Don’t Oppose Large Dams: Hydro Power is Necessary for Solar Power to Succeed!

India has a long history of opposition to the construction of large dams. The opposition to the Saradar Sarovar project in the form of Narmada Bachav Andolan and the opposition to the Tehri dam are some of the most notable ones. There is opposition to even smaller dams and associated hydroelectric power. The reasons for this are many, the most prominent being the displacement of people and the destruction of the ecosystem. The proponents of the dams highlight the advantages: flood control, irrigation, and electricity.

However, there is one point that both sides miss completely: Opposing large dams is equivalent to opposing solar power and supporting ever increasing coal mining. Here’s why:

The growing economy of India is hungry for electric power. Electricity generation increased from 744 TWh in 2006 to 1401 TWh in 2016, an increase of 88.3% [1]. Quite predictably, during the same period, coal consumption increased by 88% [1]. In fact, the demand for coal could not be satisfied with domestic production, and as a result, the import of coal increased 5 times from 2006 to 2016. During the same period, hydroelectricity consumption increased by just 14% [1]. Moreover, natural gas production in India shows a worrying trend, declining from 29.3 BCM in 2006 to 27.6 BCM in 2016 [1]. In short, it is coal that supports the rising economy of India. Unless solar power can somehow replace the electricity produced using coal, coal mining is only going to increase.

Solar Power Needs Hydroelectricity:

The resource with the highest potential to produce electricity is solar, more specifically photovoltaic electricity. However, this resource is an intermittent but predictable resource. A 1 MW solar power plant will not produce 24 MWh of electricity in a day. In fact, the long term average is likely to be only about 4.25 MWh/day [4], depending on the location of the plant. Thus, solar power either needs a backup or some type of storage to cover the time when the sun is not shining or shining not very brightly. When solar power is not available, the backup source needs to take over. This is best explained with a load curve aka load profile. The figure below shows an ideal theoretical load curve [see note at the end] for the state of Maharashtra in India:

The red line shows the load (demand) on the grid. It can be observed that in an ideal situation, load on the grid corresponds to human activity. The demand is at its lowest from 1 AM to 4 AM. There are two peaks in the demand, one at noon and another at about 8 PM in the evening. It can be observed that solar power, if it were installed, can fulfil the demand as it rises in the morning. Solar power is not available in the evening or at night. The demand in the evening and night can be fulfilled by hydro power and natural gas. A small amount of base load can be served by coal or nuclear power. In such an ideal scenario, solar power can fulfil about 45% of the total electricity demand, hydro power and natural gas would serve about 37% and coal/nuclear power will fulfil about 18% of the demand. This is without any type of storage of electricity. Development of either pumped hydro storage or other modern storage solutions can help solar power serve an even higher percentage of the total electricity demand.

Large scale storage solutions are still very expensive and using a backup power source is the most viable option. A backup power source needs to be dispatchable, meaning it should be possible to turn it on or off on-demand and the output power should follow the demand from the grid. Electricity from coal or nuclear power is not very dispatchable. The best resources from this perspective are hydroelectricity and natural gas. However, potential for natural gas in India seems rather bleak, with production on the decline in the past few years. Considering this, hydroelectricity is the only viable resource that can serve as backup for solar power.

Hydroelectricity Potential in India:

India has a hydro power potential of 146 GW at 60% load factor [2]. Thus, in a year, 767 TWh of electricity can be generated using hydroelectric power stations. This number does not take into account the potential for pumped storage hydro power, the potential for which is about 90 GW [3]. Total electricity generation in India in the year 2016 was 1401 TWh. Thus, fully realising the hydroelectric potential in India could easily support 55% of generation. More importantly, 1 unit of hydro generation supports more than one unit of solar generation by taking over when solar power is not available. Availability of pumped storage hydro power and with some support from natural gas based power stations, solar power can serve more than 50% of the total electricity requirement. In the absence of support from hydroelectric power, solar power cannot succeed since coal or nuclear power will not be able to serve as a viable backup when solar power is not available. By realising the full hydroelectricity potential, solar power can can grow and provide more electricity than hydro.

Conclusion:

Opposing dams is a folly. They are absolutely necessary for solar power to succeed and to avoid all the damaging effects of using coal as the primary source of electricity. Large dams do have their disadvantages. However, those disadvantages must be weighed against the environmental benefits of moving away from coal as the primary source of electricity.

Note on load curve: The actual load curve for Maharashtra is quite flat with only a small dip in the night. The load curve discussed above was for an ideal situation. Presently, the grid is mostly powered by coal and these power stations are not very good at handling a load curve that corresponds to human activity. As a result, electricity consumers are forced or provided with an incentive to use power in the middle of the night. While such staggered usage of electricity is necessary for coal power, it takes a toll on farmers and workers who are forced to work at odd hours. Using solar power in conjunction with hydro power and natural gas will allow the load curve to resemble human activity. Incentives for working in the night will no longer be necessary, In fact, incentives may be provided to work more during the daytime. A large number of farmers and workers will benefit from this.

References:

1. BP Statistical Review of World Energy 2017: BP
2. http://powermin.nic.in/en/conten…
3. India Wants to Build 10 Gigawatts of Pumped Hydro Storage to Support Solar
4. How much energy does a 100W rooftop solar panel generate?