Browsing by Subject "Renewable energy"
Now showing 1 - 14 of 14
Results Per Page
Sort Options
Item Cook County and Grand Marais Energy Conservation and Renewable Energy Plan(2012) Cook CountyThis planning document is heavily focused on energy requirements and future energy planning. There is little mention of water or other natural resources, although habitat and bird migration is discussed in the context of wind energy. Key points are summarized below. Summary: The energy planning process included a survey with 28 questions to solicit information concerning awareness of energy issues, attitudes toward energy issues, and what respondents had done to address these issues. Respondents overwhelmingly viewed movement toward use of renewable energy as very favorable and indicated a willingness to pay a premium of about 6% for renewable energy. Energy profile information was gathered for both Cook County and Grand Marais showing how, where, and how much energy is currently being used. This information was used to develop and prioritize the Plan's Goals, Strategies and Action Steps, and will be useful for measuring Energy Plan progress, and changes in energy use over time. The first phase of the study has been completed. It addresses the availability of forest biomass for energy production in Cook County; options for biomass combustion technology for small, medium, and large systems; and financial implications of converting to biomass energy in various Cook County settings. In a related effort, a bird migration study was undertaken by the Natural Resources Research Institute to assess the possible detrimental effects of locating wind turbines in the North Shore bird migration corridor. The study suggests that wind turbines located in Cook County, especially within 1 mile of the shore, might result in significant bird mortality. A list of goals, strategies and action steps are presented. No other water-related content was identified in the planning document and appendices.Item Cook County and Grand Marais Energy Conservation and Renewable Energy Plan Appendices(2012) Cook CountyThis is a series of annexes to the final report, and containing the following materials: Public Survey Results (Powerpoint presentation); Energy Toolbox Resources; Biomass Phase I Report Executive Summary; and Wind Feasibility Study. As noted in the previous document, there is little mention of water resources.Item Cook County Local Energy Project - Project Resume(2015)This item contains descriptions of events and projects, with details regarding dates and funding, for aspects of the Cook County Local Energy Project: Project Resume. Dates span 2008-2016.Item Electricity generation with organic matter and ammonium removal from swine wastewater via microbial fuel cells(2013-11) Lin, HongjianLivestock industry generates a large amount of manure and wastewater. Minnesota, the third largest hog producing state in the US, produces 7 million pigs per year and meanwhile generates 11 million tons of dry manure. Wastewater from swine farms contains high concentrations of organic matters, nitrogen and phosphorus. A poor management and treatment of the wastewater would cause severe environmental issues to soil, water, and air, such as eutrophication, impairment in drinking water quality, and the odor issue. So an appropriate treatment of the swine wastewater is an urgent and crucial issue to sustain the industry. Microbial fuel cell (MFC) is an emerging technology that shows a potential use in swine wastewater treatment. The reactor realizes biological oxidation at anode for organic matters, and electrochemical reduction at cathode. It is sustainable because it converts waste to electricity, recovers nutrients, and reduces the cost for wastewater treatment. The overall goal of this study is to develop effective MFCs for treating synthetic and swine wastewater to generate electrical energy and, at the same time, to achieve efficient removal of COD and total ammonium nitrogen. The first step was to choose suitable bacterial consortia to inoculate single-chamber air-cathode MFCs. Activated (AC) and anaerobic (AN) sludge showed faster enrichment of MFC anodic biofilm by 2 to 3 d than river sediment (RS), while AN-MFC presented highest VFA degradation rate, indicating that the bacteria in AN sludge were better adapted to MFC anodes due to the similar anaerobic environment and volatile fatty acid concentrations in a swine manure anaerobic digester. However, RS-MFC anode surface was covered with well-developed layers of biomass (bacterial cells and extracellular polymeric substances) and had a much larger power output (195 μW or 98 mW m-2) than AC- and AN-MFC after one month operation. For mature MFCs that were under long-time operation, a transient application of negative voltages (-3 V) improved the cathode activity and maximum power output by 37%, due to the bactericidal effect of the electrode potential higher than +1.5 V vs. standard hydrogen electrode (SHE). The second step was to model the single-chamber MFCs based on the assumption that the anode attached bacterial monolayer serves as biocatalysts for MFC exoelectrogenesis. By modifying the Freter model and combining it with Butler-Volmer equation, this model adequately describes the processes of electricity generation, substrate utilization, and suspended and attached biomass growth, in both batch and continuous operational mode. The results showed that the activation overpotential of the anode substantial reduced during the anode enrichment process, which was a result of increased exchange current density due to the increased biocatalyst. It was also found that electricity generation reduced sludge generation. Smaller external resistors were suggested to use to improve the organic matter removal