No. 23: On new type fuel cells (1/2) (December 1, 2011)

Basically, there are three kinds of fuel cells depending on electrolyte employed, and the operation temperature varies with the kind of electrolyte. The solid high molecule type that uses polymer electrolyte has an operation temperature of about 80 degrees centigrade. Commercialized in 2009, it uses hydrogen as fuel. It has generation efficiency of about 36%. The phosphoric acid type that uses phosphoric acid solution as electrolyte has an operation temperature of about 200 degrees centigrade. Commercialized in 1998, it uses hydrogen as fuel. It has generation capacity of about 38%. The solid oxide type that uses oxide as electrolyte has an operation temperature of about 800 degrees centigrade. It will be commercialized late 2011, and it uses hydrogen and city gas as fuel. It has generation capacity of about 41%.  

The phosphoric acid type launched in 1998 is a system suitable well for large power demand in the level of 100 kW, and it is installed in schools and office buildings. Lots of efforts are being made to develop the solid oxide type that will be put on the market as the second-generation Ene Farm. The big difference between the solid oxide type and solid high molecule type for household use is the operation temperature. Because the solid oxide type operates at such a high temperature of 800 degrees centigrade, it has various advantages over the solid high molecule type. (To be continued)   

No. 22: On fuel cell Ene Farm (November 30, 2011)

Household fuel cell was put on the market in 2009 under the uniform name of Ene Farm. The latest thermal plant generates 53 power out of fuel with 100 energy amount, and the remaining 47 is heat waste. Out of the 53 power, 48 is delivered to households because loss incurred in power distribution is unavoidable. Whereas, Ene Farm that generates by dint of the reaction between hydrogen collected form gas and oxygen supplies a household with 36 power and 45 heat (hot water) because it uses waste heat generated in power generation.

The present Ene Farm employs a solid polymer molecule fuel cell that uses high molecule electrolyte. In the initial stage, an Ene Farm was priced at 3,500,000 yen and a subsidy of 1,400,000 yen was available for the purchase. It is now 2,800,000 yen with a 1,050,000 subsidy. The price reduction can be attributed to reducing the generation capacity from 1 kW to 750 watts and decreasing the number of parts, in addition to the technological development to optimize the system to each household.

About 5,000 Ene Farms were sold in 2009. The sales increased to 7,000 units in 2010. Because of the growing concern since the Fukushima disaster, the sales as of July 7 2011 were about 8,000 units. Because a taxation incentive is offered to those who purchased an Ene Farm, the sales are expected to grow further in the future. In addition to decreasing a unit price, what is required is to increase the generation efficiency and develop a system to install an Ene Farm in a housing complex where demand is averaged. 

No. 21: On wind generation and offshore wind farming (November 28, 2011)

In wind generation, wind power is proportionate to the area that receives wind and to the cube of wind velocity. That is why location is a critical factor for wind generation. At present, the horizontal-axis propeller windmill is widespread because it can easily be made bigger in size, and the vertical-axis type that can generate electricity regardless of wind direction. Wind generation has been increasing presence both at home and abroad. Wind generation has a combined generation capacity of 194 million kW worldwide as of the end of 2010. The world leader in wind generation is China that has a capacity of 42 million kW, surpassing the U.S.

Japan has a capacity of 2.4 million kW at present. It has several problems with the introduction of wind generation, such as the extra cost to make the facilities resistant to typhoons and thunderstorms and a large amount of cost to acquire land for the facilities. In particular, land acquisition cost needs studies and examinations. Deforestation is necessary to build facilities and expand the roads for transportation of equipment and machinery. At the same time, health damage caused by noise and low-frequency sound if facilities are built in the vicinity of a residential area.

According to the report on potential renewable energy in Japan published by the Ministry of Environment, Japan has a potential capacity of wind generation between 24 million kW and 415 million kW. It is reasonable to estimate that Japan will have a generation capacity of 30 million kW on the condition the current efforts are made in the future. Because Japan is surrounded by the sea, offshore wind farming attracts strong attention. However, In addition to reducing the cost and developing technology, it is necessary to modify relative legal systems to foster the coexistence of offshore wind farming and ocean right including fishery right.

