Submarine power cable

# Submarine power cable

Discussion
 Ask a question about 'Submarine power cable' Start a new discussion about 'Submarine power cable' Answer questions from other users Full Discussion Forum

Encyclopedia
Submarine power cables are major transmission cables for carrying electric power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

below the surface of the water. These are called "submarine" because they usually carry electric power beneath salt water
Seawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...

(arms of the ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

, sea
Sea
A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...

s, strait
Strait
A strait or straits is a narrow, typically navigable channel of water that connects two larger, navigable bodies of water. It most commonly refers to a channel of water that lies between two land masses, but it may also refer to a navigable channel through a body of water that is otherwise not...

s, etc.) but it is also possible to use submarine power cables beneath fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...

(large lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

s and river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

s). Examples of the latter exist that connect the mainland with large islands in the St. Lawrence River.

## Design technologies

Most power systems use alternating-current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

. This is due mostly to the simplicity of the AC transformer, which allows AC voltages to be easily stepped up and down. When the voltage is stepped up, current through the line is reduced, and since resistive losses in the line are proportional to the square of the current, stepping up the voltage significantly reduces the resistive line losses. The lack of a simple DC transformer made DC systems impractical in the late 19th and early 20th centuries. As technology improved, DC transformers became possible, though even today they are much more complex than AC transformers. A DC transformer often consists of an oscillator or inverter to convert the DC to AC, an AC transformer to do the actual voltage stepping, and then a rectifier and filter stage to convert the AC back to DC.

DC switch gear is also more expensive to produce, since arc suppression
Arc suppression
Arc suppression is a method of attempting to reduce to near elimination the luminous discharge of electrical current , between two electrodes, through a gas...

is more difficult. When a high voltage AC line is switched off, the voltage will arc across the switch contacts. Once the contacts get far enough apart, the arc will naturally extinguish itself since the voltage drops to zero twice during the AC sine wave cycle. Since DC is constant and doesn't cycle to zero, a DC switch will draw a much longer arc, and suppressing this arc requires more expensive switching equipment.

DC power transmission does have some advantages over AC power transmission. AC transmission lines need to be designed to handle the peak voltage of the AC sine wave. However, since AC is a sine wave, the effective power that can be transmitted through the line is related to the root mean squared (RMS) value of the voltage, which for a sine wave is only 0.7 times the peak value. This means that for the same size wire and same insulation on standoffs and other equipment, a DC line can carry 1.4 times as much power as an AC line.

AC power transmission also suffers from reactive losses, due to the natural capacitance and inductive properties of wire. DC transmission lines do not suffer reactive losses. The only losses in a DC transmission line are the resistive losses, which are present in AC lines as well.

For an overall power transmission system, this means that for a given amount of power, AC requires more expensive wire, insulators, and towers but less expensive equipment like transformers and switch gear on either end of the line. For shorter distances, the cost of the equipment outweighs the savings in the cost of the transmission line. Over longer distances, the cost differential in the line starts to become more significant, which makes high-voltage direct current
High-voltage direct current
A high-voltage, direct current electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses...

For underwater transmission systems, the line losses due to capacitance are much greater, which makes HVDC economically advantageous at a much shorter distance than on land.

### Alternating current cables

Alternating-current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

(AC) submarine cable systems for transmitting lower amounts of three phase electric power can be constructed with three-core cables in which all three insulated conductors are placed into a single underwater cable. Most offshore-to-shore wind-farm cables are constructed this way.

For larger amounts of transmitted power, the AC systems are composed of three separate single-core underwater cables, each containing just one insulated conductor and carrying one phase of the three-phase electric current
Three-phase electric power
Three-phase electric power is a common method of alternating-current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by grids worldwide to transfer power. It is also used to power large motors and other heavy loads...

. A fourth identical cable is often added in parallel with the other three, simply as a spare in case one of the three primary cables is damaged and needs to be replaced. This damage can happen, for example, from a ship's anchor
Anchor
An anchor is a device, normally made of metal, that is used to connect a vessel to the bed of a body of water to prevent the vessel from drifting due to wind or current. The word derives from Latin ancora, which itself comes from the Greek ἄγκυρα .Anchors can either be temporary or permanent...

carelessly dropped onto it. The fourth cable can substitute for any one of the other three, given the proper (and complicated) electrical switching system.
• Mainland British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

to Nelson Island
Nelson Island (British Columbia)
Nelson Island is an island in the Sunshine Coast region of the South Coast region of British Columbia. It is surrounded by Hotham Sound, Agamemnon Channel, and Malaspina Strait. The closest communities are Pender Harbour, British Columbia and Egmont, both on the Sechelt Peninsula.The island is...

