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Optimal Electrification Planning Incorporating On- and Off-Grid Technologies: The Reference Electrification Model (REM)
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| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 107 (No. 9) |
| Halaman | : | 1872-1905 |
| Abstrak | : | In many parts of the world, access to basic electricity services remains a significant challenge. The status quo mode of electrification is central grid extension; however, in many areas, off-grid (OG) technologies like minigrids (MGs) and standalone (SA) systems are more suitable for promoting electricity access under cost constraints. Unfortunately, these opportunities are often overlooked due to the complexities of electrification planning, especially for large areas. Researchers have designed technoeconomic planning tools that can be scaled to cut through aspects of this complexity and be fit to address different places and contexts. This paper describes a computer-based optimization model - named the reference electrification model (REM) - which performs automatic electrification planning and is able to identify lowest cost system designs to most effectively provide desired levels of electricity access to populations of any given size. In doing so, REM determines the most suitable modes of electrification for each individual consumer by specifying whether customers should be electrified via grid extension, OG MGs, or SA systems. For each system, REM supplies detailed technical designs at the individual customer level. We have used this model in real planning activities in sub-Saharan Africa and South Asia. The description of REM's capabilities is supported by case examples. REM stands apart from other electrification planning models because of its high granularity and its capability to provide concrete plans for a wide range of geographical scales. Because of these benefits, REM has the potential to help rationalize electrification planning and expedite progress toward universal electricity access worldwide. |
Devices and Fibers for Ultrawideband Optical Communications
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 110 (No. 11) |
| Halaman | : | 1742-1759 |
| Abstrak | : | Wavelength-division multiplexing (WDM) has historically enabled the increase in the capacity of optical systems by progressively populating the existing optical bandwidth of erbium-doped fiber amplifiers (EDFAs) in the C -band. Nowadays, the number of channels—needed in optical systems—is approaching the maximum capacity of standard C -band EDFAs. As a result, the industry worked on novel approaches, such as the use of multicore fibers, the extension of the available spectrum of the C -band EDFAs, and the development of transmission systems covering C - and L -bands and beyond. In the context of continuous traffic growth, ultrawideband (UWB) WDM transmission systems appear as a promising technology to leverage the bandwidth of already deployed optical fiber infrastructure and sustain the traffic demand for the years to come. Since the pioneering demonstrations of UWB transmission a few years ago, long strides have been taken toward UWB technologies. In this review article, we discuss how the most recent advances in the design and fabrication of enabling devices, such as lasers, amplifiers, optical switches, and modulators, have improved the performance of UWB systems, paving the way to turn research demonstrations into future products. In addition, we also report on the advances in UWB optical fibers, such as the recently introduced nested antiresonant nodeless fibers (NANFs), whose future implementations could potentially provide up to 300-nm-wide bandwidth at less than 0.2 dB/km loss. |
Distributed Resources Shift Paradigms on Power System Design, Planning, and Operation: An Application of the GAP Model
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 107 (No. 9) |
| Halaman | : | 1906-1922 |
| Abstrak | : | Power systems have evolved following a century-old paradigm of planning and operating a grid based on large central generation plants connected to load centers through a transmission grid and distribution lines with radial flows. This paradigm is being challenged by the development and diffusion of modular generation and storage technologies. We use a novel approach to assess the sequencing and pacing of centralized, distributed, and off-grid electrification strategies by developing and employing the grid and access planning (GAP) model. GAP is a capacity expansion model to jointly assess operation and investment in utility-scale generation, transmission, distribution, and demand-side resources. This paper conceptually studies the investment and operation decisions for a power system with and without distributed resources. Contrary to the current practice, we find hybrid systems that pair grid connections with distributed energy resources (DERs) are the preferred mode of electricity supply for greenfield expansion under conservative reductions in photovoltaic panel (PV) and energy storage prices. We also find that when distributed PV and storage are employed in power system expansion, there are savings of 15%–20% mostly in capital deferment and reduced diesel use. Results show that enhanced financing mechanisms for DER PV and storage could enable 50%–60% of additional deployment and save 15 $/MWh in system costs. These results have important implications to reform current utility business models in developed power systems and to guide the development of electrification strategies in underdeveloped grids. |