Wind generation is strongly characterized by regionality because of the necessity of wind. It is and will be mainly installed in northern part of Japan, such as Hokkaido and the Tohoku district. Therefore, even if wind generation accounts for only 10% of Japan’s total power demand, it will almost accounts for 100% of the power demand in northern districts. It is urgent to develop technology for the coordination of wide-range power distribution grips and the stability of power systems.   

No. 20: Small-scale hydraulic generation is spreading (November 20, 2011)

The law that asks electric power companies to purchase all electricity generated by renewable energy will be enacted next year, and the move to build a small-scale hydraulic plant through the collaboration between a local government and a private company is spreading. Nomura Agri Planning & Advisory will build a small-scale hydraulic plant in Tochigi Prefecture on trial. The company will install a generation with an output of 10 kW in two locations in the irrigation canal inside the prefecture to conduct feasibility study next spring, and commercialize the technology in 2013. The prefectural government will help the company by simplifying the complicated procedures involved in irrigation right. A subsidiary of Mitsui Mining and Smelting will build a hydraulic plant that generate electricity using water of two rivers running in its premises with an investment of 1 billion yen. Nippon Koei will start to build a hydraulic plant in Kagoshima Prefecture coming December. The plant will have a generation capacity of 460 kW and start operations in April 2013.

Japan has more than 20,000 locations suitable for small-scale hydraulic generation. Although each of them has a generation capacity less than 30,000 kW on average, they together are estimated to have a potential generation capacity of 15 million kW, about the same generation capacity of 15 nuclear power plants. Local governments that support the projects are serious about promoting renewal energy business. Because water volume does not fluctuate greatly, hydraulic generation is more stable than photovoltaic generation and wind generation in terms of output. The Ministry of Economy, Trade and Industry estimates the generation cost of a small-scale hydraulic plant at 10-35 yen per kW depending on the location. To promote small-scale hydraulic generation, the Japanese government is considering revising the river law and deregulating the procedures involved in irrigation right.   

No. 19: On photovoltaic generation in Japan (November 12, 2011)

Photovoltaic generation is expected to grow widespread as a generation technology because it is environmentally friendly. All Japanese companies involved are exerting lots of energy to develop the Japanese photovoltaic generation technology to be highly competitive in the world market. It is urgent for them to increase the energy exchange efficiency to higher than 18%. The photovoltaic generation roadmap published in 2009, it is scheduled to be increased to 20% in 2020 and 40% in 2050.

According to the estimated by New Energy and Industrial Technology DevelopmentOrganization (NEDO), it is expected that the exchange efficiency will be 20%, generation cost will be less than 14 yen per kW, and national annual output of photovoltaic generation will be 2-3 million kW in 2020, and the three figures are expected to be 40%, 7 yen per kW, and 25-35 million kW in 2050. If these targets are achieved, the area necessary for photovoltaic generation per kW will decrease drastically, making it possible to install a system in a small space.

Theoretically, the maximum exchange efficiency of silicon semiconductor prevailing most in photovoltaic generation is 27%. Accordingly, researchers are developing photovoltaic cells made of other chemical compounds. In addition, they are trying the tandem type that layers multiple materials, quantum dot type that uses fine particles, and light focusing type that collects light using lens. Currently, a new residential house can introduce a photovoltaic generation system with a generation capacity of 3 kW for about 900,000 yen (about 750,000 with subsidy). In view of the current technological progress, it may not be a dream that most houses in Japan will have a photovoltaic generation system in the future.

The large-scale photovoltaic power plant called mega solar has also been increasing presence because it can intensively control the unstable distribution grids caused by the output fluctuations. However, it creates transmission loss between the plant and households. In addition, maintenance does not create constant employment in the region. A vast land is required to build a large-scale photovoltaic power plant. 

