[Cz] Vodni elektrarny jsou jednim z obnovitelnych zdroju elektricke energie, ktere nevyuzivaji niceho jineho nez pohybu vody, jak je jiz z nazvu patrne. Tato energie je hojne dostupna a relativne levna, cemuz napomaha i fakt, ze vodni turbiny patri k motorum s nejvyssi ucinnosti. I presto jsou a budou vodni elektrarny jen doplnkovym zdrojem, nebot dostatecne mnozstvi energie vyprodukuji jen v oblastech s prihodnymi podminkami a takovych mist neni mnoho (napr. Norsko pokryva 90 % spotreby vodnimi elektrarnami). V soucasne dobe se odhaduje ze staly vyuzitelny vykon vodnich elektraren cini cca 3 TW.
[En] Water energy is one of the renewable power sources. This energy is relatively widely available and cheap (water motors have one of the biggest efficiency). Unfortunately, water power–plants are and will be additional power sources only because it is limited by amount of the convenient areas (e.g. Norway uses 90 % energy from the water sources). Nowadays, usable power of the water power–plants is estimated to 3 TW.
[Cz] Vodu vyuzival clovek dlouho predtim, nez vubec zjistil, co je elektrina. To se uplatnovalo predevsim ve vodnich mlynech, pilach, hamrech, cerpadlech vody samotne, ale take v mnoha dalsich oblastech, napriklad v dolech jako pohon vytahu ci vetrani. Voda nam nabizi celkem tri druhy energie – chemickou (rozpousteni cca 27 milionu tun pevnych latek za rok, vznik solnych roztoku), vnitrni (teplotni rozdil ruznych vrstev vody, ktery muze dosahovat az 20°C, ale take teplych proudu, napr. Golfskeho proudu) a mechanickou (kolobeh vody v prirode pohaneny predevsim slunecni energii).
Chemicka energie vody je prilis slaba, aby se dala rozumne vyuzivat, oproti tomu vnitrni energie je jiz dostatecna na pohon elektraren, ktere jsou ale spise tepelne nez vodni. Cistokrevne vodni elektrarny vyuzivaji mechanicke energie vody a to predevsim tlakovych a slapovych sil (prilivove a pribojove elektrarny) a tekouci vody v rekach nebo umele vybudovanych vypustich prehrad. Vzdy se ale na energii prevadi pohyb a to bud koly pricnymi a nebo podelnymi s hornim (pro slabsi toky, polohova energie) nebo dolnim (kineticka energie) privodem vody. Ucinnosti se pohybuji v rozsahu 20 % az 65 % pro lopatkova kola, a dokonce 60 % az 80 % pro kola koreckova (s miskami).
[En] Humans have used water energy long time before electricity (water, saw, or iron mills, specific cases, etc.). We can use three types of water energy – chemical (approx. 27 million tons of solid state materials are melted by water per year but this energy is too low for efficient extraction), intrinsic (water layer temperature gradients can be about 20°C, but these power–plants are more thermal plants than water) and mechanical (the water cycle in nature is mainly powered by Sun).
Real water power–plants use mechanical energy – pressure and tidal forces mainly and running water of the rivers or potential energy stored in dams. Energy is converted to the motion in all cases and is used by transverse or longitudinal water wheels with upper (smaller rivers, potential energy) or lower (kinetic energy) drive. Efficiencies are between 20 % and 65 % for paddle wheels and between 60 % and 80 % for bowl wheels.
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[Cz] Prvni zpravy o vodnich kolech pochazi z Ciny a Indie kde se pouzivala jiz pred tisiciletimi pro zavlazovani a snad i ve mlynech. Zbytky mlynu z obdobi 600 let pred nasim letopoctem v podobe, ve ktere se pouzivaji dodnes lze najit napriklad na blizkem vychode, Male Asii nebo na Balkane. V Cechach vznikl prvni mlyn udajne roku 718 na Ohri, jak udava Hajek z Libocan ve sve kronice. Prvni dochovany zaznam se ovsem tyka az mlyna v Uneticich z roku 1125, i kdyz v te dobe zde jiz byly stovky mlynu (napriklad v Pribrami bylo 18 mlynu s celkem 40ti koly). Vodni pohon se ale neuzival pouze ve mlynech, ale temer vsude v kazdodennim zivote. Voda se napriklad pouzivala dokonce k pohonu varecky na michani povidel. O rozmachu mlynu u nas se stale muzeme presvedcit v rade skanzenu, at uz na nekolika mistech na Vysocine, nebo v Roznove pod Radhostem, kde je cela jedna cast skanzenu venovana prave vodni energii.
Krome vodnich kol a pistovych vodnich motoru nesmime opomenout ani vodni trkac objeveny J. Montgolfierem v roce 1797, ktery vyuziva tlakovou energii vody pro cerpani vody samotne do vysokych vysek, detailni popis napr. v [2]. Ale zpet k elektrarnam. K samotnemu pohonu generatoru se pouziva nejcasteji tri druhu turbin. Prvni, Francisova, vytvorena roku 1850 se hodi i na male ale predevsim na velke spady vody. Roku 1884 byla patentovana Peltonova turbina, ktera nepouziva rozvadeci kolo, ale vodu na lopatky privadi vodni trysky. Tato turbina se hodi pro velke spady s malymi prutoky. Nevyhodou Francisovych turbin byly nizke otacky a proto byla V. Kaplanem upravena na turbinu s vrtulovym obeznym kolem, kde byly pouzity nastavitelne rozvadeci lopatky. Krome techto tri zakladnich turbin existuje mnoho jejich modifikaci, ktere zlepsuji vlastnosti dane turbiny pro predem urceny spad vody. Navic existuji i turbiny pro reverzibilni pohon, tzn. ze pokud se roztoci, daji se pouzit i jako cerpadla. Vsechny vodni turbiny maji extremne vysoke ucinnosti az do 95 % a pritom zustavaji ekologicky „ciste“.
