We are developing technologies that make use of biomass in a bid to reduce greenhouse gas emissions. Biomass is a generic term for plant and animal-derived organic resources*1 (excluding fossil resources) that can be recycled into energy or material. Burning biomass releases CO2, but CO2 absorbed from the atmosphere by plants during photosynthesis offsets this release. This is the greatest advantage of using biomass.
It can be used as an energy source in a number of ways, such as obtaining heat or electricity with the use of steam generated by burning it, and using biogas acquired from fermented biomass for combined heat and power (CHP) systems*2.
We plan to promote the wider use of biomass and its diffusion by working on the biogas utilization technologies we have developed through combustion of city gas and biogas as well as technologies for extracting biogas through more reasonable and efficient methane fermentation of biomass, such as food waste, and upgrading biogas to a higher quality gas.
*1 Examples are rice straw, farm, forestry and fishery products like livestock excrement, food waste, sewage sludge and wood chips.
*2 Gas engine-based CHP systems generate electricity and recover waste heat generated as a by-product.
Developing Biogas Utilization Technologies
The Tokyo Gas Group possesses technologies for converting biomass such as food waste and sewage sludge into gas for use as fuel for boilers and power generation and uses biogas that builds up at customer sites mainly as fuel for cogeneration equipment. As biogas is a lean fuel comprising about 60% of CH4 and 40% of CO2, specific power generators are needed. We were the first in Japan to begin to refine biogas from food waste, adjust its calorific value and odorize it so that it could be injected into city gas pipelines. In fiscal 2017, we received 485 thousand m3 of biogas derived from food waste (equivalent to about an 827-ton reduction in CO2 emissions).
How Biogas Is Fed into Gas Pipelines
Test equipment for refining biogas at North Yokohama Sludge Recycling Center
Construction and Operation of Hydrogen StationsWe construct and operate hydrogen stations to popularize fuel cell vehicles (FCVs) and help establish the infrastructure for supplying hydrogen. We want to create a hydrogen society that makes use of zero-emission hydrogen energy. CO2 emissions for which FCVs are liable do not differ significantly from those for electric vehicles in terms of mileage, and the use of FCVs helps to reduce environmental impact.
*1 Source: Agency for Natural Resources and Energy
*2 Three automobile makers: Toyota Motor Corporation, Nissan Motor Co. Ltd. and Honda Motor Co. Ltd.; five infrastructure businesses: JXTG Nippon Oil & Energy Corporation, Idemitsu Kosan Co. Ltd., Iwatani Corporation, Toho Gas Co. Ltd. and Air Liquide Japan Ltd.; and two others including financial investors: trading company Toyota Tsusho Corporation and financial firm Development Bank of Japan Inc.
|Time||Outline||Hydrogen Supply Method*3|
|May 2003||Senju Hydrogen Station opened in a pilot R&D project||On-site|
|December 2010||Haneda Hydrogen Station opened in a pilot project. (Japan’s first hydrogen station with a natural gas stand (until 2015)||On-site|
|December 2014||Nerima Hydrogen Station opened as the first commercial station in the Kanto region||Off-site|
|January 2016||Senju Hydrogen Station converted into a commercial facility||On-site|
|February 2016||Urawa Hydrogen Station started commercial operations||On-site|
|February 2018||Tokyo Gas set up JHyM with other companies to promote hydrogen stations|
*3 Hydrogen stations supply hydrogen produced on location from city gas (on-site method) or hydrogen produced elsewhere (off-site method).
Development of Hydrogen TechnologiesTokyo Gas conducted research and development on hydrogen stations for supplying hydrogen to fuel cell vehicles as a participant in a New Energy and Industrial Technology Development Organization (NEDO) project on research and development of hydrogen utilization technology from fiscal 2013 to fiscal 2017. As NEDO is expected to carry this project forward, we will continue exploring ways to control the quality of hydrogen fuel injected into FCVs, assess the accuracy of hydrogen injection quantity measurement and inject hydrogen into FCVs other than passenger cars, such as buses and motorcycles. In addition, we will help formulate industry guidelines for these methods in the hope of incorporating them into international standards. We are further exploring efficient ways to run commercial hydrogen stations and reduce their maintenance costs.
Improvement of Power Generation Efficiency and Total EfficiencyCHP systems boast significantly better power generation efficiency, approaching 50% for large-scale systems with an output of 5,000 kW or higher and exceeding 40% for medium-size systems with an output of 300 kW to 1,000 kW. This has resulted from technological development, such as the mirror cycle method*1 and fine, cylinder-wise control of combustion.
*1 The focus of this method is on improving heat efficiency by making the cylinder expansion ratio greater than the compression ratio through a change in the cam profile shape in order to delay the timing of valve closing, unlike the conventional Otto cycle, in which the cylinder compression ratio and expansion ratio are the same.
As of March 2018, we are continuing to test a 5 kW-class commercial fuel cell installed at the Arakawa Sogo Sports Center in Tokyo’s Arakawa Ward. The test under actual conditions of 5 kW-class commercial fuel cells is being conducted under an agreement concluded between Arakawa and Tokyo Gas at the end of 2015. This is the first test of its kind at a public facility in Japan.
Electricity generated by a commercial SOFC powers first-floor lighting at the center, while waste heat is used to produce some of the hot water for locker room showers. During the test, a monitor displays the amount of electricity generated by the SOFC, and visitors can experience the hot water. The project is intended to raise awareness of fuel cells and the contribution they can make to the creation of a low-carbon society.
Attendant explaining how a 5 kW-class commercial fuel cell is tested
We have developed technologies to improve the efficiency of SOFC power generation and confirmed the world’s first 65%-level*2 power efficiency rate on a lower heating value (LHV) basis by a small-output, 5 kW-class fuel cell hot box.
We combined three technologies—building double fuel cell stacks, recycling fuel and achieving thermal self-sustainability with unused fuel—and verified their effectiveness.
With these technologies, we will accelerate research and development to build a prototype so that we can contribute to creating a low-carbon society upheld by the advanced use of city gas with a marginal impact on the environment.
*2 Excluding the energy to operate the fuel cell when it is incorporated into a power generation system, and on a direct-currency transmission-end efficiency basis for use by customers; with an auxiliary loss of 6% and DC-AC inverter loss of 5%.
In a joint study, Kyushu University’s Next-Generation Fuel Cell Research Center (NEXT-FC) and Tokyo Gas have successfully developed an innovative concept to improve dramatically the electrical efficiency of solid oxide fuel cells (SOFCs) to over 80% on a lower heating value (LHV) basis and improving the mechanism, for the first time in the world. This achievement was published in July 2015 in Scientific Reports, Nature’s sister online publication.
Super-efficient energy conversion from fossil fuel to electricity is expected to make a major contribution to reducing CO2 emissions and provide the core energy technology for creating a highly environmentally sound, smart energy society. In addition, super-efficient power generation systems are potentially far more adaptable to market demand because they produce so little waste heat during the power generation process that they can eliminate the need to use waste heat.