and to reduce sludge generation, while an external resistor close to the internal resistor should be used to obtain the maximum power generation. The third step of this study modeled the kinetic data of swine wastewater characteristics in MFCs, including conductivity, COD, volatile fatty acids (VFAs), total ammoniacal nitrogen (TAN), nitrite, nitrate, and phosphate concentrations. The removals of VFA and TAN had the half-life times of 4.99 and 7.84 d, respectively. Among the removed TAN, 13.6% was recovered from the evaporated air outside of MFC cathode, indicating its potential use for ammonium recovery from animal wastewater. The mechanism for phosphate removal was principally the salt precipitation from cathode, and needed improvement as the removal was far from completion. MFC with an external resistor of 2.2 kΩ and fed with raw swine wastewater generated relatively small power (28.2 μW), energy efficiency (0.37%) and Coulombic efficiency (0.15%). The main reason for the impaired performance was the inhibitory effects associated with TAN on Pt activity and VFA on anodic biofilm activity. Diluted swine wastewater, with a dilution factor of 2 or higher, dramatically improved the power generation as the inhibitory effect was reduced. Smaller external resistor in the circuit promoted the organic matter degradation and shortened the required reaction time in batch mode. The fourth step was to reduce the inhibitory effect of swine wastewater in electricity generation by selective removal of ammonium and VFAs. This study showed that sorption using natural zeolite was an effective way for ammonium mitigation in swine wastewater. The kinetic process of the ammonium sorption on zeolite was best described by the pseudo-second-order model, and the resulting TAN sorption capacity at equilibrium was 11.6 mg/g. The isotherm data were best fitted by the Langmuir model, and the maximum TAN sorption capacity was 34.2 mg/g. The thermodynamic parameters indicated the spontaneity (ΔG° = -6.65 kJ/mol by the Langmuir model) and exothermic nature (ΔH° = -22.3 kJ/mol) of ammonium sorption on zeolite. Addition of GAC in zeolite decreased ammonium diffusion to zeolite particles, but it enhanced the maximum zeolite sorption capacity and COD (mainly VFAs) removal. Zeolite and GAC were effective in the selective adsorption of ammonia and VFAs in swine wastewater and consequently improved the power generation by over 80%, energy efficiency by up to 78%, and Coulombic efficiency by up to 37% of microbial fuel cells. The final step was to optimize air-cathode and MFC configuration for ammonium removal. The 5% PTFE-treated cathode had a leaking problem, while the other cathodes, including 20% PTFE+GDLs, 5% PTFE+GDLs, and 20% PTFE, did not have the problem of leaking, and the last one performed best both in power generation and ammonia removal. Tests in MFCs A and C revealed that the half-life time of the total ammonium was proportional to electrical current, which was a strong evident demonstrating that the oxygen reduction reaction at cathode promoted ammonia volatilization by elevating pH nearby. On average, an increase of 1 mA in electrical current would reduce the half-life time by 2.8 d and 0.85 d for MFC A and C, respectively. Modifying regular MFCs to membrane contactor mode improved ammonia removal, because the surface area of hydrophobic membrane was increased. This improvement was indicated by the substantially reduced half-life time from the best case of 2.54 d of the best performed regular MFCs to only 0.67 d. The modification also allowed ammonia recovery from wastewater, and 78% of the removed ammonia was captured in sulfuric acid solution. This study demonstrated a novel way of ammonium recovery from wastewater by MFCs based on membrane contactor mode, and better performance is still expected through optimizing the gas-diffusion materials and reactor configuration.Item Final Report: Demonstration of Use of Torrefied Biomass in Electric Power Generation(University of Minnesota Duluth, 2018-03-31) Fosnacht, Donald RDuring this task, a literature review was produced that highlighted some of the characteristics of torrefied fuels and the various efforts to develop commercial systems for its routine production (APPENDIX A). The report highlights work in Europe and subsequent work undertaken during this project and illustrates that energy contents approaching sub-bituminous coal can be produced, but also indicates that the new fuel is chemically reactive and must be handled appropriately. In addition, the results indicate that the biological reactivity relative to white pellets is dramatically reduced. The raw torrefied, undensified fuel is moisture resistant, but densified materials have less moisture resistance and can degrade depending on the binders used in producing the compacted fuel materials. Therefore, the ability to concentrate the energy levels while simultaneously meeting various physical property requirements was noted as an active development by European investigators and a key focus area for the work undertaken by the Natural Resources Research Institute (NRRI). Various tests were completed in using torrefied fuel produced under a variety of conditions. The first test was conducted by Southern Company’s Gulf Power Subsidiary at the Plant Scholz in Florida before active implementation of this project. The test demonstrated that material substitution up to 100% could be attained using torrefied fuels as a coal substitute. The test also indicated that the material is reactive and must be handled similarly to sub-bituminous coal. This test also indicated that further enhancement of torrefied fuel properties should be undertaken in order to improve the overall efficiency of the fuels in power plant operations. The