One-fourth of Japan's final energy consumption is for household use, and two-thirds of that is for space heating/cooling and heating water. Research is under way to meet this heat demand using renewable energy sources such as solar and atmospheric heat.

In the summer when space cooling is needed there is an excess of heat from the sun, while in the winter when heating is needed there is an excess of cold from the sky. It would be possible to effectively use excess heat during the season it is needed if we could efficiently store it for over half a year. Accordingly, we are conducting research on technologies including those for the efficient acquisition, efficient long-term storage, and the effective use of heat from the sun and sky radiation cooling.

This system has a totally new combustion concept. It divides combustion reactions into oxidation and reduction processes, which are linked through recirculation of metal particles that act as the media for both. The oxidation process oxidizes the metal particles with air to generate heat. NOx is not generated here due to the control of oxidation temperature. In the reduction process the oxidized metal particles are reduced with fuel. This process generates no NOx, either. The amount of heat produced here is greater than that of the direct burning of the fuel, because the low-temperature heat absorbed during reduction is released during oxidation. 

Outline of MERIT system

The exhaust gas contains only water and CO₂. Lowering temperature yields pure CO₂, and the heat can be used effectively down to nearly normal temperature. In order to construct a combustion system that takes advantage of these features, NIRE is currently conducting basic research on the reaction characteristics of particles and gases, the flow properties of the system, and system evaluation methods.

Dioxins are substances that are formed unintentionally by waste incineration and other industrial processes. Their release raises worries because of their carcinogenicity and other health impacts; dioxins have broad toxicity. Already many remedial technologies have been proposed and implemented for waste incinerators, which are the main source of dioxins, but because much remains to be learned about the formation mechanisms, work is still needed on many problems such as controlling emissions in materials including that in fly ash, and the effects of waste composition on dioxin formation.

In an effort to learn about dioxin formation behavior, NIRE is conducting research for assessing the effects of organochlorines present in wastes on the formation of dioxins. There is also basic experimental research meant to elucidate the reaction mechanism by which dioxins form, and research that uses numerical analyses to theoretically understand the properties and reaction characteristics of dioxins. NIRE also conducts experimental measurements on basic reaction characteristics of dioxin related substances.

Some chemicals that enter the environment are highly toxic and biorefractory. Such compounds easily accumulate and concentrate in living tissues. In order to protect our water and soil resources, as well as human and ecological health, it is important to remove toxic chemicals from wastewater and to clean up pollution. NIRE is studying an ecological wastewater treatment and environmental remediation that uses enzymes (e.g., tyrosinase, peroxides and laccase). Potentially hazardous chemicals in wastewater are oxidized by enzymes and converted to substances that easily precipitate with a coagulant. The precipitates are later detoxified and degraded by anaerobic bacteria. To further the development of enzymatic remediation, NIRE is investigating the mechanisms by which hazardous chemicals are incorporated into soil and sediment humus by enzymatic catalysis. NIRE is also studying mass production of powerful enzymes by genetic engineering.

Nitrogenous compounds in wastewater may sometimes cause serious environmental problem if it is unintentionally released into environmental waters. This pollution problem could be recognized as algal outbreaks or dead fishes found in rivers, lakes, and coastal areas, of which phenomenon is often called "eutrophication." Nitrogenous compounds in wastewater can be eliminated by combination of various bacterial actions before it is discharged into environmental waters, if they can properly be managed in wastewater treatment facilities. It has been an issue in wastewater treatment engineering to properly sustain activities of bacteria responsible for removing nitrogen.

In general, cultivation of ammonia-oxidizing bacteria, among the microorganisms responsible for removing nitrogen, is the most difficult both in the wastewater treatment plant and in the laboratory. Our research attempts are to develop more efficient biological nitrogen removal processes mainly by maintaining organisms responsible for ammonia-oxidizing bacteria in the treatment plant. Besides, we have been carrying out fundamental studies on microbiology of ammonia-oxidizing bacteria, which provide information necessary for developing novel techniques for monitoring these organisms qualitatively and quantitatively in environments.