Texada Island is the largest island in the Strait of Georgia of British Columbia, Canada. Its northern tip is located about southwest of the city of Powell River and west of the Sechelt Peninsula on the Sunshine Coast. A former mining and logging area, the island still has a few quarries and old...

to Vancouver Island
Vancouver Island
Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...

, the destination of the power. This is a high-capacity 500 kilovolt (kV) three-phase system.
• Mainland Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

to Bornholm Island, Denmark
Bornholm
Bornholm is a Danish island in the Baltic Sea located to the east of the rest of Denmark, the south of Sweden, and the north of Poland. The main industries on the island include fishing, arts and crafts like glass making and pottery using locally worked clay, and dairy farming. Tourism is...

, Bornholm Cable
Bornholm Cable
Bornholm Cable is one of the longest submarine three phase AC cable in the world. It is a 60 kV cable interconnecting the power grids of Bornholm and Sweden....

( 60 kilovolts).
• Under the Strait of Messina
Strait of Messina
The Strait of Messina is the narrow passage between the eastern tip of Sicily and the southern tip of Calabria in the south of Italy. It connects the Tyrrhenian Sea with the Ionian Sea, within the central Mediterranean...

, connecting southern tip of the mainland of Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

with the large island of Sicily
Sicily
Sicily is a region of Italy, and is the largest island in the Mediterranean Sea. Along with the surrounding minor islands, it constitutes an autonomous region of Italy, the Regione Autonoma Siciliana Sicily has a rich and unique culture, especially with regard to the arts, music, literature,...

(380 kV). This submarine cable replaced an earlier, and very long overhead line crossing
An overhead line crossing is the crossing of an obstacle—such as a traffic route, a river, a valley or a strait—by an overhead power line. The style of crossing depends on the local conditions and regulations at the time the power line is constructed. Overhead line crossings can...

(the "Pylons of Messina
Pylons of Messina
The Pylons of Messina were once used to carry a 220 kilovolt powerline across the Strait of Messina, between the Rizziconi substation in Calabria on the Italian mainland and the Sorgente substation in Sicily.-Design:...

")
• Negros Island to Panay Island
Panay Island
Panay is an island in the Philippines located in the western part of the Visayas. Politically, it is divided into five provinces: Aklan, Antique, Capiz, and Iloilo, all in the Western Visayas Region. It is located southeast of the island of Mindoro and northwest of Negros, separated by the...

, in the Philippines (138 kV)

### Direct current cables

• Baltic-Cable - between Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

and Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

beneath the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

Basslink is a high-voltage direct current cable link crossing Bass Strait, connecting the Loy Yang Power Station, Victoria on the Australian mainland to the George Town substation in northern Tasmania...

- between the mainland State of Victoria and the island of Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, 500 kilovolts (kV), with a length of 290 kilometers beneath the Bass Strait
Bass Strait
Bass Strait is a sea strait separating Tasmania from the south of the Australian mainland, specifically the state of Victoria.-Extent:The International Hydrographic Organization defines the limits of the Bass Strait as follows:...

• BritNed
BritNed
BritNed is a high-voltage direct-current submarine power cable between the Isle of Grain in Kent, the United Kingdom, and Maasvlakte in Rotterdam, the Netherlands.-History:...

- between the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

and Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

beneath the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

• Cross Sound Cable
Cross Sound Cable
The Cross Sound Cable is a long bipolar high-voltage direct current submarine power cable between New Haven, Connecticut, USA and Shoreham, Long Island New York , USA. The Cross Sound Cable can transmit a maximum power of 330 MW at a voltage of +/- 150 kV DC. The maximum current for Cross Sound...