work undertaken at Plant Scholz will be summarized in this report. The trials at the various power plants clearly have shown that torrefied fuels can be a significant substitute for sub-bituminous coal without massive capital expenses to accommodate the use of the advanced biomass-based fuel. But it is also very clear that substantial improvements in physical properties that allow reductions in dust generation, improved moisture resistance, and reduced operator intervention relative to coal are still desired. The tests at the power plants noted illustrate that significant growth in knowledge for use of this new fuel is attained as the trial size increases and as the characteristics of the fuel are more clearly understood.Item Integrating Renewable Energy into Commercial Street Lights(2015) Hemenway, Andrew; Egbue, OnaItem Momentum - Winter 2012(2012) University of Minnesota: Institute on the EnvironmentItem Pumped Hydro Energy Storage (PHES) Using Abandoned Mine Pits on the Mesabi Iron Range of Minnesota – Final Report(University of Minnesota Duluth, 2011) Fosnacht, Donald RThis project focuses on developing an energy storage capability within Minnesota that will enable a larger build‐out of variable renewable generation sources. Currently, a significant challenge associated with the predominant renewable resource in our region (wind) is the variable and off‐peak nature of the energy generated. This feature of some renewable generation systems can, unfortunately, cause: (1) the need to build new fossil fuel generating facilities; (2) operation of existing fossil fuel generating facilities at inefficient levels; (3) transmission grid instability and unreliability; and (4) higher electricity rates. Energy storage is key to overcoming these problems. Currently, the only viable means of storing energy on a large scale are through pumped hydro energy storage (PHES), compressed air storage systems or liquid sodium sulfide battery systems. Fortunately, Minnesota has a unique and largely untapped resource for PHES in the form of idled taconite mines on the Mesabi Iron Range. The goal of this research project was to determine the potential viability, environmental sustainability and societal benefits of PHES as a vital, enabling technology for wind turbine‐based power generation. The intent of this research is to provide a clear roadmap for PHES development in Minnesota. The project is multifaceted and draws resources across the University System and from key industrial partners: Great River Energy and Minnesota Power. The results from the project provide vital information to decision makers on the potential of PHES and give guidance on how the technology can be implemented using the unique assets of the Minnesota Iron Ranges so that renewable mandates and green house gas reduction can be effectively accomplished. The results show that the topography and water resources exist at various sites that could allow a 100 to 200 MW facility to be constructed if the overall economic, mineral rights, and environmental issues associated with a given site can be properly managed. The report delves into the possibilities and outlines selection criteria that can be used for site selection. Other information is developed to compare the potential economic impact of implementation of the project within the constraints of the factors that can be monetized using the current policy environment. Finally, potential life cycle, regulatory, environmental, and permitting issues that are associated with implementation of the concept are discussed.Item Renewable Energy for Minnesota's Future(2020) Hanson, Aaron; Leighton, Chris; James, Richard D; Jalan, Bharat; Shen, Lian; Mohan, NedItem Source, Fall-Winter 2009(University of Minnesota Extension, 2009) University of Minnesota ExtensionItem Source, Spring-Summer 2007(University of Minnesota Extension, 2007) University of Minnesota ExtensionItem Source, Spring-Summer 2008(University of Minnesota Extension, 2008) University of Minnesota ExtensionItem Towards a flexible and energy adaptive datacenter infrastructure(2013-06) Murugan, MuthukumarThe sustainability concerns of Information and Communication Technology (ICT) go well beyond energy efficient computing and require techniques for minimizing environmental impact of ICT infrastructure over its entire life-cycle. The number and popularity of large scale datacenters that host various Internet services, has increased significantly in the recent past. Electricity costs contribute to more than 31% of the overall costs in these datacenters. The increasing energy demand coupled with emerging sustainability concerns requires a re-examination of power/thermal issues in datacenters from a larger perspective of short term energy deficiencies and thermal constraints and ways to make operation of these datacenters more sustainable. The energy deficient scenarios arise for a variety of reasons including variable energy supply and inadequate power, thermal and cooling capacities. Traditionally, ICT infrastructure is overdesigned at all levels from chips to entire datacenters and ecosystem. The paradigm explored in this thesis, called energy adaptive computing or EAC is to replace overdesign with rightsizing coupled with smarter control. The goal of the Energy Adaptive Computing (EAC) paradigm is to address more directly the issue of sustainability of ICT. This is done by attempting to reduce the carbon footprint of the infrastructure via two mechanisms in addition to intelligent energy management: (a) replacing the wide-spread overdesign of the infrastructure components with rightsizing coupled with smart control to handle occasional overshoot in resource-particularly the energy-requirements, and (b) operation on renewable sources of energy. Renewable