Secret Japanese solar power station looks like "round petals" (Figure)

Yokohama "metal petal" solar energy complex is the future direction of electric power development

According to foreign media reports, there are many petal-like metal devices in Yokohama, Japan, but they are not artistic sculptures but are new types of integrated solar power facilities. After Japan experienced an acute shortage of electricity after the earthquake and tsunami on March 11, 2011, this state-of-the-art solar power station will be an important part of Yokohama's power system. In addition, due to the serious nuclear accident after the earthquake at the Fukushima nuclear power plant, it triggered the world's discussion on the safety of nuclear power. Japan has a huge number of nuclear power units, forcing it to re-evaluate the new energy strategy.

According to statistics, of the 54 civilian nuclear reactors in Japan, 52 of them have been maintained after the Fukushima nuclear power plant incident. The remaining two will be shut down for repairs this spring. Before Japan’s national and local governments re-evaluated whether nuclear reactors could operate safely, these reactors still could not play their due role, resulting in a 30% power gap. Rising electricity prices have also hindered the investors’ capital cycle. Therefore, a variety of energy supply solutions pioneered by solar energy technology are currently the focus. However, this plan is not implemented by the Japanese government. Instead, it is the Japanese steel engineering holding company JFE Group, one of the five largest steel giants in Tokyo.

For energy-intensive steel production, reliable power supply is the key to the future steel industry. Yokohama is a port city with new solar power plants distributed along the coastline and is expected to achieve 40 to 60 kilowatts of output power this spring. The power station is most notably a neat array of heliostats, which can be adjusted to the angle of the receiving tower based on changes in the angle of the sun, forming a set of photovoltaic power generation systems. Two other types of solar integrated power facilities are also under construction.

Solar power station light collection efficiency

The Yokohama “Metal Petal” solar power station is composed of 87 heliostats that automatically track the sun's operating angle and reflect sunlight to a 20-meter (65-foot) high light energy receiver. High tower solar power equipment (CPV) ) The efficiency is twice that of traditional silicon materials, which benefits from about 800 circular mirror surfaces. The solar cells behind the mirror can also generate electricity directly. When hundreds of “petal” mirrors are working simultaneously, the receiving tower will become extremely hot. For this reason, researchers at the JFE Steel Group have also developed a water circulation cooling system. The circulating water exists in the solar module and the cooling device. And minimize the use of water. Photo courtesy of Japan Steel Engineering Holdings (JFE Group).

Solar Tracking Technology in Space Age

A large number of heliostats make up the concentrated photovoltaic energy system of the Yokohama solar power station. Among them, 80 mirror sets are equipped with tracking sensors to maintain the change of the elevation angle to the sun, and the other 7 mirror sets use the plane right-angled mirror to run according to the program. Circular mirrors were developed by Mitaka Kohki, and other high-precision instruments were developed by NASA and the Japan Institute of Space and Aerospace Science. The solar mirror uses the tracking sensor technology of the space solar observation telescope. Although the mirror surface has been coated with a protective coating, JFE Group, the Japanese steel engineering company, believes that there is a need to develop a device that automatically cleans the mirror surface because the smoothness of the mirror surface directly affects the efficiency of the reflected sunlight, which can increase the collection efficiency. The ability of the sun.

Solar energy conversion principle

The figure shows the acceptance of the tower from the perspective of the solar reflecting mirror on the ground. The concentrating solar power system of the Yokohama Solar Power Plant formally uses this solar orientation reflector to focus the sunlight on a receiving tower that is 20 meters high. However, CSP receivers, solar cells, and concentrating solar thermal generators are used to convert light energy to generate steam. The working principle in the following is similar to that of a thermal power plant. The high-temperature steam generated promotes the turbine. This method of power supply is the same as that of other thermal nuclear power plants. The solar power plant did not install an expensive steam turbine for power generation during the pre-test period.

New type of solar power is suitable for coastal countries with small land area

After the system is fully operational, it will be suitable for large-scale power generation tasks and storage heat to provide support for night-time power generation. Solar photovoltaic cells and concentrating solar thermal generators only support direct sunlight to the mirror surface. Compared to domestic electricity consumption, Japan Steel Engineering Corporation’s JFE Group's technology can also support the power generation needs of various climatic conditions. The company also integrates high- tower solar power generation equipment with solar photovoltaic cells and concentrated solar thermal power generator technology, which is more cost-effective and power-generating, and can generate electricity at night and in rainy weather.

The centralized solar thermal power generation system relies on a concentrator to generate steam at 450 degrees Celsius and about 842 degrees Fahrenheit. The main equipment is a linear collection tube installed 2 meters above the plane mirror. The relatively simple structure means less cost, and the former has the advantage of being free from wind interference compared to conventional parabolic trough mirrors. In 2011, the engineers of the JEF Group were licensed to use the technology of the German Solar Power Development Group and obtained exclusive sales rights in Southeast Asia. Even so, the installed capacity of the system in Japan was limited to a small number of solar power stations, and the JFE Group mainly focused on Sales of solar thermal collectors using linear Fresnel technology.

Although the solar power generation efficiency is higher than that of the conventional photovoltaic power generation system, Japan lacks a large area of ​​land, and the required installation environment should be dry and cloudless weather. Japan conducted nationwide solar power generation tests in the 1970s and 1980s, but failed to obtain breakthrough research results and stopped further research. Another reason is that Japan's domestic solar photovoltaic cells and concentrating solar energy generator technology lack commercial interests. The new policy requires that public government agencies use electricity to purchase electricity from renewable energy, but it does not use solar energy to generate electricity. Inclusion requirements. However, the plan can sign long-term contracts with solar investors and exceed market prices, reflecting the high cost of solar power generation.

Global warming and cutting-edge solar power station construction

Before the construction of a new-type sophisticated solar energy complex in Yokohama, the JFE Group has begun to develop directional solar mirror technology and is part of the Japanese Ministry of Environment's 2010 plan to tackle global warming. However, the outbreak of the nuclear crisis has created an urgent problem in the development of new renewable energy sources. In cooperation with the Japan Applied Energy Research Institute, Mitsubishi Optical Co., Ltd., the JFE Group completed the use of solar photovoltaic cells in August 2011. High-light tower solar system installation technology.

However, the solar market is still a challenge. The once-rising Japanese solar cells suffered from low prices from Chinese manufacturers. Afterwards, the Japanese government promoted the industry through new incentive measures and changed the energy landscape. For JFE Group, the investment in the construction of solar power plants will exceed the impact of Japan's power grid recovery. The company has invested more than US$370 million to build a cutting-edge solar power facility like Yokohama, but it will achieve its goal in 2015 at least. It still needs 610 million U.S. dollars.