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Solar-Powered Desalination Plants

- Contributing to the protection of the endangered Arabian Oryx -

[Image]  Hitachi's Solar Powered Desalination plants support the preservation of ecosystems by providing a fresh water supply in desert regions.

At the Hitachi Group, the preservation of ecosystems is a major pillar in our efforts to achieve a sustainable society. We believe that supplying fresh water, which is essential to all life, and caring for the environment in which it is found is a crucial element in this undertaking.
One example is the creation of watering holes in arid deserts, making survival easier for animals who live there. The Hitachi Group is providing the project to protect the endangered Arabian Oryx with a solar-powered desalination plant.

The Endangered Arabian Oryx

[Image]  Extinct in the wild

Have you ever heard of the Arabian Oryx? It is a member of the Bovidae family who inhabit the desert region extending across the Arabian Peninsula. With their characteristic horns that grow long and straight, they are said to have been an archetype for the mythological unicorn.

[Image] Arabian Oryx

Herds of Arabian Oryx once abounded across the Arabian Peninsula, but they were hunted in excessive numbers by people who coveted their beautiful horns. As a result, the animal was extinct in the wild by the late 1960s.

[Image]  Map of the Arabian Peninsula

That is why in the early 1960s the United Arab Emirates (UAE) took several Arabian Oryx from the last remaining heard on the Arabian Peninsula and placed them in zoos and other locations where they could be protected. They were then able to successfully breed the animals in captivity, thereby averting their total extinction. Estimates claim there are now some 5,000 to 7,000 Arabian Oryxes in a protected region of the Arabian Peninsula, and the International Union for Conservation of Nature (IUCN) still designates them as an endangered species.(*)

  • * the species of Arabian Oryx was qualified for a move from Endangered to Vulnerable according to the latest update of the IUCN Red List of Threatened Species™ released on June 16 in 2011.

Project to Protect Desert Animals

[Image]  Drinking water in the desert

In the Emirate of Abu Dhabi, one of the United Arab Emirates, a project led by the Crown Prince is now underway to protect rare desert animals, including the endangered Arabian Oryx.

The project is using Hitachi group's proprietary solar-powered desalination technology, which uses energy from the sun to supply fresh drinking water.

[Image]  Diagram of solar-powered desalination plant

Vast deserts are a difficult environment in which to secure a stable water supply — something that is essential to all life. The ground water that lies under deserts has a high salt content, and it was once believed such water was unsuitable for drinking.
Hitachi's solar-powered desalination plant, however, uses a special desalination unit to produce drinking water by removing the high salt content found in the desert ground water. After excessive salt is removed from the water by the desalination unit, it is sent to a waterway through pipes laid under the sand, feeding waterholes that give the Arabian Oryx and other desert animals access to life-sustaining drinking water.

[Image]  Energy from the Sun

Securing a source of power in desert regions is another major issue. There is no electricity in the remote desert expanse where these animals live. However, there is no lack of sunlight daily beaming down. That is why solar panels are installed to harness this energy and produce electricity from the power of the sun.

[Image]  Solar panels

Harnessing the abundant energy of the sun makes it possible to supply the power needed to run the desalination plant. Thereby providing a stable source of drinking water to the Arabian Oryx and other desert animals in an environmentally conscious manner.

Desalination System Design

[Image]  Desalination system

The desalination unit employs a special filter known as an RO membrane.* RO membranes have 0.0001 micron pores that allow only water molecules to pass through. Water is thereby desalinated by the retention of salts and impurities.
This filtering technology is known as reverse osmosis (RO).

  • * RO membranes: RO is an acronym for reverse osmosis, a process in which pressure is applied to force water containing salt and other impurities across a membrane to purify it at a molecular level. The reverse osmosis of water using RO membrane results in clean drinkable water.

Let's take a look at the principle behind reverse osmosis. We will start with an explanation of the mechanism of normal osmosis.
When saltwater and freshwater are separated by a semi-permeable membrane*, freshwater will naturally move to the saltwater side until the salt content of both sides has equalized. This phenomenon is known as osmosis, and the movement continues until a specific pressure differential, known as osmotic pressure, results.
Reverse osmosis, as the name implies, moves in the opposite direction of natural osmosis. External pressure at or above osmotic pressure is applied to water containing impurities, such as salts. This results is water molecules being forced to pass through the membrane in the opposite direction of normal osmosis. That is the phenomenon known as reverse osmosis.

[Image]  Mechanism of osmosis and reverse osmosis

  • * Semi-permeable membrane: A membrane that only allows through molecules of a certain size or smaller. The cell membranes of plants and animals are semi-permeable membranes, they let water molecules pass through while keeping out salts.

Desalination units like this help to sustain adequate supplies of drinking water not only in Japan but in other parts of the world which are facing severe water-related problems. This technology and know how is also helping to protect endangered species.

The Hitachi Group — Supporting Ecosystem Preservation through Water Projects

Hitachi use desalination units to produce drinking water from groundwater with a high salt content. The power required to do this is provided by solar energy. Building a water supply system that integrates this unique solar power generation and desalination plant requires advanced technology and know how.

[Image]  Reliable operation via natural energy

Natural energy sources, such as sunlight, are unreliable as they are easily affected by weather conditions. That is why when clouds reduce the amount of power being generated, Hitachi's solar-powered desalination plant can run on batteries that have stored excess solar energy. Operating the desalination plant in such a reliable manner makes it possible to utilize energy more effectively than if it had to be turned on and off at frequent intervals.

But if battery power falls below a certain level, there is also a mechanism that automatically halts the power supply from them. This design, which ensures that the batteries are never completely drained, prevents disruptions to the control system and other systems required for a minimum level of plant operation.
Furthermore, not only do workers visit the site once per day to check on its operational status, they also remotely monitor the system 24 hours a day using GPRS* technology.

  • * GPRS: General packet radio service
    Data transmission technology that uses cellular phone networks. It is one of the technologies known as 2.5 generation (2.5G) which can send/receive data in packets.

[Image] Flexible designs according to environment and use

In addition to solar power, Hitachi can also provide desalination plants which employ wind power. Their rate of adoption is expected to grow as they employ natural energy in the local environment, making them suitable for locations where it is difficult to secure conventional power supplies.

Furthermore, the Hitachi Group can design plants which are tailored to specific environments, purposes, uses, and scales among other things. The Hitachi Group is internationally recognised as a preeminent provider of optimal water environmental solutions by customizing its world-class water treatment technology. This includes water source preservation, above and below ground water supplies, flood control/irrigation, and wastewater reuse, according to local needs.

This is the policy of the Hitachi Group, and we will help preserve ecosystems by globally expanding water projects that support life.

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