No. 18: Nation’s biggest photovoltaic power plant will be built in Aichi Prefecture (November 11, 2011)

A total of six companies including Mitsui Chemical and Toshiba have decided to build the national’s largest photovoltaic power plant in Aichi Prefecture with an investment of about 18 billion yen. The construction will start in June 2012, and the plant is schedule for completion in September 2013. All the power generated by this plant will be sold to Chubu Electric Power Company. As the special measures law of renewable energy will be put into effect in July next year, it is likely that a large size project of this kind is supposed to start in succession in Japan.

The mega plant will be built in the 820,000-square-meter idle land owned by Mitsui Chemical. Solar panels with a combined capacity of 50,000 kW will be laid on the area. A wind generation plant with a capacity of 6,000 kW will also be built in this area. The plant will be able to generate power sufficient to satisfy the demand of about 19,000 households. There are two mega photovoltaic power plants at present. The plant in Sakai near Osaka has a capacity of 28,000 kW, and the plant in Kawasaki near Tokyo has a capacity of 20,000 kW. The new mega plant in Aichi Prefecture will have the nation’s largest, surpassing these two mega plants.

The special measures law to be enacted next July asks electric power companies to purchase all amount of power generated by renewable energy at a relatively high price for the next 15-20 years. The specific amount and specific period for the purchase will be decided early next year.  

No. 17: Using earth thermal for the air-conditioning of convenience stores (November 10, 2011)

Japan’s largest convenience store chain Seven-Eleven will start an experiment to use earth thermal for the air-conditioning of its stores. Using the piles to be driven into the store underground, the system will circulate water that is warmer than outside air in winter and cool in summer, thereby reduce the power used for air-conditioning by about 30%. In the initial stage, the company will install the system in three stores. The experiment will start early next year. The system was developed by JFE Engineering.

According to JFE Engineering, earth thermal is constant at 17 degrees centigrade all the year round in Tokyo. Using the circulating water, the system lets heat go in the ground in summer and collects heat in the ground in winter. To build a convenience store on soft ground, it is necessary to drive 20-30 piles, each of which is 10-20 m long, into the ground. The system fills the piles with water and inserts pipes for circulating water connected to the outdoor equipment for air-conditioning in the piles. As Seven Eleven will build about 400 stores on the soft ground, it will introduce the system to them depending on the results of the experiment. Since the system requires an initial investment of 7-8 million yen per store, reducing the price through mass production is vital for its spread. New Energy and Industrial Technology Development Organization will bear two thirds of the cost necessary to introduce the system into the three stores.

No. 16: On photovoltaic generation in Japan (November 9, 2011)

A module of photovoltaic generation is installed on a roof with a power conditioner, a power monitor, and electric wiring. In the early stage, the price of silicon thin film used as the semiconductor accounted for the largest part of a unit price. Thanks to technological innovation, the price of silicon thin film has been decreasing. However, as silicon materials are growing higher in price because of speculation, the development of silicon-free photovoltaic generation invites a wide attention lately.

Output of photovoltaic generation depends on the generation efficiency and amount of sunlight. The lower the temperature is, the higher efficiency a semiconductor exhibits. This is why the cold area is suitable for photovoltaic generation. However, photovoltaic generation cannot generate power when snow covers the generation module in the cold area. Naturally, photovoltaic generation generates power only in daytime, and its output peaks at 12:00 noon. Therefore, a household has surplus power in daytime and shortage in nighttime. It is totally impossible to adjust power supply and power demand in photovoltaic generation. Electric power companies purchase surplus power created in daytime and provide the shortage to households in nighttime to adjust the gap.

The present purchase system works well because photovoltaic generation accounts for merely 0.5% of all power supply at present. However, as photovoltaic generation is expected to increase the share to 20-30% in the future, the system to store power by dint of a storage battery is critical. It is not too much to say that the future of photovoltaic generation depends on the development of a high performance and highly efficient storage battery.