Technologies using ozone (O₃) to degrade biorefractory chemicals are generally divided into 2 groups: partial oxidation, which uses ozonation as a pretreatment for biological treatment, and combined oxidation, which combines ozonation with other physico-chemical treatments. Partial oxidation by ozone is an effective pretreatment for biological treatment because the biodegradability (e.g. ratio of 5-day biological oxygen demand to total organic carbon, BOD₅/TOC) of most chemicals is enhanced by ozonation, due to the introduction of oxygen into their molecular structures. Combined oxidation uses active radicals such as hydroxyl radical (OH-) instead of ozone molecules and can improve the degradation of biorefractory chemicals.

Degradations of nitrophenols and dyes are studied at NIRE to evaluate the enhance in biodegradability and the decrease in the potential for organic halide formation

Diesel-powered vehicles, which are excellent in fuel economy, are indispensable for our industry and life. However, they are among the major emission sources of nitrogen oxides (NOx) and particulate matter (PM), which are seriously degrading the atmospheric environment in Japan, especially in large cities.

 Development of new technologies to remove these harmful substances is urgently needed. Since diesel exhaust gas contains a lot of oxygen, the 3-way catalyst conventionally used for gasoline engine exhaust to simultaneously remove NOx, CO and hydrocarbons, cannot be applied. NIRE is developing a new catalytic method to reduce NOx into N₂ in the presence of oxygen and a technique to remove PM using ceramic filters and catalysts.

Atmospheric constituents such as chlorofluorocarbons (CFCs) and CFC substitutes, greenhouse gases, and nitrogenous and sulfurous compounds undergo photochemical reactions either directly or indirectly in the presence of sunlight. In a polluted area, these can build up in the atmosphere rather than eventually being removed. NIRE is especially concerned with heterogeneous processes in which particulate matter and aerosols play a role. We have found that some materials called "photocatalyst" based on titanium dioxide (TiO₂) can remove nitrogen and sulfur oxides to the levels of environmental standards (about 0.05 ppm). As this photocatalyst is activated by sunlight and regenerated by rainfall, it can purify ambient air naturally without additional energy use. Tests of these air-purifying materials are being conducted at the sides of roads with heavy traffic. Some local governments have begun considering their use.

Many of hazardous air pollutants (HAPs) such as volatile organic compounds (VOCs) and NOx are released into the atmosphere from relatively small sources, and their treatment with large-scale equipment is inefficient. However, use of mobile and energy-efficient equipment is promising.

A plasma is a physical state in which groups of ions and electrons dissociated from electrically neutral gases are randomly spaced, and it can easily activate even chemically stable substances. Nonthermal plasma affords a unique reaction medium where electron temperatures as high as 10,000°C can be obtained without raising the gas temperature. This advantage can be maximized for new and small devices with low energy consumption.

To develop a technology efficiently decomposing HAPs under nonthermal plasma conditions, this research aims at elucidation of the nonthermal plasma chemical behavior of HAPs, identification and quantification of trace byproducts, elucidation of reaction mechanisms, and development of nonthermal plasma devices optimized for the decomposition of trichloroethylene, benzene, nitrogen oxides, and organic fluorine compounds such as CFCs and HFCs.

Since CO₂ is a primary cause of global warming, the development of novel technologies for CO₂ mitigation is strongly required. Efficient chemical utilization of CO₂ emitted in large volumes from power plants, steel-making plants, chemical plants and other stationary sources would lead to the reduction of CO₂ emission, and also to the development of a new chemical industry in the future.

NIRE has been doing research mainly on (1) catalytic hydrogenation of CO₂ to produce methanol, (2) organic synthesis using CO₂ as one of the raw materials to produce various useful chemicals and (3) dehydrogenation of hydrocarbons taking advantage of the nature of CO₂ to produce olefin and styrene.

Our continuing consumption of fossil fuels produces 20 billion tons per year of CO₂ gas. About half of this CO₂ dissolves into the ocean or is incorporated into biomass. The ocean has an enormous capacity for CO₂ absorption. There are several technological options for sequestering, and thus disposing of CO₂ in the ocean. NIRE has developed the Gas Lift Advanced Dissolution (GLAD) system for sequestering CO₂ economically and without additional energy consumption. In the GLAD system, CO₂ gas is injected to a shallow depth in the ocean where it dissolves in seawater and is transported to the deep ocean through a reverse J-shaped gravity pipe.