**4. Creation technologies**

Creation technology is a technology to use renewable energy to create energy. It includes photovoltaic power generation, biomass power generation, etc. In this section, we briefly introduce these two methods of the creation technologies.

#### **4.1 Photovoltaic power generation**

A photovoltaic power generation system generally refers to a power generation system that uses semiconductors to convert light energy from the sun into electrical energy and consists of solar cell modules and arrays, junction boxes and collectors, and power conditioners, as shown in the **Figure 15**.

#### *Introduction of ZEB Technology in Japan DOI: http://dx.doi.org/10.5772/intechopen.101464*

**Figure 15.** *Conceptual diagram of a photovoltaic power generation system.*

The benefits of light energy from the sun are available everywhere, although they vary from region to region, making it the most versatile of all energy creation technologies. When installed on the rooftops of office buildings and commercial facilities, the electricity generated by the photovoltaic power system can be used to meet part of the electricity demand, since the working hours and business hours coincide with the power generation hours. In addition, the system can be promoted as a part of environmental conservation activities, which is a social responsibility of a company, and is beneficial in raising the environmental awareness of employees and securing power in times of disaster.

Particularly in the case of low-rise buildings, the rooftop area is large in relation to the size of the building, and a reasonable amount of power can be expected to be generated in relation to the power demand. On the other hand, in the case of high-rise buildings, since the rooftop area is small compared to the size of the building, the amount of electricity generated by the photovoltaic power system will be small in relation to the electricity demand. Recently, however, there has been progress in the development of "building-integrated photovoltaic systems" that can be installed not only on the rooftops of buildings, but also on walls and windows.

For the situation of photovoltaic power generation in Japan, its research and development and widespread use in Japan began with the oil crisis of the 1970s [19]. At the time, research and development were focused on the use of solar power as an alternative energy source that did not consume petroleum fuel. Later, the movement was further accelerated by global environmental issues and global warming prevention in the 1990s. In the 1990s, the first residential photovoltaic power generation systems were commercialized, and photovoltaic power generation systems evolved from being mainly used for research and development and special purposes to supplying electricity to the general public. In Japan, the feed-in tariff system for renewable energy started in July 2012. In July 2015, the government's Committee on Energy Supply and Demand (CESD) issued a report on the electricity market and presented

a supply and demand forecast for various power sources for 2030. In this energy mix, photovoltaic power generation will be responsible for supplying 7% of the electricity demand in 2030.

#### **4.2 Biomass power generation**

As shown in **Figure 16**, biomass power generation refers to the technology of generating electricity from biomass (renewable biological resources) such as wood and plant residues. The energy obtained from biomass is also called biomass energy.

When biomass is burned, as with fossil fuels, CO2 is always generated, but since plants absorb the CO2 and grow to reproduce biomass, the total amount of CO2 in the atmosphere does not increase (carbon neutral as shown in **Figure 17**).

By combining this system with photovoltaic power generation, which changes the amount of electricity generated depending on the weather and time of day, it is expected that renewable energy will be supplied in accordance with the demand for electricity.

For the situation of biomass power generation in Japan [20], the Biomass Power Producers Association (BPPA) was established in late 2016, with the aim of addressing the concerns of power producers and promoting the healthy development of biomass power producers. Biomass power generation capacity in Japan reached approximately 3.0 GW by the end of FY2016, approximately 4.0GW by the end of FY2017, and since then, it application has been steadily growing in the years.

**Figure 16.** *Conceptual diagram of how biomass power generation works.*

**Figure 17.** *Carbon neutral of biomass power generation system.*