[En] The first mention of water wheel is from China and India thousands years ago. Ruins of the mill (600 B.C.) was found in Near East, Asia Minor and Balkans. The first Bohemia water mill were created in 718 A.D. on the Ohre River (recorded in chronicle of Hajek z Libocan). The first real written record is from Unetice in 1125 but we know about hundreds of water mills already created in the Bohemia in this time. Water power was not used in the mills only (e.g. it was used for spoon actuation for plum jam mixing). We can see wide mill history in the Czech outdoor museums in the Roznov pod Radhostem or Vesely kopec in highlands.
In connection to electrical generators we can talk about three types of turbines – Francis’s turbine (1850, greater water falls), Pelton’s turbine (1884, turbine with water jets, big water falls with small flow capacity) and Kaplan’s turbine (enhanced Pelton’s turbine – greater rotation speed). We have a lot of modifications of these three turbines (with enhanced characteristics, irreversible motion, etc.) but efficiency is still high (up to 95 %) and ecologically clear.
[Cz] Opomeneme-li pouhou vyrobu elektriny, plni vodni dila, ktera jsou soucasti elektraren radu dalsich, nemene dulezitych ukolu. Brani zaplavam, davaji nam vodu i v dlouhych obdobich sucha a funguji jako vodni zdroje pro mnoho dalsich odvetvi, napriklad pro jaderne elektrarny, chemicky prumysl apod. To vse dle meho nazoru vyvazuje fakt, ze behem jejich stavby vzdy dojde k zaplaveni velke casti udoli, casto i lidskych sidel, ale na druhou stranu vznikne brzy po ztrate jednoho ekosystemu ekosystem novy, ve kterem hraje voda nemalou ulohu.
[En] Water dams used as water reservoirs for the water power–plants have more than one usage (protect against deluges, keep water in the dry seasons, are used as boilers for factories or other powerplants, etc.). This benefits balances the fact that during their construction will always swamped large parts of the valley, and often human settlements in my opinion. On the other side: after the loss of one ecosystem the new one in which water plays a considerable role is established soon.
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[Cz] Kes je umistena v okoli dvou vodnich elektraren, ktere spolu vzajemne tvori jeden celek. Jednak jde o mensi dolni nadrz Mohelno (17 mil. m³ vody, Kaplanova turbina, vykon 1,2 MW) a vetsi horni prehradu Dalesice (127 mil. m³ vody, 4 Francisovy turbiny, vykon 480 MW). Dohromady funguji obe prehrady jako precerpavaci vodni elektrarna Dalesice, kdy v dobe dostatku elektricke energie se tato energie uskladni v podobe vody v horni nadrzi a naopak v dobe kdy se zvedne odber ze site se voda spusti do dolni prehrady a elektrinu vyrabi. Na stejnem principu pracuje napriklad i znama elektrarna Dlouhe strane. Krome toho ze se jedna o nepostradatelny zdroj vody pro JE Dukovany, jsou obe prehrady zakladnim kamenem rozvodne soustavy CR. Pokud by doslo k vypadku elektriny v cele siti, najede bateriemi zasobena elektrarna Mohelno, ta zacne napajet elektrarnu Dalesice a z ni lze jiz ziskat dostatecny vykon pro obsluhu jaderne elektrarny Dukovany. Jedna se o nejrychlejsi elektrarny v CR, kdy zvladnou Dalesice najet z nuly na plny vykon za 60 s. Ostatne vseobecne vsechny vodni elektrarny jsou pohotovymi a nejrychlejsimi existujicimi elektrarnami.
Budete-li mit cas, urcite se zajdete podivat do informacniho centra v hrazi Dalesicke prehrady, kde se o vodnich elektrarnach dozvite mnohem vice zajimavych informaci. Zaroven muzete odlovit i dalsi kese nachazejici se v blizkosti hrazi obou prehrad.
[En] Cache is located near by two water power–plants which are interconnected to the one pumped storage power–plant. The smaller one – Mohelno (17 mil. m³, one Kaplan’s turbine, 1.2 MW) is used as primary power source for greater one – Dalesice (127 mil. m³, four Francis‘s turbines, 480 MW). These dams are used for water supplying boiler for Nuclear Power–plant Dukovany too. These power–plants (as well as other water–plants) are the fastest power–plants in the world (100 % power can be achieved after 60 s).
If you will have time you can visit info center in the Dalesice dam where you can learn more about water power–plants and visit a lot of geocaches nearby.
[Cz] Kes je soucasti planovane mystery kese „Elektrarenska“. Tato mystery kes neni doposud v provozu, ale bonusove cislo pro budouci kes plati, takze si jej opiste, mate‑li zajem.
[En] The Cache is part of Mystery Cache „Elektrarenska“ which is recently planned. Today it’s not in service but the Bonus Number for it holds so keep it in your notes if you are interested.
[Cz] P.S. Timto bych chtel podekovat geocacherovi Jalav2 za pomoc s vytvarenim teto kese.
[En] Special thanks to the geocacher Jalav2 which helped with creating of this Cache.
Pouzite zdroje / References:
[1] Velka kniha o energii, Plzen 2001, ISBN 80-238-6578-1
[2] http://mve.energetika.cz/jineturbiny/trkac.htm
[3] http://www.cez.cz/cs/vyroba-elektriny/obnovitelne-zdroje/voda/mohelno.html
[4] http://www.cez.cz/cs/vyroba-elektriny/obnovitelne-zdroje/voda/dalesice.html
[5] http://www.cez.cz/cs/kontakty/informacni-centra.html