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Bio-ethanol can be produced from several type of biomass, and the CO2 emission of bio-ethanol is low compared with gasoline. Bio-ethanol is a high octane fuel, therefore, it has characteristics that allow it to burn at a high compression ratio condition. However, bio-ethanol is usually refined to be high purity ethanol (>99.5%). It requires much energy to refine; thus large-scale refinery plants are needed, increasing the cost of refining bio-ethanol. High purity ethanol (>99.5%) can be refined after fermentation and a distillation. If hydrous ethanol can be used as a fuel for engines, the distillation process can be simplified. As a result, the costs of refinement can be reduced. An innovated engine can be developed by using hydrous ethanol as the fuel because three highly efficient methods can be combined. First, exhaust heat can be recovered by the steam reforming of hydrous ethanol. Second, the reformed gas, which contains hydrogen, can be combusted under dilute conditions.

Hydrogen produced from regenerative sources has the potential to be a sustainable substitute for fossil fuels. A hydrogen internal combustion engine has good combustion characteristics, such as higher flame propagation velocity, shorter quenching distance, and higher thermal conductivity compared with hydrocarbon fuel. However, storing hydrogen is problematic since the energy density is low. Hydrogen can be chemically stored as a hydrocarbon fuel. In particular, an organic hydride can easily generate hydrogen through use of a catalyst. Additionally, it has an advantage in hydrogen transportation due to its liquid form at room temperature and pressure. We examined the application of an organic hydride in a spark ignition (SI) engine. We used methylcyclohexane (MCH) as an organic hydride from which hydrogen and toluene (TOL) can be reformed. First, the theoretical thermal efficiency was examined when hydrogen and TOL were supplied to an SI engine.

In this study, the possibility of real-time HCCI control in a multi-cylinder gasoline engine was examined. Specifically, we applied a multivariate analysis based on an experimental design of quality engineering, and picked out several engine parameters which influence gasoline HCCI combustion stability. We clarified the characteristics of engine parameters in a gasoline HCCI operation area and propose the control concept: The internal EGR control is applied to multi-cylinder control by using the variable valve system, and air-fuel mixture control is applied to each-cylinder injection control while keeping the mixture homogeneous. Combustion conditions and engine out A/F need to be detected and fed back individually for each cylinder. With the proposed concept, it is possible to construct a real-time HCCI control system in a multi-cylinder gasoline engine.