energy sources often have variable output and also require intelligent adaptation to the energy envelop. After a brief introduction to EAC, the challenges associated with EAC in various environments in terms of the adaptation of the workload and the infrastructure to cope with energy and cooling deficiencies, are laid out in detail. This thesis focuses on the issues related to realizing EAC in a cluster environment inside a datacenter. There are three cluster-EAC scenarios studied in detail in this thesis. (1) First, this thesis presents a controller called Willow that aims at achieving energy adaptation in a datacenter environment, and addresses the problem of simultaneous energy demand and energy supply regulation at multiple levels from servers to the entire data center. The proposed control scheme adapts the assignments of tasks to servers in a way that can cope with the varying energy limitations. (2) Second, this thesis describes the design and implementation of energy adaptation mechanisms for data centers with potentially multiple tiers of service. Energy adaptation is realized by intelligent allocation of energy at various levels of the hierarchy and shutting down of over-provisioned servers. It is shown that energy adaptation could substantially reduce the power drawn from the conventional electric grid and support most datacenter operations with renewable energy sources and yet provide the required quality of service. This is achieved via coordinated control operations at different time granularities and planning strategies for executing the control operations in order to support different workloads without violating their delay bounds. (3) Finally, this thesis proposes a flexible and energy adaptive object storage framework that can adapt to variations in available or consumable power and its performance is investigated in the context of deduplicated virtual machine disks. The design and implementation of a prototype of the object storage framework is presented. The object storage framework has an adaptive replication mechanism and an adaptive consistency model for the replicas. The replicas of deduplicated virtual machine disks are managed dynamically to provide improved performance and to adapt to power constraints. Smart control techniques are proposed to cope with the power constraints either introduced as a result of increasing node density in the storage arrays or introduced when a mix of renewable (green) and conventional (brown) energy sources are used to power the datacenter. The experimental results demonstrate the ability of the framework to dynamically adapt to the changes in workload and power constraints and minimize adverse performance impacts.Item Use of Improved Densification Conditions for Producing High Fuel Content Products from Biomass Processed by Torrefaction, Hydrothermal Carbonization, and Various Densification Methodologies: Final Report(University of Minnesota Duluth, 2018-03-31) Fosnacht, Donald R; Hagen, Timothy S; Young, Matthew; Carden, Kendall; Kiesel, Richard FThe Natural Resources Research Institute is engaged in work to develop demonstration-level production of solid biofuel densified products that can be stored outside, have high bulk densities for ease of logistical transport, have good handling characteristics that minimize dust generation, possess grindability that is like coal used in power plants, and have fuel contents that match or exceed sub-bituminous coal levels. During the work, two pretreatment technologies have been investigated for concentrating the energy content of raw biomass. These include: torrefaction using an indirectly fired rotary kiln process at the demonstration level and hydrothermal carbonization at the bench and pilot scale. The Institute has also collaborated with Syngas technologies on a pilot-scale moving bed, directly heated steam-based process at the pilot scale and next year will install this technology at the demonstration scale. A key factor in showing the full technical feasibility of using the pretreated materials is to demonstrate that the produced particulate fuel products can be densified to a level that allows good logistical and handling practices to be routinely attained. It has been found that hydrothermally carbonized processed materials can be agglomerated using a variety of densification devices including pelleting and briquetting in a repeatable and practical manner using commercial densification equipment with and without the use of binders. However, torrefied materials have proven to be much more difficult to densify using a variety of densification equipment, especially as the degree of torrefaction increases. Uniformly torrefied materials at high energy level appear to be especially difficult to densify but have the attributes of high fuel value and good grindability, with very little residual fiber content compared to less-torrefied material or steam-exploded biomass. Therefore, the work undertaken and explained in the following discussion has been conducted and shows that highly torrefied materials can be satisfactorily densified to produce high-energy-content products that have good physical properties, possess acceptable moisture resistance, low ash, sulfur and mercury content, and have bulk densities that can lead to improved logistics. The densification practices involve optimizing overall process conditions on an integrated systems basis and include moisture level, densification pressure, mix preparation pressure, and the use of appropriate binders when required. The densification system that seems to show the greatest promise for the highly torrefied materials is briquetting. Work will continue in examining other densification options and in improving the conditions used and discussed in this report.