Okinawa Yanbaru Seawater Pumped Storage Power Station

{{Short description|Experimental hydroelectric power station in Okinawa Prefecture, Japan}}

{{Infobox dam

| name =

| name_official =

| image = Seawater intake-outlet of Yanbaru Power Station.jpg

| image_caption = The seawater intake/outlet faced the Pacific Ocean, which served as the lower reservoir for this power station. The upper reservoir is not shown in this picture.

| coordinates = {{coord|26|40|25|N|128|15|56|E|type:landmark|display=inline,title}}

| country = Japan

| location = Kunigami, Okinawa

| status = Dismantled

| construction_began =

| opening = May 16, 1999

| demolished = 2016

| cost =

| owner =

| operator = Electric Power Development Company

| res_name =

| res_capacity_total = {{convert|564000|m3|acre.ft|abbr=on}}

| lower_res_name = Pacific Ocean

| plant_pumpgenerators =

| plant_turbines =

| plant_pumps =

| plant_hydraulic_head =

| plant_capacity = {{convert|30|MW|abbr=on}}

| plant_capacity_factor =

| website =

}}

The {{nihongo|Okinawa Yanbaru Seawater Pumped Storage Power Station|沖縄やんばる海水揚水発電所|Okinawa Yanbaru Kaisui Yōsui Hatsudensho}} was an experimental hydroelectric power station located in Kunigami, Okinawa, Japan and operated by the Electric Power Development Company. It was the world’s first pumped-storage facility to use seawater for storing energy. Its maximum output was 30 MW. Construction of the plant started in 1987 and was completed in 1999 {{Cite web|url=https://www.waterpowermagazine.com/features/featurejapanese-pumped-storage-embraces-the-ocean-waves/|title=Japanese pumped storage embraces the ocean waves - International Water Power|website=www.waterpowermagazine.com|access-date=2019-10-06}} at a cost of ¥3.2 billion. It was dismantled in 2016.

Facility

The power station was a pure pumped-storage facility, using the Pacific Ocean as its lower reservoir, with an effective drop of 136 m and maximum flow of 26 m³/s. Its pipelines and pump turbine were installed underground. Its maximum output was approximately 2.1% of the maximum power demand in the Okinawa Island recorded on August 3, 2009.

The upper reservoir, artificially excavated, was approximately {{convert|600|m}} away from the shoreline and approximately {{convert|150|m}} above sea level. It had an octagonal planar shape with a maximum width of {{convert|252|m}}. Its maximum depth was {{convert|25|m}} and its effective storage capacity was {{convert|564000|m3|acre.ft}}. The entire inner surface of the reservoir was covered with an impermeable liner to prevent seawater from leaking and damaging the surrounding vegetation.

Fiber-reinforced plastic tubes were adopted for the penstock and the tailrace instead of steel tubes in order to avoid seawater corrosion and adhesion of barnacles. The pump turbine was partially made of stainless steel resistant to seawater.

A 66 kV line connected the power station with the power grid of The Okinawa Electric Power Company.

History

The power station was a pilot plant funded by the Agency for Natural Resources and Energy and constructed by the Electric Power Development Company. A five-year verification operation was conducted beginning on May 16, 1999. The Japan Society of Civil Engineers presented the company an Outstanding Civil Engineering Achievement Award on May 26, 2000 for its construction of the plant.

The operator could not put the power station into practical use because the demand for electric power in Okinawa had not grown as predicted, and the plant was not profitable as a business. The power plant was dismantled in July 2016.

References

{{reflist|33em|refs =

{{cite journal

| last1 = Shibuya

| first1 = Yōko

| last2 = Ishimura

| first2 = Yōsuke

|date=March 2010

| script-title=ja:学生が行く今月の土木日本一: 世界初の海水揚水発電所: 沖縄やんばる海水揚水発電所

|trans-title=This month’s civil engineering number one in Japan visited by students: World’s first seawater pumped-storage power station: Okinawa Yanbaru Seawater Pumped Storage Power Station

| journal = JSCE Magazine

| volume = 95

| issue = 3

| pages = 34–35

| language = Japanese

| issn = 0021-468X

| url = http://www.jsce.or.jp/journal/student/nihonichi/201003.pdf

}}

{{cite journal

| last1 = Ōmoto

| first1 = Kazuhiro

|date=October 1994

| script-title=ja:現場を訪ねて: 沖縄海水揚水建設所: 自然にやさしく

|trans-title=Visiting construction site: Okinawa Yanbaru Seawater Pumped Storage Power Station: Nature-friendly

| journal = Soil Mechanics and Foundation Engineering

| volume = 42

| issue = 10

| pages = 47–50

| language = Japanese

| issn = 0041-3798

| url = http://ci.nii.ac.jp/naid/110003972821

}}

{{cite journal

|last1 = Fujihara

|first1 = Tetsuo

|last2 = Imano

|first2 = Haruo

|last3 = Oshima

|first3 = Katsuhiro

|date = October 1998

|title = Development of pump turbine for seawater pumped-storage power plant

|journal = Hitachi Review

|volume = 47

|issue = 5

|pages = 199–202

|issn = 0018-277X

|url = http://www.hitachi.com/rev/1998/revoct98/r4_108.pdf

|access-date = 2010-12-30

|archive-date = 2013-04-26

|archive-url = https://web.archive.org/web/20130426230652/http://www.hitachi.com/rev/1998/revoct98/r4_108.pdf

|url-status = dead

}}

{{cite web

| url = http://www.jpower.co.jp/news_release/news092.html

| script-title=ja:沖縄やんばる海水揚水発電所の実証試験運転開始について

| date = 17 March 1999

| work = News Release

| publisher = Electric Power Development Company

| language = Japanese

|trans-title=Verification operation started at Okinawa Yanbaru Seawater Pumped Storage Power Station

}}

{{cite web

| url = http://www.jpower.co.jp/news_release/news125.html

| script-title=ja:「沖縄やんばる海水揚水発電所の建設」の土木学会技術賞の受賞について

| date = 26 May 2000

| work = News Release

| publisher = Electric Power Development Company

| language = Japanese

|trans-title=JSCE Outstanding Civil Engineering Achievement Award for construction of Okinawa Yanbaru Seawater Pumped Storage Power Station

}}

{{cite web

| url = http://www.okiden.co.jp/shared/pdf/news_release/2009/090804_02.pdf

| script-title=ja:最大電力の記録を更新 (今年2回目)

| date = 4 August 2009

| work = Press Release

| publisher = Okinawa Electric Power Company

| language = Japanese

|trans-title=Maximum power demand again hits record high

}}

{{cite journal

|date=29 July 2016

| title = Experimental power plant in Kunigami dismantled

| journal = Japanupdate

| url = http://www.japanupdate.com/2016/07/experimental-power-plant-in-kunigami-dismantled/

}}

External links

[https://web.archive.org/web/20111002083405/http://www.jpower.co.jp/yambaru/ Okinawa Yanbaru Seawater Pumped Storage Power Station] (Official site, in Japanese)
{{cite web

|url = http://www.jcold.or.jp/Eng/Seawater/Seawater.htm

|work = Japan Commission on Large Dams

|title = Seawater Pumped-Storage Power Plant

|archiveurl = https://web.archive.org/web/20020708041342/http://www.jcold.or.jp/Eng/Seawater/Seawater.htm

|archivedate = 2002-07-08

|url-status = dead

}}