Online Exclusive: A conversation with Yoshinobu Tsujikawa, Kyosemi Corporation.
Japan currently leads the world in solar power technology. Japan not only produces half the total solar cells made in the world, it also exports 30% of these cells, with expected demand for 20% increases per year. Japan-based companies have advanced not only conventional photovoltaic cell production, but also novel methods for harnessing solar energy. Kyosemi Corporation’s Sphelar technology consists of a matrix of tiny, spherical-shaped solar cells. The spheres are designed to absorb sunlight at any angle, and therefore do not require motorization for tracking the sun. Based on their geometry, Sphelar cells even optimize the use of reflected and indirect light, and have been shown to convert energy with close to 20% efficiency – beyond most flat photovoltaic technologies. Its flexible disposition also makes Sphelar appropriate for applications at a variety of scales, including facade glazing and mobile electronic devices.
Please tell me about your career history.
Before I joined Kyosemi, I worked at Mitsubishi Chemical Industry, which has a partnership with Monsanto. I actually visited the Monsanto headquarters in St. Louis thirty years ago, and I had much training in gallium arsenide-based semiconductors. Mitsubishi Monsanto Chemical Corporation is located in Tsukuba, and I produced single crystalline gallium arsenide, gallium arsenide phosphide vapor phase technology, and gallium arsenide substrates, which are used to emit light.
When did you join Kyosemi?
In May of 2002. At that time, I transferred to Hokkaido Semiconductor, and in 2003, I returned to Kyosemi Corporation. That same year, Kyoto Semiconductor changed its name to Kyosemi Corporation. I have since been involved in developing solar technologies at Kyosemi Corporation.
What is the relationship with Hokkaido Semiconductor?
It is a subsidiary of Kyoto Semiconductor—a factory located in Kamisuganawa which manufactures LEDs and photodiodes. The microgravity utilization center is in Eniwa city.
How has the solar (and semiconductor) industry changed since the beginning of your career? Has the technology become more efficient?
The efficiency is related to the physical properties of the particular cell used. Depending on whether you are studying single crystalline silicon, amorphous silicon, or polycrystalline silicon, the efficiency of energy conversion is different.
When was Sphelar first developed?
Kyoto Semiconductor was founded in 1980. Founder and CEO Josuke Nakata began developing an idea for a spherical solar cell in 1993 when he was in the Kamisunagawa district in Hokkaido. Sphelar is the first spherical single crystalline semiconductor to be grown under micro-gravity conditions, and it has an energy-conversion efficiency of close to 20% in the laboratory. At the time Nakata was conducting his preliminary experiments with Sphelar, he was invited by the Kamisunagawa governor to discuss this new energy technology in light of the Hokkaido coal plant closures ordered by the Japanese government.
What year was this?
Between 1980 and 1990, Japan decided to curtail coal production because of its nature as a dirty and limited resource. Unfortunately, many coal miners lost their jobs, and they could not easily transition to other work. The local government has been consulting with a variety of experts regarding suitable replacements to coal energy.
The coal workers who lost their jobs—can they work in a new industry?
The fabrication and assembly of our technology is mainly carried out in Eniwa, which is an urban location. Most of the coal mines were located in the countryside. Also, we are planning to transfer the assembly of our products to foreign countries, to be closest to the consumer.
Japan is currently the leading producer of solar technology in the world. Could you speak more about the government’s support for solar energy?
When the coal mines were shut down, NEDO (the New Energy and Industrial technology Development Organization) was born. NEDO is Japan’s largest public R&D management organization for promoting the development of advanced industrial, environmental, new energy and energy conservation technologies, and they give generous support in the form of grants to select companies who are developing promising new technologies.
Does the Japanese government continue to support your research & development efforts?
Yes, Kyosemi continues to receive funding from NEDO. They support our exhibitions in various conferences and expositions.
I read recently that China is becoming a more capable player in the solar arena. Would Kyosemi Corporation entertain partnering with a Chinese manufacturer? Perhaps you could decrease your manufacturing costs.
Many people think that is a good idea, and we have considered it. However, Sino-Japanese relations are still tenuous in terms of sharing intellectual property, so we will abstain for now.
I read that Japan wants 10% of its energy to come from solar power in 2030.
