Improving Lives of Rural Communities Through Developing Small Hybrid Renewable Energy Systems

• Publisher: Asian Development Bank
• Year: 2017
• ISBN:
  9789292579326
• Topic: Technik & Maschinenbau
• Subtopic: Regenerative Energieressourcen

Despite significant economic growth in Asia in recent decades, millions of people in rural Asia still lack access to electricity. A project has been implemented to develop small hybrid renewable energy systems in these areas. This publication highlights the experiences of these pilot projects in five developing member countries. It provides technical guidance and recommendations for the deployment of similar systems in minigrids in remote rural locations and small isolated islands to achieve access to electricity and energy efficiency.

PILOT PROJECTS

The six pilot projects developed under the TA brought substantial tangible benefits to local communities, improved their livelihood, and resulted in lessons learned from implementation of these projects. These benefits and lessons learned are briefly discussed in each relevant case study below.

Bangladesh Subproject: Compact Photovoltaic–Battery Storage Power Plant in Siddhirganj

Background

The 36-kilowatt-peak (kWp) Siddhirganj solar photovoltaic (PV) plant demonstrates two innovative approaches to project development: (i) a containerized plug-and-play installation that delivers power to a school during the day (the anchor consumer), and (ii) utilizing capacity more efficiently by distributing the surplus power to nearby settlements.

The school chosen to host the project is located 25 kilometers southeast of the capital Dhaka and experienced constant power outages. To address the situation, the Bangladesh Power Development Board designed the project to gain autonomy from the grid, subject to budgetary constraints and rooftop space limitations.³

In addition, the school was the location best suited to raise awareness among the students and visitors. The TA contributed the project hardware and technical expertise for design and implementation. The scope of the project was expanded to supply surplus power to the nearby residences.

While solar resource at the site was known to be stable and predictable for most months of the year, the average wind speeds in the area were found to be too low and generally inadequate for small wind turbines to generate power at the site.

Implementation

The project comprises 36kWp alternating current (AC)-coupled solar PV systems and 120 kilowatt-hours (kWh) of lead-acid battery storage units (providing consumers with 3-day “no-sun” autonomy). Although lithium-ion batteries have significant advantage of having nearly 10 times more recharge cycles than lead-acid batteries, the latter was nevertheless chosen in the design for its low maintenance cost. The system was designed to meet a projected average daily demand of 151kWh and a maximum demand of 192kWh per day. The projected annual power generation of 59,580kWh was intended to meet close to 80% of the annual demand at the school.

Compact Hybrid Power Plant at Power Development Board High School, Siddhirganj, Narayanganj, Electricity Company Bangladesh Limited.

Source: Electricity Generation Company of Bangladesh.

Experience

The electrical fans, lights, and computers were projected to consume about 25kWh during each school day. Over the 206 days between plant commissioning on 25 February and 18 September 2016, the school was operational for 120 days (approximately 60%), with the 86 days accounting for weekends and the Ramadan vacation. Over this period, the school consumed 5,035kWh of power, or about 42kWh each school day.

Early experience with implementing and operating the Siddhirganj PV project yielded a few valuable lessons:

(i) Mobilizing the community during the planning and implementation stages helps build goodwill for the project.

(ii) Involving local residents and technicians during project implementation (and having them collaborate with the equipment vendors) helps residents understand the design and also builds local operation and maintenance (O&M) capacity.

(iii) The power plant is designed to meet aggregate consumption demand but needs to be optimized to meet hourly and weekly demand through appropriate charge–discharge of the battery, supplying anchor loads over weekends.

(iv) Compatible and efficient appliances, such as lamps and fans, could be procured simultaneously to inculcate efficient utilization of power generated by the plant from the very beginning.

(v) Building local capacity and maintaining inventory of crucial spares on-site serve to ensure uninterrupted plant operations and service provision.

Maldives Subproject: Solar–Battery Storage and Diesel Hybrid Energy System on Rakeedhoo Island

Background

Rakeedhoo Island in the Vavoo Atoll of the North Central Province of Maldives is located 96 kilometers north of the capital, Malé. It faced a unique set of circumstances. The government census of 2006 counted a total population of 158 on the island including 69 men and 89 women, with near total literacy and with roughly half the total population within the 26–64 age group.⁴ By mid-2014, when the project was designed, the island had over 370 registered inhabitants but only about 90 residents. Given the paucity of educational opportunity and economic activity on the island, people had left in search of opportunity elsewhere.

Previously, the island was supplied by three diesel generators of varying vintage: two 40 kilowatts (kW) and one 60kW. The project was therefore designed to optimize the generation mix to promote ecotourism on the island, as a means of expanding economic opportunity while mitigating emissions, lowering unit costs, and enhancing reliability.

Project design was compounded by the challenge of meeting mean power demand during most parts of the year, as well as of supplying power to meet peak demand when all the 370 inhabitants (and possibly more) arrived on the island.

Implementation

Wind resources on the island were assessed to examine the prospect of installing micro or small-wind turbines. The optimal microgrid was to incorporate solar PV arrays, and lithium-ion battery storage, with the existing diesel generators serving to meet peak loads.⁵

Power demand on the island was estimated at 173kWh, and the solar PV arrays were slated to provide 129kWh to meet demand simultaneous with generation during the sunshine hours. The battery storage units were sized to balance between surplus generation and peak demand.

The project is implemented jointly by ADB and the State Electricity Company (STELCO), the electricity utility in charge of generating and distributing electricity in Maldives. Project equipment was procured on the basis of a competitive bidding and included supply, installation, and commissioning.

The design included solar PV, lithium-ion battery bank, and diesel generators. The proposal to install a small wind energy generator was shelved because of inadequate wind resource availability on the island. In coordination with STELCO, ADB procured the equipment for the pilot project, and recruited consultants to help with the resource assessments, design, capacity building, and other aspects of implementation. The project is operated and maintained by STELCO with inputs from the equipment supplier. The consultants and equipment suppliers provided hands-on training to STELCO counterpart staff on installation, testing, and O&M of the hybrid renewable energy system.

The energy system comprises 29kWp AC-coupled solar PV arrays, operating in tandem with the existing two 40kW and one 60kW diesel generators, 2kW (3-phase) inverters, and 60kWh lithium-ion batteries for power storage.

Experience

In mid-2014, when the system was designed, the aggregate load on the island was estimated to be 173kWh and design simulations showed that power from the solar PV arrays could meet about 82% of this demand while reducing dependence on the diesel generators. However, by the time the project was commissioned in mid-2016, the typical daily load had increased to 487kWh, while frequently exceeding 500kWh. This demand is met through continuously operating the existing diesel generators to supplement power from the PV system.

As depicted in Figures 1 and 2, during the early stages of project operation in 2016, the power produced from the 29kWp solar PV array fell within a wide range—between 18kWh and 163kWh—with a daily average of about 100kWh. This was lower compared with the...