- between Long Island, New York, and the State of Connecticut beneath Long Island Sound
Long Island Sound
Long Island Sound is an estuary of the Atlantic Ocean, located in the United States between Connecticut to the north and Long Island, New York to the south. The mouth of the Connecticut River at Old Saybrook, Connecticut, empties into the sound. On its western end the sound is bounded by the Bronx...

Estlink is a set of HVDC submarine cables between Estonia and Finland. Estlink 1 is the first interconnection between the Baltic and Nordic electricity markets following by Estlink 2 in 2014...

- between northern Estonia
Estonia
Estonia , officially the Republic of Estonia , is a state in the Baltic region of Northern Europe. It is bordered to the north by the Gulf of Finland, to the west by the Baltic Sea, to the south by Latvia , and to the east by Lake Peipsi and the Russian Federation . Across the Baltic Sea lies...

and southern Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

beneath the Gulf of Finland
Gulf of Finland
The Gulf of Finland is the easternmost arm of the Baltic Sea. It extends between Finland and Estonia all the way to Saint Petersburg in Russia, where the river Neva drains into it. Other major cities around the gulf include Helsinki and Tallinn...

• Fenno-Skan
Fenno-Skan
Fenno–Skan is the designation of the high voltage direct current transmission between Dannebo in Sweden and Rauma in Finland.-History:Fenno–Skan was inaugurated in 1989. Taken into commercial operation in November 1989, Fenno–Skan was the longest submarine power cable in the world...

- between Sweden and Finland beneath the Baltic Sea
• HVDC Cross-Channel
HVDC Cross-Channel
The HVDC Cross-Channel is the high voltage direct current connection that operates under the English Channel between the continental European and British electricity grids.-1961 cable:...

- very high power cable between the French mainland
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

and the island of Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

beneath the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

• HVDC Gotland
HVDC Gotland
The HVDC Gotland, on the Swedish east coast, was the first fully commercial static plant for high voltage direct current transmission in the world. The first HVDC Gotland link went into service in 1954. It could transfer 20 megawatts over a 98-kilometer-long submarine cable between Västervik on...

- the first HVDC submarine power cable (non-experimental) - between the Swedish mainland
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

and the Swedish island of Gotland
Gotland
Gotland is a county, province, municipality and diocese of Sweden; it is Sweden's largest island and the largest island in the Baltic Sea. At 3,140 square kilometers in area, the region makes up less than one percent of Sweden's total land area...

beneath the Baltic Sea
• HVDC Inter-Island
HVDC Inter-Island
The HVDC Inter-Island link is a high-capacity, bipolar high-voltage direct current transmission system connecting the electricity transmission networks of New Zealand's two main islands to form the National Grid. The HVDC link is owned and operated by state-owned transmission company Transpower...

- between the power-rich South Island
South Island
The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

(much hydroelectric power) of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

and the more-populous North Island
North Island
The North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...

beneath the Cook Strait
Cook Strait
Cook Strait is the strait between the North and South Islands of New Zealand. It connects the Tasman Sea on the west with the South Pacific Ocean on the east....

• HVDC Italy-Corsica-Sardinia
HVDC Italy-Corsica-Sardinia
The HVDC Italy–Corsica–Sardinia is used for the exchange of electric energy between the static inverter plant Suvereto on the Italian mainland, the static inverter plant Lucciana on Corsica and the static inverter plant Codrongianos on Sardinia.First used in 1965 as mono-polar line, today this...

(SACOI) - between the Italian mainland
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, the Italian island of Sardinia
Sardinia
Sardinia is the second-largest island in the Mediterranean Sea . It is an autonomous region of Italy, and the nearest land masses are the French island of Corsica, the Italian Peninsula, Sicily, Tunisia and the Spanish Balearic Islands.The name Sardinia is from the pre-Roman noun *sard[],...

, and its neighboring French island of Corsica
Corsica
Corsica is an island in the Mediterranean Sea. It is located west of Italy, southeast of the French mainland, and north of the island of Sardinia....

beneath the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

• HVDC Italy-Greece
HVDC Italy-Greece
The HVDC Italy–Greece is a monopolar submarine power cable link between Italy and Greece with a maximum transmission power of 500 megawatts. It went in service in 2001. The HVDC Italy-Greece begins in the static inverter plant Galatina situated at in Italy and is implemented in its first as...