Ultrawideband Systems and Networks: Beyond C + L-Band
| Pengarang | : | Takeshi Hoshida |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 110 (No. 11) |
| Halaman | : | 1725-1741 |
| Abstrak | : | In the evolution of optical networks, spectral efficiency (SE) enhancement has been the most cost-efficient and thus the main driver for capacity increase for decades. As a result, the development of optical transport systems has been focused on the C - and L -bands, where silica optical fiber exhibits the lowest attenuation, and erbium-doped fiber amplifiers provide an efficient solution to compensate for the optical loss. With a gradual maturity in the SE growth, however, the extension of the optical bandwidth beyond the C+L -band is expected to play a significant role in future capacity upgrades of optical networks and, thus, attract increasing research interests. In this article, we discuss the merits and challenges of ultrawideband optical transport systems and networks beyond conventional bands. |
Least-Cost Electrification Modeling and Planning—A Case Study for Five Nigerian Federal States
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 107 (No. 9) |
| Halaman | : | 1923-1940 |
| Abstrak | : | Nigeria is the African country with the highest total number of people without access to electricity, at least 90 million. To provide sustainable and affordable energy to these people is an enormous challenge. Advanced modeling and planning are essential tools to enhance the quality of investment decisions. Planning has to address the latest electrification options [grid extension, hybrid minigrids, and solar home systems (SHS)] in a technically and economically sound way for different implementation phases. We have developed a modeling process to derive a least-cost electrification plan for five federal states in Nigeria combining energy system simulations with geospatial information system tools. Investments of approximately $1600 million for medium-voltage (MV) and low-voltage distribution infrastructure, minigrids, and smallscale systems are required to achieve a 100% electrification rate. The simulated electricity system of the five states is characterized by an overall load of about 1804 MW. The electrification options comprise different electrification measures. About 1772 MW are supplied by central power generation through the central grid via 11579-km new grid lines. The decentralized supply sources include only a few renewable energy (RE) minigrids with a total of 3-MW load will remain isolated, while all others will be interconnected to the central grid. The decentralized supply is defined by 225-MW photovoltaic (PV), 504-MWh battery, and 198-MW diesel-based isolated and interconnected minigrids as well as by 29-MW SHS capacities. |
Flexible Technologies to Increase Optical Network Capacity
| Pengarang | : | Andrew Lord |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 110 (No. 11) |
| Halaman | : | 1714-1724 |
| Abstrak | : | Increased global traffic puts tough requirements not just on fiber communications links but on the entire network. This manifests itself in multiple ways, including how to optimize wavelength routing around the network, how to maximize the benefits arising from fine-control DSP with increasingly accurate real-time monitoring, and how to best deploy multiband or multiple fiber connectivity. This article will summarize research into all these areas to present a full picture of how future optical networks will play their role in supporting the continuing traffic demands of broadband, 5G, and associated applications. |
Challenges in Estimating the Information Capacity of the Fiber-Optic Channel
| Pengarang | : | Mark Shtaif |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 110 (No. 11) |
| Halaman | : | 1655-1678 |
| Abstrak | : | Since its early commercial deployment in the late 1980s, optical fiber has evolved to become the predominant carrier of the globe’s communications. Yet, after accommodating the world’s exponentially growing appetite for transmitted data for more than three decades, its ability to continue doing so is being challenged by fundamental factors. In this article, we review these factors and examine their consequences in terms of information capacity. In particular, we review the difficulties that are imposed by the nonlinear nature of fiber-optic transmission on the assessment of the capacity and on the definition of fundamental concepts, such as bandwidth and spectral efficiency. We discuss relevant approximations and regimes of operation in which bounds for the capacity can be effectively assessed while covering a broad range of applications ranging from interdatacenter communications to links spanning transoceanic distances. We relate to a broad variety of transmission schemes and discuss the potential benefits of spatial multiplexing with multimode and multicore fibers. State-of-the-art transmission experiments are also reviewed and compared with theoretical capacity bounds. |