According projections by Mizuho Securities, Japan will be able to generate 5 GW from solar power by 2010 based on the current growth rate. That compares favorably with 3 GW projected for Europe.
By 2020, Europe is expected to produce 35 GW, and China 2 GW of solar power. Why is there no projection for Japan according to this study?
It is a matter of national character. China and European countries have many policies based on extrapolating current data.
Do the Japanese think this kind of policy is important?
Yes, but Japan is conservative because we have no idea what 2020 will bring, especially since Japan’s resources are very limited, and it is difficult to predict how the peak oil crisis will affect world energy markets.
Where is Sphelar currently used?
Originally, we wanted to install Sphelar modules on building rooftops, but the assembly of rooftop installations proved to be difficult. Moreover, it was complicated to make such systems, which tend to be large in scale. Therefore, we have shifted our focus to the development of small, low power applications such as portable consumer electronics.
Such as wearable solar-powered devices?
Wearable is a good idea, but the problem there is durability. Clothes move a lot and require washing, so the wiring becomes the weak link.
Then what kind of applications?
SphelarVoice is one example. Laurie Anderson designed a device called the AimuletLA for the Aichi Expo in 2005, and it utilizes SphelarVoice technology. The AimuletLA is a small device, slightly larger than a credit card, which enables visitors to learn information about their environment. While the device delivers a low-volume audio signal to the user, it requires no battery. One may simply point the AimuletLA at an item of interest in an exhibition powered by SphelarVoice technology, and infrared light projected by Sphelar modules carries audio information that is decoded by the card. The AimuletLA is perfect for museum tours, for example, because visitors may hear guided audio information without worrying about bulky devices or batteries. This technology is now commercialized and has become very popular.
The low-power technology is very beautiful. What about jewelry? Until now, jewelry has only been art. If it could also generate energy, it would be very interesting—”functioning body art?” Maybe you could do a Sphelar fashion show and Japanese designers could create jewelry with it.
That is an interesting notion. Kyosemi has been developing the technology for more pragmatic applications thus far. For example, we have produced hearing aids for indigenous people in Africa. The Sphelar-powered hearing devices assist communication by transmitting audio vibrations via bone in the ear canal.
What about larger scales?
Sphelar dome modules may be connected to form a network, and they can communicate to each other via electro-waves. Applications include crop monitoring in agriculture, site security, handicapped access, and visitor way-finding. Like SphelarVoice, visitors can learn information about a particular context, whether at the scale of an exhibition or a city. We call it a Sensornet, or sensor network, which is inherently battery-free. Have you heard of ubiquitous computing? I heard the word “pervasive?” is more popular in the West, but we Japanese like “ubiquitous.”
What about cars? Could they utilize Sphelar technology?
I think so, but we are not currently studying that. There is certainly a possibility, however.
Are you considering integration in buildings again?
Yes, the development of building-integrated photovoltaics (BIPVs) is our final goal, but it requires a large area of the Sphelar modules. We are currently struggling with how to assemble these modules in such a large area. Eventually, we hope to increase the size of the Sphelar arrays up to the scale of utility plants and power stations.
Usually BIPVs are used in windows.
Yes, we have a flexible substrate with integrated solar spheres which we call the Sphelar Window.
What if, as opposed to glass, Sphelar could be integrated with other building materials, such as concrete or other opaque products? After all, buildings are clad with many other materials which might be utilized to harness solar energy.
This is a good idea. Some researchers from Denmark asked us to collaborate to integrate Sphelar modules in concrete, but we had no idea how to do it at the time. Unfortunately our grant fell through, but if we have the chance again, we would like to try this kind of project. Some architects in Spain are installing dome modules all over buildings, perhaps in the tradition of the flamboyant architect Gaudi.
Looking at your growth projections, the scale gradually increases, doesn’t it? Is Hokkaido the number one fabrication location?
Yes, for Sphelar cells. We are also studying the assembly of Sphelar cells for these applications in Hokkaido, and eventually assembly will move to the consumer end.
Your technology works at a variety of scales. What if you linked them all? Low-power consumer electronics connected to sensornets connected to BIPvs… it could be interesting.
Yes. Currently we are focused on providing energy necessary for life, but eventually we hope to enter the realm of art.
Read other conversations in the book Matter in the Floating World, published by Princeton Architectural Press.