Page - 117 - in Clean Water Using Solar and Wind - Outside the Power Grid

© 2019 The Author. This is an Open Access book chapter distributed under the terms of the Creative Commons Attribution Licence (CC BY-NC-ND 4.0), which permits copying and redistribution for non-commercial purposes with no derivatives, provided the original work is properly cited (https://creativecommons.org/licenses/by-nc-nd/4.0/). This does not affect the rights licensed or assigned from any third party in this book. The chapter is from the book Clean Water Using Solar and Wind: Outside the Power Grid, Gustaf Olsson (Author). doi: 10.2166/9781780409443_0117 Chapter 10 Handling variable production “Nature is an endless combination and repetition of very few laws. She  hums  the old well-known air through innumerable variations.” Ralph Waldo Emerson, author, 1803–1882. It is important to keep in mind that the maximum capacity of solar PV or wind turbines (expressed in kW or MW) is seldom achieved. Solar PV can only produce when there is sunlight and wind towers can only deliver power when the wind is blowing. From the user’s point of view, the delivered useful energy (in kWh or MWh) is the interesting information. This is why the concept of “real” power and energy delivery is essential. Solar PV and wind energy sources have an intermittent production. Solar PV production can change in a few seconds if clouds or precipitation limit the availability of solar radiation for conversion to electric power. Wind speeds can change significantly in only minutes. Unlike conventional power generating systems like hydropower, renewable production cannot be adjusted to demand. The power delivery from nuclear- or coal-powered thermal plants is predictable and is determined by the system operator. In contrast, renewable energy sources have a production completely independent of the demand. To Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user