- between Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

and Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

The Adriatic Sea is a body of water separating the Italian Peninsula from the Balkan peninsula, and the system of the Apennine Mountains from that of the Dinaric Alps and adjacent ranges...

• HVDC Leyte - Luzon
HVDC Leyte - Luzon
The HVDC Leyte–Luzon is a high voltage direct current transmission link in the Philippines between geothermal power plants on the island of Leyte and the southern part of island of Luzon. The HVDC Leyte – Luzon went in service on 10 August 1998....

- between Leyte Island
Leyte Island
Leyte is an island in the Visayas group of the Philippines.The island measures about 180 km north-south and about 65 km at its widest point. In the north it nearly joins Samar, separated by the San Juanico Strait, which becomes as narrow as 2 km in some places...

and Luzon
Luzon
Luzon is the largest island in the Philippines. It is located in the northernmost region of the archipelago, and is also the name for one of the three primary island groups in the country centered on the Island of Luzon...

in the Philippines, beneath the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

• HVDC Moyle
HVDC Moyle
The HVDC Moyle is the HVDC link between Auchencrosh, South Ayrshire in Scotland and Ballycronan More, County Antrim in Northern Ireland, which went into service in 2001. It is owned and operated by Mutual Energy....

- connecting Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

with Northern Ireland
Northern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...

within the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, and thence to the Republic of Ireland
Republic of Ireland
Ireland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...

, beneath the Irish Sea
Irish Sea
The Irish Sea separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man...

• HVDC Vancouver Island
HVDC Vancouver Island
The HVDC Vancouver Island is the name for HVDC interconnection between the Vancouver Island Terminal near North Cowichan, British Columbia on Vancouver Island at and the Arnott Substation near Delta, British Columbia at on the Canadian mainland, which went into operation in 1968 and was...

- between Vancouver Island
Vancouver Island
Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...

and the mainland of the Province of British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, beneath the Strait of Juan de Fuca
Strait of Juan de Fuca
The Strait of Juan de Fuca is a large body of water about long that is the Salish Sea outlet to the Pacific Ocean...

• Kii Channel HVDC system
Kii Channel HVDC system
The Kii Channel HVDC system in Japan is, as of 2010, the highest-capacity high-voltage direct current submarine power cable system in the world...

- now (2010) the world's highest-capacity long-distance submarine power cable (rated at 1400 megawatts). This power cable connects the large islands of Honshu
Honshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...

and Shikoku
Shikoku
is the smallest and least populous of the four main islands of Japan, located south of Honshū and east of the island of Kyūshū. Its ancient names include Iyo-no-futana-shima , Iyo-shima , and Futana-shima...

beneath the Kii Channel
Kii Channel
The is a strait separating the Japanese Home Islands of Honshū and Shikoku. This channel connects the Inland Sea with the Pacific Ocean....

in the Japanese Home Islands
• Kontek
Kontek
The Kontek is a 170 kilometer long, monopolar 400kV DC-cable for the interconnection of the German power grid with the electricity grid of the Danish island Sealand. The name comes from "continent" and the name of the former Danish power transmission company "Elkraft", which operated the power grid...

- between Germany and Denmark beneath the Baltic Sea
• Konti-Skan
Konti-Skan
Konti–Skan is the name of high-voltage direct-current transmission line between Denmark and Sweden.-Technical description:...

- between Sweden and Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

beneath the Baltic Sea
• Neptune Cable
Neptune Cable
The Neptune Cable is a 500kV and 660 MW high-voltage direct current submarine power cable between Sayreville, New Jersey and Levittown, New York on Long Island. It carries 22 percent of Long Island's electricity....

- between the State of New Jersey and Long Island, New York - 64 miles beneath the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

• Skagerrak 1-3, 3 cables between Norway and Denmark (Jutland) - 1000 MW in all
• Swepol
Swepol
SwePol is a -long monopolar high-voltage direct current submarine cable between the Stärnö peninsula near Karlshamn, Sweden, and Bruskowo Wielkie, near Słupsk, Poland....

- between Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

and Sweden beneath the Baltic Sea

### Longest

• NorNed
NorNed
NorNed is a long HVDC submarine power cable between Feda in Norway and the seaport of Eemshaven in the Netherlands, which interconnects both countries' electricity grids. It is the longest submarine power cable in the world. Budgeted at €550 million, and completed at a cost of €600m, the...

