products. As an important component of the effort of engineering the tripartite system described above, I also carried out genetic modifications of E. coli K-12, the most widely used microbial chassis in synthetic biology, to enable efficient utilization of sucrose. A multigene csc operon encoding non-PTS sucrose catabolism was randomly transposed into E. coli K-12 using Tn5 transposase. Isolates from the transposon library yielded a range of growth rates on sucrose, including some that were comparable to that of E. coli K-12 on glucose. Narrowness of the growth rate distributions, improved gene expression conferring faster growth compared to that of plasmids, and enhanced growth rate upon transduction into strains that underwent adaptive laboratory evolution indicate that efficient csc expression is attainable and not limiting to cellular growth. Transduction of a csc fast-growth locus into an isobutanol production strain also yielded high titer with significant sustainability benefits. This work demonstrated that random integration is a viable and effective strategy for optimizing heterologous expression within the context of cellular metabolism for certain desirable phenotypes. In the last part of my thesis, through life cycle assessment, I investigated multi-species algal polycultures, which are different yet related CO2-fixing microbial communities. Experimental studies have previously shown that algal polycultures can be designed to enhance biomass production, stability, and nutrient recycling compared to monocultures. However, it remains unclear whether these impacts of biodiversity make polycultures more sustainable than monocultures. I have conducted a comparative life cycle assessment which showed that when algae were grown in outdoor experimental ponds, certain bicultures improved the energy return on investment and greenhouse gas emissions substantially, compared to the best monoculture. Bicultures outperformed monocultures by performing multiple functions simultaneously (e.g., improved stability, nutrient efficiency, biocrude characteristics), which outweighed the higher productivity attainable by a monoculture. These results demonstrated that algal polycultures with optimized multi-functionality lead to enhanced life cycle metrics, highlighting the significant potential of ecological engineering for enabling future environmentally sustainable algal bio-refineries. Collectively, this dissertation demonstrates how CO2-fixing microbial communities may be engineered to enhance sustainability metrics compared to monocultures. By successfully engineering more sustainable bioproduction platforms, we move closer to a society with lower dependence on petrochemicals.PHDChemical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163222/1/dcarruth_1.pd

(WP 2010-11) The Benefits of Environmental Improvement: Estimates From Space-time Analysis

This paper develops estimates of environmental improvement based on a two-stage hedonic price analysis of the single family housing market in the Puget Sound region of Washington State. The analysis — which focuses specifically on several EPA-designated environmental hazards and involves 226,918 transactions for 177,303 unique properties that took place between January 2001 and September 2009 — involves four steps: (i) ten hedonic price functions are estimated year-by-year, one for each year of the 2000s; (ii) the hedonic estimates are used to compute the marginal implicit price of distance from air release, superfund, and toxic release sites; (iii) the marginal implicit prices, which vary through time, are used to estimate a series of implicit demand functions describing the relationship between the price of distance and the quantity consumed; and, finally (iv) the demand estimates are compared to those obtained in other research and then used evaluate the potential scale of benefits associated with some basic environmental improvement scenarios. Overall, the analysis provides further evidence that it is possible to develop a structural model of implicit demand within a single housing market and suggests that the benefits of environmental improvement are substantial

The Demand for Historic Preservation

Historic preservation is commonly used to protect old buildings and neighborhoods from deterioration. In 1981, the City of Milwaukee established a historic preservation commission to develop and maintain a local register of places with historical importance to the area. The commission also reviews all applications for historic status as well as any requests for exterior alterations. As such, there are numerous rules and restrictions that are imposed on property owners once it has been declared a historic site. Thus, while historic designation can serve to internalize the externalities in neighborhoods with historic buildings, it also imposes costs on homeowners who wish to make improvements to their homes. This paper uses a hedonic model to estimate the impact of historic preservation on the sale price of a single family home in the Milwaukee area. Preliminary results show that the impact of historic preservation is positive when it is significant, with the average impact at 26.6%. However, there was significant variation between districts, with the impact significantly positive in 13 of 22 districts used in the sample. Specifically, the positive impact ranged between 11% and 65%, holding other factors constant. None of the 22 districts had a negative and significant impact. An evaluation of spillover effects reveal that just over one third of them displayed positive and signficant spillover effects, whereas 21% had negative and significant spillover effects. The remainder were insignificant. An important question is what factors influence this variability in historic preservation effects. The eventual goal of this research is to extend our preliminary analysis to two stages using a recently developed method that employs spatial econometric methods to solve the unique identification problems inherent in hedonic models (Carruthers and Clark, forthcoming in Journal of Regional Science). This will permit us to determine the specific factors that influence these premiums. While the spatial estimates presented in this preliminary work do not permit a two-stage model, we did explore whether implicit prices appear to be correlated with the household income and racial makeup of the neighborhoods in which they are located. The findings show little evidence that the implicit values of historic districts are correlated, but the implicit price associated with historic district spillovers was positively correlated with both neighborhood measures.Hedonic housing model, historic preservation district, Milwaukee

A Spatial Econometric Model of the Scottish Housing Market, 1980-81

This thesis formulates a spatial econometric model of the Scottish housing market over the period 1980-81. The study is concerned with the role of space in the dynamic operation of an owner-occupier housing market, particularly as applied at the regional level. These four considerations - space, dynamics, tenure, and level of aggregation - are selected for attention after an examination of the approaches to housing market models in a number of disciplines, but in particular within economic and econometric models. It is found that the approaches used in other disciplines can be treated as alternative forms of, or special cases of, those based on the utility maximisation premise of economic theory. Existing utility maximisation housing models are generally specified at the urban level of aggregation, with private rental as the dominant form of tenure. Dynamics are an integral part of urban simulation models but in general the attainability of equilibrium is assumed. The aggregate counterpart to an urban model is a macroeconometric model, which is purely dynamic in specification, and the results from this approach are contrasted with those of microeconomic theories. It is shown that assumptions about the spatial structure of the housing market are implicit in macroeconometric models. Three housing market dimensions or analytical categories - space, time, and house type - are identified, and this provides a basis for the classification of existing models. A matrix formulation is used to specify the theoretical structure of a dynamic regional owner-occupier model, and. the spatial econometric technique of the weights matrix is introduced as a parsimonious method for operationalising the theoretical structure. Empirical estimation of demand and supply equations gives an indication of the nature and scale of spatial interaction effects at the regional level. These indicate that there are grounds for including regional level analysis in any discussion of the operation of the housing market. The results are compared with those of the existing housing market literature, and possible extensions of the matrix formulation show that it is a useful framework for urban level analysis as well. The policy implications which follow from this thesis are then discussed and current policy is examined in the light of these findings