No. 15: On pumped storage generation in Japan (November 8, 2011)

Pumped storage generation is the system to generate electricity using the potential energy between the upper reservoir and lower reservoir. It pumps up water in the lower reservoir to the upper reservoir using surplus power when power supply is not tight. Therefore, it needs facilities to store water. Tokyo Electric Power has the maximum electricity supply of 55 million kW, of which 7 million is from pumped storage generation.

Pumped storage generation is mostly large-scale. For example, the plant that Tokyo Electric is expanding in Gunma Prefecture will have the world’s largest generation capacity of 2,820,000 million kW, a drastic increase from the current 470,000 kW. This plant will start operations after 2020. However, as the pondage of the upper reservoir means the maximum generation capacity, the new plant can operate for nine hours per day at the longest. Because of the limit of the pumpage volume, it is impossible to operate the system to 100%. Before the Fukushima disaster, most power used to pump up water during nighttime was nuclear power, but power from thermal power generation is currently used instead.

The energy efficiency of pumped storage generation is about 70%. That is, 30% of thermal power used to pump up water in nighttime is wasted, and the amount of carbon dioxide emitted by thermal generation increases. In addition, power generated by old and inefficient thermal power facilities is currently used for pumped storage generation. Despite these facts, however, there is no suitable and promising technology to replace pumped storage generation. It seems the best way to operate pumped storage generation as an emergency measure in extreme hot days when power supply is rather tight.  

No. 14: On hydraulic power generation in Japan (November 7, 2011)

Hydraulic power generation has a long history in Japan, and Japan maintains a high level of technology in hydraulic power generation. The run-off-river-type power generation that draws river water can replace nuclear power generation, but most locations suitable for large capacity run-off-river-type power generation have already been developed in Japan. The initial investment in facility construction has a large share in generation cost in case of hydraulic power generation. Although generation equipment has generally has a life of 40 years in power generation, more than half of the equipment currently used in hydraulic power generation has been operating for more than 60 years.

It is possible to lengthen the life by proper maintenance, but a large civil engineering work is necessary in consideration of residents living in the watershed to discharge accumulated earth and sand that flow in a dam reservoir. In Japan, there are 2,500 locations for possible development of hydraulic power generation with a total generation capacity of 8,900,000 kW that is equivalent to the generation of nine nuclear power plants. However, most hydraulic generation plants in operation has a generation capacity of several tens of 10,000 kW on average, but newly hydraulic generation plants will have a capacity of 3,500 kW on average. That is, constructing a new plant will results in a high generation cost. In addition, it takes much time to conduct research on environmental assessment and get consensus from local residents. In view of the slow decision of the central government, hydraulic power generation cannot be a short-term solution for the energy problem.   

No. 13: Race to develop a new system for wave activated power generation (November 4, 2011)

Three companies involved in the development of a wave activated power generation system are intensifying their efforts to introduce a new system. They plan to finish the basic design in two years and start a substantiative experiment on the sea in 2013 with a view to achieving a generation unit cost of 40 yen per kW by 2015. Mitsui Engineering and Shipbuilding will improved the system developed by Ocean Power Technologies of the U.S. to make it suitable to the sea around Japan. The new model will be 8.5 m wide and 30 m long with a capacity of 80 kW.

Mitsubishi Heavy Industries Bridge andSteel Structures Engineering will develop a system that uses waves coming to breakwaters to run a turbine with the help of changes of water surface and pressure in alliance with Toa Corporation. The equipment for the system is 20 m wide, and it projects about 20 m from the breakwater. Hitachi Zosen and a joint venture company in Kobe will develop a gyro system that generates the power when rotating circulate plates comes back to the original position by virtue of waves. They plan to build two units of generation equipment, each of which has a capacity of 100 kW. Japan started the development of a wave activated power generation system since 1975, but is still unsuccessful in translating it into practical applications because of the high generation unit cost. Each of the three groups addresses the development as a project led by New Energy and Industrial Technology Development Organization (NEDO) and plans to realize a generation unit cost of 20 yen per kW by 2020.