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What is renewable energy?

This article is originally posted by Hinatao Energy in Japanese, translated and added some data/text by Japan Living Guide.

Energy is part of the everyday life we take for granted. Currently, oil, coal and natural gas are the main energy resources used in Japan, but in recent years, renewable energies have been attracting attention along with efforts to protect the global environment. But what exactly is renewable energy? And how does it affect our lives?

In this article, you will learn about energy, including the advantages and disadvantages of renewable energy and the challenges Japan faces in terms of energy resources.

What is renewable energy?

Energy that supports our daily lives, such as electricity, city gas and petrol, is produced from a variety of resources. Energy resources are broadly classified into fossil fuels, such as oil, coal and natural gas, which may have a possibility that they eventually run out, and renewable energies, such as solar, wind and geothermal power, which continue to exist in the natural world.

Renewable energies accounted for approximately 18% of Japan's total electricity generation in 2019 according to IEA database, investigation by the Agency for Natural Resources and Energy. The Government aims to increase the share of renewable energy to 22-24% by 2030. Amidst serious environmental problems worldwide, moves are underway in Japan to make renewable energy the country's main source of power.

Before exploring why the government has been trying to promote renewable energy, we first briefly explain the characteristics of 'renewable energy' and its advantages and disadvantages.

Characteristics of renewable energy

Currently, there are seven types of renewable energy sources.

(1) Solar power
(2) Wind power
(3) Biomass power (organic matter derived from plants and animals)
(4) Hydroelectric power
(5) Geothermal power
(6) Solar thermal power
(7) Atmospheric heat and other naturally occurring heat

The three criteria for renewable energy are that it is not depleting, it exists everywhere and it does not emit carbon dioxide. As power is generated using the power of nature and does not emit carbon dioxide, it is increasingly attracting attention as an environmentally friendly and future-proof power generation method.

However, renewable energies are characterized by their susceptibility to the effects of the natural world, such as seasons and weather. As a result, it is not possible to generate power in a stable manner.

Differences in energy self-sufficiency between Japan and the rest of the world

Energy self-sufficiency refers to the proportion of energy needed for daily life and economic activities that can be secured within a country. So what is Japan's energy self-sufficiency ratio? in 2018, Japan's energy self-sufficiency ratio was 11.8%. The rest is dependent on imported resources such as oil, coal and natural gas.

See the graph below. Japan's energy self-sufficiency rate is very low compared to Western countries. European countries are connected by land, so they can import and export energy by connecting power lines and pipelines with neighboring countries, but the fact that the island nation of Japan has to transport energy from across the sea is also related to its low self-sufficiency rate.

Source: Agency for Natural Resources and Energy


In addition to renewable energy, Japan also has nuclear power. Nuclear power used to be a valuable source of energy due to its ability to recycle fuel and accounted for much of Japan's energy self-sufficiency, but since the Great East Japan Earthquake of 2011, nuclear power plants have been shut down and Japan's energy self-sufficiency rate has dropped significantly.

source: Agency for Natural Resources and Energy

Japan's energy self-sufficiency rate

Japan relies on Middle Eastern countries for 80% of the crude oil it imports, which accounts for around 40% of its energy resources. The Middle East region faces a number of problems, such as unstable international conditions, which make the supply of crude oil unstable and prices soar depending on the political situation in the region. Oil is a fossil fuel that may have a possibility to run out and our lives would surely be impacted if oil imports were to stop. Renewable energies hold great promise as a solution to Japan's energy self-sufficiency problems.

A Comparison of percentages of renewable energy in total power generation in major nations

The percentage of renewable energy power in Japan was 18% in FY 2019. Japan ranks 6th in the world in terms of renewable energy generation capacity, and 3rd in the world for solar power generation. 

source: Agency for Natural Resources and Energy

Five renewable energies that are already being put to practical use

Here are five renewable energy sources that have already been put to use.

1. Solar power generation

Photovoltaic power generation uses solar cells, which convert light energy from the sun into electricity. These are assembled into a solar panel.