(between Eemshaven
Eemshaven
thumb|right|[[Satellite]] [[image]] of the Ems [[estuary]] showing the location of Eemshaven Eemshaven is a seaport in Groningen, Netherlands....

, Netherlands and Feda
Feda
Feda former municipality in Vest-Agder county in Norway. It is located in the present-day municipality of Kvinesdal. In 2009, the village of Feda had a population of 390....

, Norway), HVDC, 700 MW, 580 km (360 mi)http://www05.abb.com/global/scot/scot221.nsf/veritydisplay/f3a6c2afe601d185c125718e002e3823/\$File/THE%20NORNED%20HVDC%20CABLE%20LINK.pdf

## Proposed submarine power cables

• Champlain Hudson Power Express
Champlain Hudson Power Express
The Champlain Hudson Power Express is a high-voltage direct current submarine power cable project linking the Montreal area to the New York City suburb of Yonkers...

, 335-mile line. The Transmission Developers Company of Toronto, Ontario, is proposing "to use the [ Hudson River
Hudson River
The Hudson is a river that flows from north to south through eastern New York. The highest official source is at Lake Tear of the Clouds, on the slopes of Mount Marcy in the Adirondack Mountains. The river itself officially begins in Henderson Lake in Newcomb, New York...

] for the most ambitious underwater transmission project yet. Beginning south of Montreal
Montreal
Montreal is a city in Canada. It is the largest city in the province of Quebec, the second-largest city in Canada and the seventh largest in North America...

, a 335-mile line would run along the bottom of Lake Champlain
Lake Champlain
Lake Champlain is a natural, freshwater lake in North America, located mainly within the borders of the United States but partially situated across the Canada—United States border in the Canadian province of Quebec.The New York portion of the Champlain Valley includes the eastern portions of...

, [and then] down the bed of the Hudson
Hudson River
The Hudson is a river that flows from north to south through eastern New York. The highest official source is at Lake Tear of the Clouds, on the slopes of Mount Marcy in the Adirondack Mountains. The river itself officially begins in Henderson Lake in Newcomb, New York...

all the way to New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

."
• Power Bridge, Hawaii
• Power Bridge, State of Maine
• Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...

to the Virgin Islands
Virgin Islands
The Virgin Islands are the western island group of the Leeward Islands, which are the northern part of the Lesser Antilles, which form the border between the Caribbean Sea and the Atlantic Ocean...

• 400 kV HVDC India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

to Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

• Atlantic Wind Connection
Atlantic Wind Connection
Atlantic Wind Connection is an electrical transmission backbone proposed by Trans-Elect Development Company that could be constructed starting in 2013 off the East Coast of the United States to service off-shore wind farms...

between Delaware
Delaware
Delaware is a U.S. state located on the Atlantic Coast in the Mid-Atlantic region of the United States. It is bordered to the south and west by Maryland, and to the north by Pennsylvania...

and New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

, potentially between Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

and New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

Newfoundland and Labrador is the easternmost province of Canada. Situated in the country's Atlantic region, it incorporates the island of Newfoundland and mainland Labrador with a combined area of . As of April 2011, the province's estimated population is 508,400...

and province of Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...

• 200 megawatts 95 km Magħtab (Malta
Malta
Malta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...

) and Marina the Ragusa (Sicily
Sicily
Sicily is a region of Italy, and is the largest island in the Mediterranean Sea. Along with the surrounding minor islands, it constitutes an autonomous region of Italy, the Regione Autonoma Siciliana Sicily has a rich and unique culture, especially with regard to the arts, music, literature,...

)
• The 58.9-km, 161-kV Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

PengHu submarine power cable system (T-P-Cable), the first submarine project of the Taiwan Power Company
Taiwan Power Company
The Taiwan Power Company is a state-owned electric power utility providing electric power to Taiwan and off-shore islands of Republic of China. In 1994 a measure which allowed independent power producers to provide up to 20 percent of Taiwan's electricity should have ended the monopoly.- See...

(Taipower) in this level, will be commercially operated in 2012.
• Skagerrak 4, addition to the 3 DC cables between Norway and Denmark, 700 MW, 140 km, ready 2014