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India has installed power capacity of over 400GW and has declared itself a nation of surplus power. Yet, the official website indicates that the country also imports hydro power from Bhutan and Nepal. Is this just a case of hydro diplomacy or are the North eastern regions of India easily connected to the Bhutanese and Nepali grids ?

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    If there is a political question here (not just supply/demand at work) it needs preliminary research... for starters India is a net exporter of electricity to Nepal and sometimes exports to Bhutan as well. pib.gov.in/PressReleasePage.aspx?PRID=1607177
    – Brian Z
    Commented Dec 15, 2022 at 14:31
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    This is simply a cost optimization. Hydro energy is often more like a big, self-recharging battery than a normal powerplant: extracting energy at full power runs your reservoirs dry rather quickly. Thus it is cheaper for the Hydro-nation to buy energy whenever it is cheap (=> net import), while spinning up the hydro power only when demand (price) is very high (maybe just for a few hours per day, or whenever other plants/renewables are down). This way, a lot less non-hydro plants are needed overall AND they can always run full-tilt, which is a win/win on cost.
    – radioflash
    Commented Dec 16, 2022 at 13:47
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    Probably not as important in India, but Germany has imported AND exported a lot of power from/to nordic countries at the same time, for quite a while. This is because German electricity providers have sold "green hydropower energy" contracts to end users at a premium, exported German nuclear electricity to Scandinavia, imported hydropower energy from there for a fraction of a cent more, and sold that for much more than a cent more. Being a net exporter does not mean you always export. Commented Dec 16, 2022 at 21:04

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Not all ways to generate electricity are equal.

  • Some kinds of power are very dependent on time and weather (solar, wind and, surprisingly, nuclear power plants which sometimes need to throttle down when the weather is too warm due to cooling problems)
  • Some kinds of power are more reliable, but need hours to increase or decrease their output, so they can't compensate sudden spikes (coal, nuclear)
  • Some kinds of power are able to regulate up and down quickly, but are expensive (gas)
  • Some kinds of power might be able to provide power quickly, but might be bound to some natural reservoir that might run out and take some time to replenish (hydro)
  • The ability of power grids to transfer power over long distances is limited. Which means that in a country as large as India, you have to take a more regional look at the economics of electricity generation and consumption. When there is a lack of power in Assam, then getting it from Bhutan might be more efficient than getting it from Rajasthan. (Just an example. I am not actually familiar with the power grid of India, so I am not sure if this is a realistic scenario)

The result is that even countries which on-paper have more than enough capacity to fulfill their needs and are "net exporters" of energy when looking at longer time frames will from time to time import energy from neighboring countries.

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    The last bullet point (conceptually anyway) is definitely true. Loss of power in transmission is mostly a function of voltage (the lower the voltage the greater the loss) and distance, and the two factors are independent of each other for all practical purposes. There is another factor too. Transmission and distribution losses in India are nearly 30 percent (v. 2-13% in various U.S. states), in part due to electricity thieves. insideenergy.org/2015/11/06/…
    – ohwilleke
    Commented Dec 15, 2022 at 20:39
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    An Assam government report notes (my bolding): "The State is facing high energy and peak deficits. [...] The total installed generation capacity available to the State including Central Sector allocations and Bhutan power projects is expected to reach 2,531 by FY19 (contributed mostly by NEEPCO at 679 MW followed by allocations from power plants from Bhutan at 500 MW) which can cater to a peak demand of 2,174 MW."
    – njuffa
    Commented Dec 16, 2022 at 3:38
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    It is also about the way the electricity is consumed. If TV commercial starts during some sport event, people might actually go and make a tea. Suddenly you have millions of kettles pushing grid to the limits. This is especially true in the UK, but you get the idea. Commented Dec 16, 2022 at 12:22
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    "Loss of power in transmission is mostly a function of voltage", that's true. It's just there is certain threshold where increasing voltage is no longer feasible. An example is Ekibastuz–Kokshetau power line which runs on a ultra high voltage of 1150kV. It faces some challenges due to corona discharges. If you increase voltage, you reduce the Ohm's law loses, but also at the same time increase loses due to corona discharge. Commented Dec 16, 2022 at 12:26
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    Even if there were no transmission losses, transmission isn't necessarily transitive. Just because A could buy from B and B could buy from C doesn't mean A can buy directly from C.
    – chepner
    Commented Dec 16, 2022 at 18:55

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