Community-Owned Solar Power and Micro Grids for New York State

This policy brief discusses how community owned solar projects and micro grids offer a sustainable alternative to reliance on the large power grid and polluting fossil fuels. It explains how micro grids work and looks at how they are connected to and can improve standard power grids or macro grids

Enabling Micro-level Demand-Side Grid Flexiblity in Resource Constrained Environments

The increased penetration of uncertain and variable renewable energy presents various resource and operational electric grid challenges. Micro-level (household and small commercial) demand-side grid flexibility could be a cost-effective strategy to integrate high penetrations of wind and solar energy, but literature and field deployments exploring the necessary information and communication technologies (ICTs) are scant. This paper presents an exploratory framework for enabling information driven grid flexibility through the Internet of Things (IoT), and a proof-of-concept wireless sensor gateway (FlexBox) to collect the necessary parameters for adequately monitoring and actuating the micro-level demand-side. In the summer of 2015, thirty sensor gateways were deployed in the city of Managua (Nicaragua) to develop a baseline for a near future small-scale demand response pilot implementation. FlexBox field data has begun shedding light on relationships between ambient temperature and load energy consumption, load and building envelope energy efficiency challenges, latency communication network challenges, and opportunities to engage existing demand-side user behavioral patterns. Information driven grid flexibility strategies present great opportunity to develop new technologies, system architectures, and implementation approaches that can easily scale across regions, incomes, and levels of development

Returns to Human Capital under the Communist Wage Grid and During the Transition to a Market Economy

Under communism, workers had their wages set according to a centrally-determined wage grid. In this paper we use new micro data on men to estimate returns to human capital under the communist wage grid and during the transition to a market economy. We use data from the Czech Republic because it is a leading transition economy in which the communist grid remained intact until the very end of the communist regime. We demonstrate that for decades the communist wage grid maintained extremely low rate of return on education, but that the return increased dramatically and equally in all ownership categories of firms during the transition. Our estimates also indicate that men's wage-experience profile was concave in both regimes and on average it did not change from the communist to the transition period. However, the de novo private firms display a more concave profile than SOEs and public administration. Contrary to earlier studies, we show that men's inter-industry wage structure changed substantially between 1989 and 1996.http://deepblue.lib.umich.edu/bitstream/2027.42/39656/3/wp272.pd

The hybrid grid implemented DSMC method used in 2D triangular micro cavity flows

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this study a new hybrid grid is implemented in a 2D DSMC solver to be used in 2D triangular micro cavity flows. Currently DSMC is the prominent method to analyze micro scale gas flows which are rarefied. Because of the computational cost, DSMC solvers are generally used in rarefied gas conditions in which continuum based solvers are useless. If the efficiency of DSMC solvers is improved, the application range of these solvers can be increased further where the continuum based solvers dominate. Indexing the particles according to their cells is one of the main steps in the DSMC method. Either the particles are traced cell-by-cell along their trajectories or coordinate transformation techniques are used in this step. The first option requires complex trigonometric operations and search algorithms which are computationally expensive. But it can be used in both structured and unstructured grids. Although the second option is computationally more efficient, it demands specially tailored structured grids which are more geometry dependent compared to the unstructured grids. Here it is shown that a novel hybrid grid structure can be used successfully in 2D DSMC solver to analyze triangular shaped lid-driven micro cavity flows. Hybrid grids used in this study are much less dependent of the geometry like unstructured grids. Additionally, hybrid grids like structured grids facilitate coordinate transformation techniques in order to increase the efficiency of the particle indexing step in the DSMC method

A novel approach for protection of radial and meshed microgrids

During grid-connected operation mode of microgrids, since the main grid provides a large short-circuit current to the fault point, the protection can be performed by the conventional protective devices, but in islanded mode, fault currents are drastically lower than those of grid-connected mode. Hence, employment of traditional overcurrent-based protective devices in micro-grids is no longer valid and some alternative protection schemes should be developed. This paper presents a micro-grid protection scheme based on positive-sequence component using Phasor Measurement Units (PMUs) and a Central Protection Unit (CPU). The salient feature of the proposed scheme in comparison with the previous works is that it has the ability to protect both radial and meshed micro-grids against different types of faults. Furthermore, since the CPU is capable of updating its pickup values (upstream and downstream equivalent positive-sequence impedances of each line) after the first change in the micro-grid configuration (such as transferring from grid-connected to islanded mode and or disconnection of a line, bus, or DER either in grid-connected mode or in islanded mode), it can protect micro-grid against subsequent faults. In order to verify the effectiveness of the proposed scheme and the CPU, several simulations have been undertaken by using DIgSILENT PowerFactory and MATLAB software packages

Life cycle energy and carbon analysis of domestic combined heat and power generators

Micro Combined Heat and Power (micro-CHP) generators combine the benefits of the high-efficiency cogeneration technology and microgeneration and is being promoted as a means of lowering greenhouse gas emissions by decentralizing the power network. Life Cycle Assessment of energy systems is becoming a part of decision making in the energy industry, helping manufacturers promote their low carbon devices, and consumers choose the most environmentally friendly options. This report summarizes a preliminary life-cycle energy and carbon analysis of a wall-hung gas-powered domestic micro-CHP device that is commercially available across Europe. Combining a very efficient condensing boiler with a Stirling engine, the device can deliver enough heat to cover the needs of a typical household (up to 24kW) while generating power (up to 1kW) that can be used locally or sold to the grid. Assuming an annual heat production of 20 MWh, the study has calculated the total embodied energy and carbon emissions over a 15 years operational lifetime at 1606 GJ and 90 tonnes of CO2 respectively. Assuming that such a micro CHP device replaces the most efficient gas-powered condensing boiler for domestic heat production, and the power generated substitutes electricity from the grid, the potential energy and carbon savings are around 5000 MJ/year and 530 kg CO2/year respectively. This implies a payback period of the embodied energy and carbon at 1.32 - 2.32 and 0.75 - 1.35 years respectively. Apart from the embodied energy and carbon and the respective savings, additional key outcomes of the study are the evaluation of the energy intensive phases of the device’s life cycle and the exploration of potential improvements