eywords: renewable energy region, 100% renewable energy self sufficiency region, Sustainable Zone.
Sustainable energy zone is a phrase invented by a Chiba University research group leader Prof. Hidefumi Kurasaka. It refers to a zone where all energy requirements can be met by renewable (natural energy) created within that zone. In this case, renewable energy refers to photovoltaic (solar), wind, geothermal, biomass, and small scale hydro. The ratio of supply in respect to demand is supply rate.
Rate (available supply) = (amount of power generated by renewable natural energy in the area) / (energy demand for the people in the area)
If the supply rate is more than 100%, the area is classified as sustainable energy zone. Currently when the criteria is limited to electricity only, there are 76 municipalities in Japan classified as sustainable energy zones as July 2007 (Table 1).
The extremely high supply rates over 3000% of the two top two zones, Yanaizu in Fukushima and Kokone in Oita, are because of large scale geothermal generators built in the zone. However, overall 70% of the zones have small-scale hydroelectric plants (in stream units under 10 MW).
Yanaizu Town, Kawanuma County District, Fukushima Prefectures
Geothermal power plants are pretty common in Japan by reason of volcanic activity. Japan ranks the sixth in the terms of global geothermal electricity capacity. Totally, there are 18 major geothermal power stations in operation (Figure 1), but their aggregate output only accounts around 0.2 – 0.3% of generated electricity. In the earlier of 2009, Mitsubishi Materials Corp., J-Power, Nittetsu Mining Co. Ltd., and Kyushu Power Co. will build new geothermal power plants with government support. The development is starting in 2009. Today, Japan produces 535.2 MW (
Yanaizu Town, Kawanuma County District, Fukushima Prefecture is located in rural area which is far away from the big cities in Japan. This town became popular after Prof. Hidefumi Kurasaka announced his list of Japan’s most self-sufficient places and placed the town in the top of the list. Yanaizu ranks in the first due to its fantastic rate of geothermal energy generating at 3290% (Figure 2). The second place is achieved by Kokone Town Kusu in Oita Prefecture with rate 3123%. They also use geothermal as main power to supply their energy requirement.
Hydroelectric power is Japan’s largest energy resource. Overall, 70% of the zones have small-scale hydroelectric plants (in stream units under 10 MW). Kochi Prefecture in the Shikoku Island has rivers, plentiful forests, and mountains which bring abundance of rain. Takaoka-cho, Tsuno-gun and Taiho-cho Nagaoka-gun are two cities in Kochi Prefecture which use hydro (renewable energy) as the main power in producing electricity to supply energy demand required.
Actually in the beginning, the people found that it took some effort. But after town meetings (Figure 3), they like the idea of self sufficiency and environmental benefits. Other reasons are, linking energy education with issues such as global warming and the need to reduce CO2 emission have a lot of sense to be considered.
The micro-hydro project is meant to create energy independence while also protecting local industry in the forestry and agricultural sectors. These projects are “small is beautiful”. It is a kind of deal based on community desire “don’t want to have huge dams or more concrete, just a clever way to produce energy (Figure 4)”.
On account of that, the design is adapted to the request of small scale hydroelectric power plant. One company which provide small scale hydroelectric power plants in Japan is
. Their design
Energy self sufficiency in Hokkaido
Other regions which has more 100%percentage self sufficient is located in Hokkaido Island (Table 2). The type of renewable energy used are wind and solar power. Nowadays, there will be some additional construction of RE plants in Hokkaido. They are mega solar power station 5000 kW (Figure 6) and wind power station 258 million kW (Table 3). Cape Erimo in Hokkaido has annual average wind speed 8.2 m/sec or 30 km/h (Figure 7). Wind power in Horonobe Town can be viewed in Figure 8.
When considering as a whole, Japan’s renewable energy is only 3.35%. Only 10 prefectures in Japan have rate above 10%. One of them is Oita Prefecture with the highest rate of supply at 30.8%.
Notion of Sustainable energy zones – Problems
First problem is scale. Sustainable energy zones look at individual municipality, but when considering prefectures as a whole, the highest rate is Oita Prefecture at 30.8%, with only 9 prefectures in total above 10%. As a whole, Japan’s renewable energy supply rate is only 3.35%. Therefore, the amazing supply rate, 3290% is only possible when looking at individual municipalities.
The second problem is the relationship between the supply rate and actual measures taken by the municipalities. In many cases, the high supply rate is not a result of energy measures taken by the municipalities, but rather than an outside power company has chosen that site for development. Therefore having a high supply rate does not necessarily mean the area has advance electricity measures in place, and there is no point labeling a municipality good or bad based solely on this figure.
The important thing is not only to say “wow” some places have such an abundance of renewable energy, but consider how this energy can be used to create a sustainable society. This will give new importance to these numbers and what they indicate.