Micro Grids Sustainability Research Project
Abstract
Micro-Grid connections involve the distribution of a new generation of power. This sector has attracted researchers to come up with better ways of generating energy. It is because of the increasing demand for electricity and environmental pollution concern as a new emerging technology for providing reliable and clean power supply. A microgrid comprises distributed generation, energy storage, loads, and a control system that is capable of operating in grid-tied mode or islanded mode. As operation modes, the microgrid should successfully manage the voltage and frequency adjustment to protect the grid and any loads connected to the system. Facilitation of the generation-side and load-side management and the resynchronization process is required.
Introduction
A microgrid is a modern distributed power system using local, sustainable power resources designed through various smart-grid initiatives. It also provides energy security for a local community as it operates without the presence of a more comprehensive utility grid. Microgrid technology generally represents three essential goals of society, such as reliability (physical, cyber), sustainability (environmental considerations), and economics (cost optimizing, efficiency). The “distributed generation” (DG) term refers to power generation located near the consumption sites. By comparison to the “central age, ” DG can eliminate the production, transmission, and distribution costs while increasing efficiency by removing elements of complexity and interdependency. In many cases, distributed generators can provide lower generation costs, higher reliability, and increased security not realized via traditional generators.
North America leads to a global microgrid generation with 2,088 MW operating capacity, according to the report. Europe is the second with 384 MW while Asia Pacific follows with 303 MW of operating capacity. The installed microgrid capacity in the rest of the world is around 404 MW. If each power user (building/company/hospital/market) cares about reliable power and eep their desire to back up energy sources like generation/battery/diesel engine, that would be the most expensive power system. In a microgrid system, backup resources are unnecessary because a single user does not have to supply a general load during critical consumption periods.
Background of the Problem
The world has re
cently been changing and embracing better energy-efficient ways to generate energy. To rein in electricity costs, replace aging infrastructure, improve resilience and reliability, reduce CO2 emissions to mitigate climate change, and provide reliable electricity to areas lacking electrical support.
From the 1920s through the 1970s, the increased reliability afforded by connecting multiple generating units to diverse loads, decreased construction costs per kilowatt (kW), and ability to draw power from distant massive generating resources like hydropower drove the development of the grid we see today. However, those advantages seem to have reached their limits and are increasingly undermined by environmental and economic concerns. Driven by utility restructuring, improved DER technologies, and the financial risks that accompany the construction of massive generating facilities and transmission infrastructure, companies that produce electricity have been gradually shifting to smaller, decentralized units over time [3].
Key Performance indicators
Power Quality The first KPI that will be examined in this section is power quality indicators. This category can be divided to different subcategory such as THD, demand, demand factor and load factor. Harmonics in Power Systems In mentioned that power system harmonics are not a new topic. When Fourier methods are used in order to analyze the distorted waveform is that the waveform is in steady state. In reality, waveform distortion varies a lot and it depends on both load levels and system conditions. the harmonics in the power system can be limited by two different methods. The first one is the harmonic limits for the harmonic current which a user can inject into the utility system at PCC. The second set of harmonic limits is for the harmonic voltage that the utility can provide to any customer at the PCC. The acceptable distortion is decreased at higher voltage levels in order to minimize potential problems for the majority of system users.
Demand is a measure of the energy that loads require over short periods of time and it is expressed in terms of power (kilowatts or Megawatts). Demand, as commonly referred to in utility discussions as integrated demand, can be measured over 10, 15, or 30 min. Demand Factor is a ratio of the maximum demand to the total connected load of a system or the part of the system under consideration. Reliability can be subcategorize as wind generation indices and power system reliability indices. Wind Generation Indices is the index of the wind generation interrupted energy benefits. It shows the reliability worth of adding wind generation as an alternative supply. Load point reliability indexes, including the following three aspects: 1) λ :frequency of load interruptions (occurrences per year); 2) r :average duration of load interruptions(hours per occurrence); 3) U : average annual duration of load interruptions (hours per year).
