Pros & Cons of Mini Hydropower Plants

While the first time that moving water allowed to produce electricity occurred more than a century ago, in 1882, on the Fox River in Wisconsin, hydropower has always had a significant role in the expansion of the electricity among the world population. After all, hydropower remains as one of the most valuable renewable energy resources, and they represent a non-polluting, a non-radioactive, and a non-consumptive use of water resources.

A major discussion that we have been watching in the last couple of decades relates to the size that hydropower dams should have. The truth is that even though hydropower has a lot of benefits, it also has some drawbacks, especially in what concerns with the environmental effects and social displacements that it can cause. So, more and more researchers are looking for ways to produce hydro power without affecting the environment.

One of the thing that is being discussed is the use of micro-hydro power plants in irrigation canals.

So, what are mini-hydro power plants?

Simply put, a mini-hydro power plant is one of the many kinds of hydroelectric power that are usually able to produce up to 200 kW of electricity per turbine, only using the natural flow of the water.

Whether in small rural community or just for a single remote household, a mini-hydro power plant can be the perfect solution to provide electricity to people. This is just what happens in Japan, with the Momura mini-hydro power plant.

Just like hydro power dams have advantages and disadvantages, and these can vary depending on you’re considering big or smaller dams, mini-hydro power plants also have their pros and cons.

Mini-Hydro Power Plants Pros:

1: High Plant Factor

There’s no question about the efficacy of micro hydropower, particularly when it comes to plant factor. This concept shows the relationship between how much power a plant could technically produce and the amount it actually generates. A Turbulent micro hydro power plant can have up to 90% plant factor. In comparison, the average solar panel array has a plant factor of 10%-30%. As a result, throughout the year a solar panel array generates less than a quarter of the power it is capable of. This means that on the long term, a micro hydro power plant can save up to 37% of the costs of a similar solar installation.

2: Reliability

When you compare the hydro energy with other renewable energies, it won’t be hard to notice that hydro is one of the few that produces a continuous supply of electrical power. Plus, one of the main advantages regarding hydropower is the fact that it is more needed during night and the winter months and this is when exactly large quantities of electricity are produced.

3: No Reservoir Needed

One of the main problems that have been pointed out by researchers when considering the environmental effects of larger dams is the release of chemicals from the water reservoir. However, this won’t occur when using a mini-hydro power plant in irrigation canals.

The mini-hydro is mainly seen as a function that next to the river. The water will only pass through via a bypass canal to the turbine, but it will be directed back into the stream. This guarantees that the impact on the surrounding ecology will be minimum.

4: Cost Effective

The reality is that the difference between the expenses of building a larger dam and a smaller dam is already huge. However, when you consider the costs of building a mini-hydro power plant, this is, by far, the most affordable solution.

Depending on the location as well as on site electricity requirements, a small mini-hydro power plant can cost between €80 000 and €400 000. This cost would be usually divided by the amount of households benefiting from the electricity.

In example, if the energy consumption of an average household in a remote community is 1000 kWh, around 1750 households can have continuous energy with a 200 kW turbine, making the cost for the whole system (including grid, civil works) for a couple of hundred euros per household, already a huge decrease in expenses. The maintenance fees will also be a lot smaller than the maintenance costs of dams, either big or small, as well as than other technologies.

5: A Scalable solution

As a scalable solution, a single Turbulent turbine can generate up to 200 kW. But what if you need more power? As long as the river has enough flow and drops downstream, you can installed an interconnected network of turbines to generate up to multiple megawatts. Not only that, but the turbine can also be connected to other renewable energy systems as well as to the local grid to create hybrid electrical local networks.

6: Great Help For Developing Countries

Developing countries don’t have the same budgets as developed countries. However, they do have the same small villages and communities that they need to make sure have electricity. So, with fewer costs, the mini-hydro power plants for irrigation canals can be a great option.

7: Integration With The Local Power Grid

One of the main advantages, when you decide to invest in a mini-hydro power plant for canals, is the fact that, most probably, it will produce too much energy. So, you can get power companies to buy back your energy overflow.

Mini-Hydro Power Plants Cons:

1: Requires Specific Site Characteristics

To take full advantage of the mini-hydro power plant in irrigation canals, you need to make sure that you have the right site. Some of the factors that you will need to take into account include the stream size (including the height difference and flow rate), the distance between the mini-hydro and the location of the canals, and the balance of the system components, pipelines, transmission lines, controllers, batteries, and inverter.

2: Summer Months May Be A Concern

In many locations, the stream size varies depending on the season. Usually, summer months tend to present less water flow which results in less energy produced. This is why it is important to know if all the energy requirements are going to be met during the entire year during the planning and research stages.

Summing all up, there’s no question that mini-hydro power plants can be extremely helpful in irrigation canals, rivers, outflows from hydroelectric plants or water treatment plants. Besides the fact that this is a great source of clean energy, it is both reliable and cost-effective. The truth is that the problems that can come up with the construction of mini-power plants can all be avoided if there are a good planning and research. The environmental impacts will be inexistent which makes it one of the best alternatives for rivers and canals.

Read about Turbulent in Green School Bali case study, part of the UNIDO's World Small Hydropower Development Report (page 70).