What is the Goal of Your Research?

Human beings have consumed a large amount of energy resources such as coal, oil and natural gas since the industrial revolution. These resources will run dry some day in the future, and therefore it is important for us to secure other energy resources beforehand. One of the major candidates is the power generation technology using renewable energy, such as solar and wind power generation. Even in Japan, there are high expectations with this technology thanks to its environmental friendliness and safety. However, the current technology is unfortunately insufficient and we cannot rely only on power generation from renewable energy and stop all of the thermal and nuclear power plants. This is because the electric power system must ensure simultaneity of demand and supply where the same amount of electricity must be generated and consumed simultaneously, but the amount of electricity generated from renewable energy depends on the weather (Figure 1). Imagine if you could watch TV only when the wind blows or the sun is up. Could you live like that? Our laboratory is developing a technique that makes it easier to use renewable energy by applying battery and smart grid technology.

 

Leveling Power Generation Output for Renewable Energy Using Batteries

Have you heard of headphones with the noise canceling function? When used on a train or in noisy environment, it generates audio signals that counteract the external noise and outputs them together with the music that is playing. As a result, the user can feel as if he/she were listening to the music in a quiet environment with little noise (but this device is a little expensive). Our laboratory is trying to do something similar with power generation using renewable energy. We are developing a control technique that charges and discharges a battery (Figure 2) so as to counteract the fluctuation in power generation (Figure 1) in order to smooth out and stabilize the total power generation amount as shown in Figure 3.

Figure 4  Wide area control system for renewable energy power plants


Figure 5  DC micro grid installed in Obihiro city

However, a battery is still expensive and therefore cannot be installed at each power generation facility. For this reason, we are conducting research to connect multiple solar and wind power plants in Hokkaido by using information and telecommunications networks (Figure 4) and installing one large battery for all facilities. This integration will reduce the required battery size because any increase in power output from a facility can counteract any decrease in power output from another facility.

 

Effective Use of Renewable Energy Using Smart Grid Technology

Changing the use of electricity according to the weather is certainly troublesome and inconvenient. However, if the consumption of electricity is automatically managed in a smart manner where we do not notice any change and to the extent that our comfortable lifestyle is not impaired, that does not pose any problems, right? The supporting technology for the electric power system as described above is smart grid technology, which has been attracting attention recently. For example, the smart grid system predicts the weather and our electricity usage pattern for tomorrow. It plans a charge schedule for the batteries and electric vehicles and a work schedule for washing machines, air conditioners, etc., so that the highest energy efficiency will be attained. It controls all equipment and devices according to the schedules. Our laboratory has developed this type of system and installed it in a building in Obihiro city, Hokkaido. And we are now measuring its effects.

 

What Will be Your Next Goal?

Biomass (collective term for biological resources drawn from animals and plants) is another renewable energy. Biomass can be used for power generation by burning it directly or by using the alcohol or gas produced from it. The biomass-firing power generation is controllable, in contrast to solar or wind power generation. In addition, not only electricity, but also heat is produced simultaneously (cogeneration). Particularly in Hokkaido, there is abundant biogas produced from the excrement of cows and horses. As described above, a battery is still expensive. Therefore we have just begun research using output-controllable biogas power generation instead of batteries.