The Economic Indicator The economic indicator has five second-class indicators: capital cost, maintenance cost, generation cost, replacement cost, and power loss cost in US$. a) Capital Cost Capital cost or lifecycle cost has been used to decide economic feasibility of a system [66]. Microgrid with lowest capital cost is always preferred.
Performance indicators: Apply environmental, social and economic management tools and develop a score or set of scores on proposed sustainable alternative
Commercial viability: Biofuel production has been assisted by generous tax credits to refiners, currently $0.45 per gallon for corn ethanol and $1.01 per gallon for cellulosic ethanol, to make it commercially viable (PEW 2009).
Environmental impact: A potential benefit of biofuels is lower life-cycle greenhouse gas emissions (Farrell et al. 2006; Hill et al. 2006; Wang et al. 2007). Yet, if biofuel expansion causes conversion of forests, wetlands, or native grasslands to croplands, the carbon debt from land-use change can take decades to centuries to repay (Fargione et al. 2008). Increased biofuel production can put pressure on local water supplies and may lead to declines in regional water quality (NRC 2008a). Also, concerns about impacts of changes in land use include the potential negative impacts associated with the expansion of biofuel production on marginal lands and withdrawal of the land from the Conservation Reserve Program (NRC 2010). Biofuel production can also cause an increase in air pollution (Hill et al. 2009)..
Application of Sustainability Tools
To incorporate sustainability effectively within EPA and to achieve external adoption in various sectors, EPA will have to make use of a variety of assessment tools. EPA will need to develop a set of tools or models that can be used to quantify impacts on important, social, environmental, and economic indicators that might be affected by the program, policy, or project under evaluation. Such tools can provide a uniform and transparent basis on which to evaluate alternatives. The broadening of the analysis from environment and human health to sustainability means that instead of or in addition to risk assessment, additional economic and social factors will need to be considered. This process also means that EPA will need to adopt, develop, or modify a set of tools to conduct such analyses that go beyond traditional risk assessment.
Risk Assessment
Risk assessment is a tool widely used for characterizing the adverse human health and ecologic effects of exposures. Classically, risk assessments for human health endpoints involves four major steps: a hazard identification, dose-response assessment, exposures assessment and risk characterization (NRC 1983, 1994, 2009; EPA 2005). In the hazard identification step a determination is made about the type of effects potentially caused by the environmental exposure. In the dose response step, the level of exposure such as dose or air concentration is related to the level of adverse effect, such as the incidence of a health effect from an environmental exposure. The exposure assessment characterizes elements of the exposure, for example its intensity, frequency, and timing. The risk characterization combines the dose response and exposure assessments to produce descriptions of the risk for the variety of adverse effects determined in the hazard identification step. In this last step, the uncertainty in the description is also characterized along with variability of the effects in those exposed. For example, a risk assessment may include predictions of the increased incidence of cancer from an environmental chemical exposure in the general population or highly exposed groups or of the margin between the environmental exposure and that causing a noncancer effect seen in the laboratory or in human studies. A wide variety of analytic approaches and tools are used in conducting a risk assessment. Risk assessments are important inputs into the process of establishing environmental regulations, cleanup levels, and permitting industrial facilities. An important consideration in any sustainability action is whether environmental or human health will be better or worse off if an action is taken, both near term and.
Life-Cycle Assessment
Life-cycle assessment is a “cradle-to-grave” analysis (or “cradle-to-cradle” ([McDonough and Braungart 2002]) of environmental impacts from production, use, and eventual disposal of a product. Life-cycle assessments are used to analyze the major environmental impacts of various products, to determine how changes in processes could lower the environmental impact, and to compare the environmental impacts of different products (Blackburn 2007). Life-cycle assessments are already used by EPA and have been used to compare the environmental impacts of transportation fuels and specifically to judge whether biofuels meet requirements for carbon-emissions reductions relative to fossil fuels (EPA 2009). Life-cycle assessments take a systems perspective to include the whole production process, from production of raw materials to eventual disposal and is therefore consistent with, and often an essential component of, sustainability analysis.