Solar power has the advantage of being easy to install, as there are no restrictions on where or in what areas it can be installed, depending on its size, and it can be installed on the roofs of private homes. Another important point to note is that they may also be used as a permanent power source in the event of a disaster.

(Below text is added by Japan Living Guide)

Disadvantages include the problems that arise when photovoltaic installations are damaged due to such as natural disasters. Photovoltaic installations can still generate electricity when exposed to light, even if they are flooded or damaged. Depending on the damage, the waste may need to be properly disposed of as industrial waste to prevent the release of hazardous substances, and solar panel manufacturers also need to actively disclose information.

The Ministry of Economy, Trade and Industry is currently studying the need for a recycling system, based on an understanding of the amount of waste expected to emerge in the future, the cost of disposal and demand trends for recycled materials.

2. Wind power generation

Wind power is a renewable energy source that uses the power of the wind to generate electricity by rotating giant blades shaped like wind turbines. Because the equipment is more than 100 m high, it requires a large area of land, making it difficult to install in residential areas or densely built-up towns, so it is often installed by the sea or on top of mountains. When favorable conditions are met, it is said to be an economically beneficial renewable energy source, as it can be as low-cost as thermal power generation.

On the other hand, there is a disadvantage: if the weather is calm and the wind is weak or too weak, power cannot be obtained and therefore no electricity is generated. Therefore, they are suitable for locations where the wind blows steadily throughout the year, and recently plans have been made to install them on the sea.

3. Biomass power generation

Biomass power generation uses the heat generated when burning biological resources such as wood waste, burnable rubbish and livestock dung to generate electricity. Normally, carbon dioxide is emitted when things are burnt, but power generation using biomass resources as fuel is based on the concept of being 'carbon neutral', meaning that it has no effect on the increase or decrease in carbon dioxide emissions.

Carbon neutrality is the idea that the same amount of carbon dioxide is absorbed by the biomass resource before combustion as the carbon dioxide produced during combustion, resulting in a plus-minus of zero carbon dioxide emissions into the atmosphere. The main advantage is that waste can be used as energy. The disadvantage is that the cost of collecting, transporting and managing the resources is an issue.

4. Hydroelectric power generation

Hydropower is a renewable energy source that utilizes the energy generated when water moves from a higher to a lower level. Giant dams are representative of hydropower. In Japan, where rainfall is abundant and water is plentiful, almost half of all renewable energy comes from hydropower. It is the cleanest renewable energy source, as it does not produce carbon dioxide or any other air pollution-causing substances. However, the construction of large dams has a major impact on the natural environment and is costly, and the amount of electricity generated depends on the amount of rainfall.

5. Geothermal power generation

When rain that falls on the ground reaches the underground magma layer, it turns into steam and accumulates deep underground. The mechanism of geothermal power generation is to dig a well and generate electricity by venting this steam. Because it utilizes the heat from the magma inside the earth, it is a stable and endless resource that is unaffected by time or the seasons.

However, the cost of construction and development of power generation facilities can be high. In Japan, which is located in a volcanic zone and is rich in geothermal resources, the development of geothermal power generation has not progressed due to the fact that many suitable sites are located in national park reserves and hot spring areas.

Renewable energy influences the future of the planet

While environmentally friendly renewable energies have many advantages, they also have disadvantages depending on their power generation methods and facilities, and their introduction as an alternative to fossil energy has been slow to take off. However, with advances in technology, the development of renewable energies is steadily increasing in practicality while solving problems one by one. Energy issues affect not only Japan but also the future of the planet. There are high expectations for renewable energy as a means of solving environmental problems. It is an important theme that is closely related to our daily lives, so it is important to take an interest in it on a daily basis.

HINATAO ENERGY provides gas and electricity services in English in and around Tokyo and with their Sustainable Plan, your electricity consumption will be carbon neutral, resulting in net zero CO2 emissions. Please contact them if you would like to find out more about their services.

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