Microgrids: An Environmental Design and Policy Perspective

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Microgrids: An Environmental Design and Policy Perspective
Introduction
Out of a total global population of 7 billion, about 1.3 billion people lack access to modern supply of energy. According to the International Energy Association (IEA), it is estimated that out of the 1.3 billion, 622 million Africans have no access to electricity. Out of the 1.3 billion population without energy supply, 621 million people live in Sub-Saharan Africa and only a million people come from the Northern region of the African continent (Akinyele, Belikov, and Levron 1). Recently, there has been an increasing interest in the use of microgrids globally due to their potential to achieve a dependable, flexible, smart, and efficient electrical grid system, the capacities to supply electric energy particularly to communities living off-grid, and for the economic purpose (Warneryd, Hasansson and Karltorp 6). The characteristics of microgrids and the commitments to achieve a low-carbon environment by governments, policymakers, industries, developers, and other stakeholders have inreased the adoption of microgrids as a dependable option of electric energy generation in the present and the future (Phommixay, Doumbia and St-Pierre 74). While staggering amounts of research studies have explored microgrid technologies and their potential usage, there is a lack of considerations examining the use of microgrids from the perspective of environmental design and policy or city planning. This paper provides various definitions of microgrids, ways in which they can be used to increasing community resilience to disasters, and potential challenges to implementing microgrids more widely.
Definition of Microgrids
While there are various ways of defining microgrids, they are generally described as smaller versions of electric power grids. In general, microgrids refer to a localized arrangement of sources and loads of electricity operating in association with an already existing grid system (on-grid mode) or as a stand-alone system when it is disconnected from the grid system (off-grid mode) (Hirsch, Parag and Guerrero 406). Microgrids are also considered to be small-scale systems of electric power that are specially designed to supply electric energy to small and remote communities. However, the grids can differ in sizes and capacities depending on their scales. In terms of scale, there are mini-microgrids (0.001-0.005 MW), small microgrids (0.005-5MW, medium microgrids (5-50MW), and large distributed generation (DG) (50-300 MW) (Akinyele, Belikov, and Levron 5). The incentives to the deployment of microgrids among communities living in off-grid areas include the lack of access to the national grid, economic factors, and the remoteness of such locations. Based on energy sources, microgrids are classified into solar, wind, hydro, agro-waste, energy crops, fuelwood, animal waste, municipal solid waste, sawdust, and wave and tidal energy (Akinyele, Belikov, and Levron 5). These energy sources are either renewable (solar, hydro, wind, geothermal, biomass) or conventional non-renewable sources such as gas/steam turbines and micro-turbines. However, to align with the goals of environmental policymakers of achieving a globally sustainable energy future, communities around the world have supported the use of eco-friendly microgrid technologies utilizing solar, biomass, wind, and hydro sources.
Microgrids and Community Resilience to Disasters
Extreme weather events often cause failures in power systems that can result in overwhelming consequences. Historically, natural disasters such as tornadoes and hurricanes have caused excessive damages to affected communities. According to Chen et al (1), there were 16 natural disasters in 2017, including hurricanes Maria and Harvey, which led to more than 300 million dollars in damages. In particular, power systems are often susceptible to such disruptions and may cause over 80% of long-term power outages (Chen et al., 1). For instance, the 2017 Hurricane Harvey left more than a quarter-million people in the state of Texas without electric power. In the telecom industry, resiliency is prioritized because there are millions of dollars in losses following power outages (Anderson et al 24). This calls for the need to develop grid systems that are resilient against disruptions to limit their damages and return operations of communities to normalcy within the shortest time possible. Critical power system loads such as water stations, hospitals, and street lights are extremely important to providing basic needs to communities. Today, the use of diesel generators as power backups is being replaced with renewable energy sources due to the increase in high-cost and high-impact natural disasters and a significant decline in the cost of renewable energy systems such as PVs.
There have been developments to adopt microgrids as a potential solution to the ever-increasing need for reliable and resilient power systems. Resiliency in electrical systems aims at preventing the disruption of power during power outages and the restoration of electricity supply as fast as possible to mitigate adverse impacts of the outages (Anderson et al 24). The distributed systems of power generation using microgrids offer a solution in the development of a resilient and sustainable power system. Additionally, microgrids based on renewable energy sources offer several advantages, including flexibility, emission reduction, and economic benefits (Gielen 38). Since microgrids can either be independent or joined to the main grid, they are frequently used to serve critical loads such as hospitals in the events when the utility power has been disrupted. Interruptions to the fuel supply in many natural disasters and a decline in the cost of renewable energy systems have increased a renewed interest in the use of microgrids for sustaining critical loads and for an economic benefit during outages. Contrary to diesel generators that sit idle most of the time, renewable energy systems and demand management approaches can be adopted for economic benefits during 99% of the time when the grid is functional (Anderson et al 24). Microgrids connected to the main grid include a reduction of peak demand charges, offsetting of bulk energy expenses, performing energy arbitrates, and offering ancillary services. According to Pasonen and Hoang (13), using appropriate controls and inverters, the systems can be islanded to form a microgrid in sustaining critical electrical loads during grid outages.
Challenges in Implementing Microgrids
While microgrids have increasingly been adopted as a solution to the failures in the main grid, they often face similar risks of disruption (Chen et al 1). Therefore, it is critical to limit the performance degradation from such events and ensure minimal restoration time. There are several challenges related to the implementation of microgrids to improve resilience in power systems, including technological, political, environmental, economic, and social factors (Akinyele, Belikov, and Levron 15). These challenges have led to Akinyele, Belikov, and Levron (1) to propose the STEEP model that is focused on addressing the social, technical, economic, environmental, and political issues surrounding the effective implementation of microgrids. The STEEP model outlines the key elements and the necessary actions required to address the challenges leading to the failure in microgrid implementation, particularly in remote areas. A thorough understanding of these elements is critical in addressing the challenges and improving the situation which can lead to widespread and sustainable applications to communities around the world who live off-grid.
* Technological
The first challenge is based on the source or technology of microgrids. Most microgrids are based on renewable sources of energy such as solar photovoltaics (PV) and wind turbines (WT) (Kumar and Bhimasingu 1). The generation of energy from PV and WT is largely uncertain because the availability of solar and wind energy is unpredictable. The second technical pitfall is that there are various possibilities of power disruptions that need to be considered when designing and implementing a power-resilient strategy. Microgrid design, modeling, planning, and implementation differ from those of conventional diesel or petrol-powered systems (Lee et al.,1). Poor design of these systems can impede the effective implementation of microgrids as well as their lifespans. Thirdly, in microgrids, power generation and storage capacities are more restricted compared to a centralized generation. Lastly, in distributed energy sources, power outputs require dynamic updates at various intervals in an event of disruption. If the standard maintenance procedures are lacking, such as corrective and preventive measures, the sustainability of microgrids can be affected. The performance of solar PV systems is impacted by wiring losses and dust in addition to ambient temperature and solar irradiance factors. Other technological factors that impact the implementation of microgrid include lack of monitoring systems, insufficient knowledge of renewabl...