Benefit-Cost Analysis
Benefit-cost analysis is a widely used tool from economics to evaluate the net benefits of alternative decisions. Benefit-cost analysis seeks to assess the change in welfare for each individual affected by a policy choice, measured in a common monetary metric, under a set of alternatives. Most benefit-cost analyses then aggregate the measure of individual net benefits to find a social net benefit and then rank the alternatives. There have been concerns that benefit-cost analysis as commonly applied to environmental issues places too much emphasis on the economic costs and too little on benefits and their distribution (OECD 2006
Ecosystem Services Valuation
Ecosystem services are goods and services that contribute to human well-being and are generated by ecosystem processes. For example, ecosystems can filter contaminants to provide clean water for human use and modulate water flow, reducing the probabilities of flooding and providing higher flows during drier periods. Ecosystem-service valuation is an attempt to measure the relative benefits of ecosystem services in a common metric (usually a monetary metric). Ecosystem-services valuation requires integration of ecological and other natural sciences.
Sustainability Impact Assessment
Sustainability impact assessment is used to analyze the probable effects of a particular project or proposal on the social, environmental, and economic pillars of sustainability. This assessment is also used to develop integrated policies that “take full account of the three sustainable development dimensions” and include the “cross-cutting, intangible and long-term considerations” of those policies (OECD 2010). Sustainability impact assessment is used in many European countries and in Canada but has not been used to any great extent in the United States (Zerbe and Dedeurwaerdere 2003).
CONCLUSIONS AND RECOMMENDATIONS
Present Conditions and Future Scenario Tools
The Sustainability Assessment and Management approach requires an evaluation of present and future conditions to show that present decisions and actions are not compromising future human and ecologic health and well-being. A requirement of these elements, therefore, is to be able to forecast potential future conditions as a function of the decision option chosen. The forecast should take into account both the decision options and the underlying biophysical, social, and economic forces that will influence system dynamics.
Forecasting conditions relevant to sustainability poses a paradox. There is no standardized universally accepted way to forecast the future and, in fact, most forecasts are wrong to a greater or lesser degree. On the other hand, almost all policy actions are premised on assumptions about future conditions. Forecasting is unavoidable when dealing with sustainability, but our ability to do forecasting is limited. At a minimum, this means that the forecasted premises needs to be made explicit and the uncertainty of the forecast also needs to be explicit because the robustness of the sustainability assessment will depend on the degree of uncertainty of the forecast.
One standard approach to specifying future conditions is to use scenario analysis (Schwartz 1991). Creative thinking about a set of scenarios can highlight the potential range of plausible future outcomes. Scenarios, such as a range of scenarios about land-use change, can be used at local or regional levels. See Box 4-2 for an example of such a scenario for global biodiversity.
Trade-off and Synergy Analysis
Trade-off and synergy analysis is a fundamental component of the Sustainability Assessment and Management approach. The objective is to maximize synergies (social, environmental, and economic benefits of a decision) and to minimize the adverse effects of conflicts among the three pillars. Because conflicts lead to trade-offs among the three pillars and because improperly managed trade-offs can compromise environmental protection, public health, or other key aspects of sustainability, clear trade-off rules are required. Most basically, “tradeoff decisions must not compromise the fundamental objective of net sustainability gain” (Gibson 2006, p.175). OECD recommends,
It will be important for EPA to establish a systematic way to analyze and quantify alternatives. One approach to analyzing conservation and management alternatives was used in the application of spatially explicit models of multiple ecosystem services and biodiversity conservation (Polasky et al. 2011). These models illustrated how predictions could be used to analyze alternative conservation and management strategies, and by comparing maps of ecosystem services and biodiversity, decision makers could identify areas that provide high levels of both. Outcomes compared across different management alternatives give insight into which alternatives are best. The analysis can be used to identify new strategies that may improve results for key ecosystem services or biodiversity conservation objectives. Gibson (2006) provides guidelines for approaching trade-off analysis:
Maximum net gains: Any acceptable trade-off or set of trade-offs must deliver net progress towards meeting the requirements for sustainability; it must seek
mutually reinforcing, cumulative and lasting contributions and must favor achievement of the most positive feasible overall result while avoiding significant adverse effects.