The Service Value Method for Design of Energy Access Systems in the Global South
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 107 (No. 9) |
| Halaman | : | 1941-1966 |
| Abstrak | : | This paper presents the service value method (SVM) as a novel means to gather and interpret end-user needs, aspirations, and contextual factors to improve engineering design practice of energy access systems for the Global South. The method adopts a service-oriented approach and consists of a rapid and effective field exercise to gather qualitative and quantitative data from end users in focus groups. This exercise is suitable for enabling end-user participation in Global South contexts. The data are interpreted as service maps that capture end-user preferences to inform tradeoffs of different design criteria, guiding the preliminary design of the energy system. The method ensures end-user needs and contexts are integrated into the design process early on. A case study is presented, where the SVM was used to design solar nanogrids in Kenya and Bangladesh. |
Electrical Minigrids for Development: Lessons From the Field
| Pengarang | : | Alexander P. Parobek |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 107 (No. 9) |
| Halaman | : | 1967-1980 |
| Abstrak | : | Energy services are crucial to human wellbeing and development, and without reliable energy, it is difficult to escape subsistence lifestyles and poverty. Here, we report on four identical capacity rural minigrid interventions undertaken in Kenya and Uganda with differing socioeconomic characteristics and demographics. The research outcomes presented briefly discuss the preparation stages of the interventions including community surveys that informed the technical design, deployment phases, and setup of the community cooperatives to manage the minigrid projects. The main focus here is on lessons learned, including system design and minigrid performance under various load profiles. The results show a clear and increasing uptake of power by the communities with intensities varying depending on the electricity tariff used. Across the four minigrids, daily electricity growth rates are seen to vary by a factor of 8. The Ugandan minigrids operated at close to utility grid tariff and reached the 28-kWh/day design limit within two years. By contrast, the Kenyan minigrids charged a higher cost recovery tariff, which capped the demand and systems operate below the design limit. These findings have implications not only to system design but also to system stability and longevity. The approach taken here, of community centered cooperatives running the delivered minigrids, is now embedded within the rural electrification authorities/agencies in both countries, with additional similar projects being planned in 2019/2020. The application, ramifications, and replication of such a minigrid concept as compared to other approaches are also discussed in this paper. |
Electrification Processes in Developing Countries: Grid Expansion, Microgrids, and Regulatory Framework
| Pengarang | : | - |
| Nama Majalah/Jurnal | : | Proceedings of the IEEE |
| Volume / Edisi | : | 107 (No. 9) |
| Halaman | : | 1981-1994 |
| Abstrak | : | Shortages and poor diversification of generating capacity, high environmental impacts, and low qualities of supply and affordability are common characteristics of the electricity sector in most developing countries (DevCs). Recent cost reductions in the telecommunication sector and some generation technologies, especially renewable-based, with improved economic feasibility have paved the way for new electric infrastructures. This is especially true for emerging economies, as locally dispatched hybrid microgrids introduce flexibility and show the promise of technical and economic advantages. The design and integration of microgrids require detailed assessments to ensure the effective deployment of capital to minimize the risk of stranded assets and capital waste. Microgrids can be considered an affordable option for a rapid response to the electrification challenge, recognizing that, in the longer horizon, a sharing of resources with the bulk electrical power system will remain, technically and economically, advantageous. This article presents a comprehensive review of the approaches commonly adopted for microgrid electrification. A “real-life” study case is reported to highlight the operational challenges of a stand-alone microgrid versus a grid-connected system. The need for an improved regulatory framework is presented as the cornerstone problem to be solved to allow an effective integration of microgrids in the national grid. |