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5.2: The Origin of Hydropower

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    Please keep in mind that Hydro-power is nothing else than converted solar power. There are many good things spanning indirectly from the energy coming from Sun. Water from oceans, seas, lakes, rivers, and even from moist soil, when heated up by solar radiation, yields water vapor that rises up and forms clouds the clouds then condensate and the water returns to the Earth surface in various forms of precipitation: as rain, snow, hail... The water that has returned to mountains and other high areas then begins its “trek” toward the oceans. On the way, it loses its potential energy. Harnessing hydro-power by us is nothing else than “capturing” this potential energy before it all dissipates.

    The “water cycle” is illustrated in Fig. \(\PageIndex{1}\), in which it is stressed that all energy that can be extracted from flowing or falling waters is actually solar power converted by Mother Nature. In the next Figure \(\PageIndex{2}\), it is shown how much radiative power our planet receives from the Sun – and how much of it is converted to hydropower that can be harnessed by us. Its almost one-half of the total global consumption of power. We still use only a fraction of those available resources – but even if we managed to harness them all, they would not satisfy all our needs. However, since there are still available hydropower resources not yet taken advantage of, it would be a wise thing to start using them. In contrast to fossil fuel resources, hydro-power resources cannot be exhausted!

    In the upper graph in Fig. \(\PageIndex{3}\) it is shown how the global population “appetite” for electric power is growing over time – and what is the contribution of different sectors of power industry to satisfying these needs.

    According to the World Energy Council, in the year 2016 the share of hydropower in global power generation was 16.4%. As indicated by predictions, this gure is not expected to change signicantly over the next 20-30 years.

    Figure \(\PageIndex{1}\): The water cycle (source: Wikimedia Commons).

    Figure 5.5:

    Figure \(\PageIndex{2}\): The total radiative power delivered to the Earth surface by Sun, and the available resources of two other forms of power, compared with the current total global consumption all all energy forms. The volume of each sphere is proportional to the corresponding power listed next to it (aop).

    In the lower graph in Fig. \(\PageIndex{3}\) it is shown how much hydropower is generated by different countries. China generates most, but if one considers how big the populations in each country is and calculates the hydropower generation per one million population, then Brazil (current population slightly over 200 million) is the unquestionable winner, and the US is also ahead of China.

    It is also remarkable that Brazil satisfies over 90% of its power needs from hydro. Norway, in which the hydro-sector satisfies 100% or even more of the country’s needs (more than 100% – how is it possible? Yes, it is, Norway exports its surplus of electric power to other countries, primarily to Denmark through an undersea transmission line capable of transmitting up to 2 GW of power).

    In the US, according to the US Energy Information Administration, the share of hydropower in the total usage is perhaps less impressible – it is about 6.5% of the total.

    Figure \(\PageIndex{3}\): Upper graph: The global production of electric power showing the share of each major technique – prediction running up to the year 2040. Lower graph: generation of electricity in hydropower plants, by countries.

    Figure \(\PageIndex{3}\): Upper graph: The global production of electric power showing the share of each major technique – prediction running up to the year 2040. Lower graph: generation of electricity in hydropower plants, by countries.

    However, in the US the share of hydropower in individual states is very the different. The graph in the page below is from the year 1995 and is no longer very accurate. Current data from individual states can be found in this Wikipedia article, or in this US Energy Information Administration Web site – in the latter, there is a map with all states and if you click on one, you get info not only about hydropower generation in it, but also a bounty of info about all other power sources in this state.

    Table \(\PageIndex{3}\) Hydroelectric generaration in 2018 in TWh: Total USA and the leading states (all other states generate less tan 5 TWh each)

    USA total






    New York














    North Carolina


    South Dakota


    Source: U.S. Energy Information Administration Detailed State Data 1990-2018 Net Generation by State by Type of Producer by Energy Source

    5.2: The Origin of Hydropower is shared under a CC BY 1.3 license and was authored, remixed, and/or curated by Tom Giebultowicz.

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