Burden of argument on trade-off proponent: Trade-off compromises that involve acceptance of adverse effects in sustainability-related areas are undesirable unless proven (or reasonably established) otherwise; the burden of justification falls on the proponent of the trade-off.
Avoidance of significant adverse effects: No trade-off that involves a significant adverse effect on any sustainability requirement area (for example, any effect that might undermine the integrity of a viable socio-ecological system) can be justified unless the alternative is acceptance of an even more significant adverse effect.
Protection of the future: No displacement of a significant adverse effect from the present to the future can be justified unless the alternative is displacement of an even more significant negative effect from the present to the future.
Explicit justification: All trade-offs must be accompanied by an explicit justification based on openly identified, context-specific priorities as well as the sustainability decision criteria and the general trade-off rules.
Open process: Proposed compromises and trade-offs must be addressed and justified through processes that include open and effective involvement of all stakeholders.
The above examples of evaluating trade-offs are illustrative of the type of analysis EPA will need to undertake. The committee expects that EPA will adopt trade-off rules that are consistent with its existing legal authority and that are based on consideration of trade-off rules used elsewhere. The committee also expects that these trade-off rules may change over time as EPA gains greater experience with their use.
Communication of Results to Decision Makers
Following scoping and options identification, screening evaluation, application of tools, and trade-off and synergy analysis, communication of results will need to be integrated into the decision-making process at a point when the information can be considered in formulating the policy or program or taking a major action subject to sustainability review. Results should be available as early as is practicable; an assessment may show the need for further information or action on particular issues. The roles of the decision makers and the offices contributing expertise will need to be defined and accountability measures should be in place to ensure that the decision maker gives due consideration to the results of the assessment in acting on the subject.
Decisions Taken and Implemented
A series of briefing documents at a depth appropriate to the decision would probably be prepared to inform the decision making. The range of options and the associated social (including health), environmental, and economic impacts for each option would be presented along with any trade-off analyses that may have been undertaken. As is the case with alternatives analysis under NEPA, options in a sustainability assessment allow the decision maker to understand different ways of taking a particular action and thus provide the decision maker with more choices to reduce adverse impacts. In addition, options in a sustainability assessment allow the decision maker to find better ways of improving social well-being, economic development, and environmental protection at the same time. Options also make clearer the causes of any trade-offs among the three pillars and help the decision maker to reduce the adverse effects of any trade-offs. Questions could arise that would require some additional analysis as well as follow-up with various stakeholders and collaborators.
Evaluation of Outcomes
An important component in communicating the potential benefits of adopting sustainability and justifying further efforts directed toward sustainability is demonstrating the effectiveness of prior actions and providing the information to be used in the feedback loop to modify goals. Such work goes by such names as project evaluation, post facto evaluation, or accountability analysis (NRC 2005b). Evaluation is useful in identifying best practices, reducing uncertainties, and identifying additional linkages. Evaluation, like tools and indicators, is founded on having the appropriate data. There is a significant literature on program evaluation, including methods for measuring program performance, including but not limited to Cronbach 1980, Chelimsky 1997, Vedung 1997, Stufflebeam 2001, and Posner 2004.
Identifying the most appropriate indicators can be driven by models; for example, sensitivity analysis can be used to quantify how system indicators will respond to perturbations (e.g., policies and projects). The dual role of sustainability indicators is to both measure and communicate the range of factors that are involved in the decision-making process. Indicators, generally, are measures of the system of interest and can be either directly observed or derived quantities.