Micro-Grid in Developing Countries
Power Transmission and National Grids:
A traditional power system network consists of a power generation unit, transmission conduits, and retail distribution. The end user receives electricity after a series of changes in the voltage levels in the transmission system or the power grid. So far, the power grid, which is also known as the national grid in many countries such as Bangladesh, is considered as a network which connects different part of a country or a region. The grid connects the end user to the central power source, allowing it to operate appliances, electronics, lighting, and machines.
Despite increasing demand for electricity everywhere, the expansion of the national grid may not always be an option due to the higher per unit cost of the transmission to the remote areas of developing countries and due to the inherent security vulnerability of the grid. A Micro-Grid is a viable option that solves both aforementioned concerns. Currently, many communities in the developed countries have built self-supporting micro-grids that also earn revenue by selling excess capacity to the national grid.
Role of Micro-Grids:
Micro-Grids are proving to be a viable option due to the availability of more affordable technology for generation of renewable energy. For example, a single wind turbine can now generate up to 4 megawatts of electricity compared to only 2 megawatts just a decade ago. And while solar energy was one of the most expensive forms of power generation, the cost of solar panels has come down significantly over the last decade.
A Micro-Grid is a local energy production unit with control capacity, i.e., it can operate autonomously without being connected to a traditional grid. In general, a Micro-Grid is connected to the national grid, but it is important to emphasize that it can independently operate on its own during natural calamities, power outages, or all the time.
A Micro-Grid can be powered by a traditional generator, batteries, or by solar panels. It can connect (or also can work off-grid) to the grid at a point of common coupling, that maintains the voltage at the same level as the main grid, except for disruptions in the connection flow. A simple switch can disconnect the Micro-Grid from the national grid allowing it to operate independently as a stand-alone unit.
A Micro-Grid not only provides backup for the grid in case of emergencies but can also cut costs for the local area that is either too remote or not cost effective to be connected to the traditional grid use. It allows communities to be self-reliant in energy and be environmentally friendly at the same time.
The main features of a Micro-Grid are:
- It is a locally controlled system
- It can function being connected to the traditional grid or as an independent unit of electricity generation (off-grid).
The operation of a Micro-Grid offers the following advantages to customers and the economy:
- Improved energy efficiency,
- Reduction in energy wastage,
- Reduced environmental impact, and
- Reliability of supply.
Micro-Grid – Bangladesh Perspective:
Bangladesh is a vast delta plain with hundreds of rivers and water bodies, making it very difficult and expensive for connecting the remote areas to the national grid. For example, getting power to remote lowlands by constructing transmission network would be exorbitantly expensive. Furthermore, most rural areas that are connected to Rural Electrification Board Grid, hardly ever enjoy uninterrupted power supply. Micro-Grids are a perfect solution as they can provide uninterrupted power supply to these rural areas.
While some residential units in remote areas have solar panels, there are many households who are prevented from access to solar panel generated power to due high costs, the dearth of access to technology, and lack of a coherent energy policy.
The Recent improvement in production scale and technology and substantially reduced the cost of solar panels required for our proposed Micro-Grids. The biggest roadblock seems to be a unified energy policy by the government. In this regard, private entities or public-private partnerships can initiate the process of establishing micron-grids in remote areas of Bangladesh.
Types of Micro-Grid:
There are two types of Micro-Grids:
Grid-Connected Solar Power Systems with Battery Backup
The local unit uses the power produced by the Micro-Grid and sells the surplus electricity to the national grid when access to the national grid is available. In the event of a power outage, the backup inverter will automatically turn on to power the critical appliances. The combination of solar energy and battery storage works seamlessly to provide power to essential appliances during an outage, working similar to an off-grid system.
The following figure shows the major elements required for the Grid-Connected system:
Off-Grid Solar Power Systems with Battery Backup
The off-grid is a stand-alone power generation unit providing electricity to a smaller community. The Off-Grid system has the following features:
- It does not transit any of the solar powered electricity back to the grid.
- It does not require an approval from the regional utility company since it will not use the utility.
- The size of battery bank can be calibrated to support the critical appliances or for the entire local unit.
The following figure shows the major elements required for the Off-Grid system:
To see the benefits of a Micro-Grid, the cost of solar energy system, we should measure and compare cost per watt-hour. It worth mentioning that initially, we may still have to charge a flat rate since end users may not see the immediate benefit of energy basis calculation.