Experimental study of wood downdraft gasification for an improved producer gas quality through an innovative two-stage air and premixed air/gas supply approach

Economic analysis of reciprocating engine generating with bio-syngas at predicted maximum power condition

In order to effectively utilize woody biomass, which has a low abundance density, it is necessary to develop a power generation system that can convert it with high efficiency even with a small capacity as less than 2 MW. For electricity generation, it is reasonable to use a small reciprocating engine. In the case of a naturally aspirated spark ignition reciprocating engine (SIRE), the amount of aspirated gas in one cycle is determined almost entirely by the displacement. The thermal efficiency of the SIRE generally increases with the power. Therefore, to improve the thermal efficiency, it is effective to make the low heating value (LHV) of the fuel higher to increase the power of the naturally aspirated SIRE. In this paper, three methods are used to increase the LHV of the bio-syngas: 1) reducing the nitrogen density of the bio-syngas (upgrade bio-syngas), 2) adding hydrogen to the bio-syngas, and 3) adding methane to the bio-syngas. Using these fuels, 1) the conditions for high power, and 2) the costs assumed for each condition, are evaluated through experiments and estimates. The results showed that the upgrade bio-syngas, obtained by gasification with oxygen-enriched air, had the highest power and the best cost-effectiveness.

Biomass gasification, catalytic technologies and energy integration for production of circular methanol: New horizons for industry decarbonisation

The Intergovernmental Panel on Climate Change (IPCC) recognises the pivotal role of renewable energies in the future energy system and the achievement of the zero-emission target. The implementation of renewables should provide major opportunities and enable a more secure and decentralised energy supply system. Renewable fuels provide long-term solutions for the transport sector, particularly for applications where fuels with high energy density are required. In addition, it helps reducing the carbon footprint of these sectors in the long-term. Information on biomass characteristics feedstock is essential for scaling-up gasification from the laboratory to industrial-scale. This review deals with the transformation biogenic residues into a valuable bioenergy carrier like biomethanol as the liquid sunshine based on the combination of modified mature technologies such as gasification with other innovative solutions such as membranes and microchannel reactors. Tar abatement is a critical process in product gas upgrading since tars compromise downstream processes and equipment, for this, membrane technology for upgrading syngas quality is discussed in this paper. Microchannel reactor technology with the design of state-of-the-art multifunctional catalysts provides a path to develop decentralised biomethanol synthesis from biogenic residues. Finally, the development of a process chain for the production of (i) methanol as an intermediate energy carrier, (ii) electricity and (iii) heat for decentralised applications based on biomass feedstock flexible gasification, gas upgrading and methanol synthesis is analysed.

Micro-Grid Oil Palm Plantation Waste Gasification Power Plant in Indonesia: Techno-Economic and Socio-Environmental Analysis

The utilization of new and renewable energy sources explicitly based on biomass needs to be increased to reduce dependence on fossil fuels. One of the potential biomasses of plantation waste in Indonesia that can be utilized is oil palm plantation waste in the form of fronds and trunks that are converted with multi-stage downdraft gasification technology. This study aimed to conduct a technical analysis, economic analysis, investment risk analysis, social analysis, and an environmental impact assessment of power plants fueled by oil palm plantation waste. The method used was the upscaling of a prototype of a 10 kW power plant to 100 kW. The results showed that it was technically and economically feasible to apply. The economic indicators were a positive NPV of USD 48.846 with an IRR of 9.72% and a B/C ratio of 1.16. The risk analysis predicted a probability of an NPV 49.94% above the base case. The study of the social aspects suggested that the construction of power plants has a positive impact in the form of increased community income and the growth of new economic sectors that utilize electricity as a primary source. An analysis of the environmental effects is critical so that the impacts can be minimized. Overall, the construction of small-scale power plants in oil palm plantations is worth considering as long as it is carried out following the applicable regulations.

Charcoal production from waste pequi seeds for heat and power generation

Many specialized technologies are available to convert waste biomass into secondary products that have a higher value and are more convenient to process than the original feedstock. This study evaluated the potential of waste pequi seeds to produce high-quality charcoal for subsequent gasification into low-tar producer gas for heat engine applications. We focused on the characterization of pequi seeds, the derived charcoal, and the collected bio-oil from slow pyrolysis conversion of the feedstock. Thermodynamic equilibrium calculations were conducted to assess gasification performance of the parent biomass and its charcoal. We also investigated the thermal degradation kinetics of pequi seeds through non-isothermal thermogravimetric analysis. Finally, a two-step energy-extraction analysis was performed for the carbonization of the parent biomass and further utilization of its charcoal in an integrated gasification gas-engine cycle. Slow pyrolysis of pequi seeds (2 °C min^-1, 430 °C) produced up to 40% of high-grade charcoal with 60% fixed carbon, 43% of bio-oil, and 16% of light gases. The overall energy extraction efficiency was estimated as 61%, based on the higher heating value of wet pequi seeds. The investigation confirmed that waste pequi seeds could be considered a promising renewable energy source for combined heat and power generation for the Brazilian agro-food industry.

Revamping downdraft gasifier to minimize clinker formation for high-ash garden waste as feedstock

The conventional downdraft gasifier, when used with garden waste pellets (ash ∼10%) as feedstock, exhibits formation of clinker due to hardening of softened ash, which results in discontinuous flame and intermittent operation. The design and operation protocol of the gasifier was appropriately modified to circumvent this problem. The effects of parameters such as grate movement, equivalence ratio (ER), and ratio of air entering at combustion and drying zones (split ratio) were systematically studied to maximize the lower heating value (LHV) of gas and minimize the amount of clinker. The grate movement of once in 20 min, ER of 0.32, and air split ratio of 0:100 together proved to be the best for garden waste pellets. The producer gas LHV and cold gas efficiency were 3.59 MJ/Nm³ and 62.61%, respectively, and comparable to the producer gas obtained from other biomass resources such as rice husk, wheat straw, and cotton stalks.

Thermodynamic Model for Updraft Gasifier with External Recirculation of Pyrolysis Gas

Most of the thermodynamic modeling of gasification for updraft gasifier uses one process of decomposition (decomposition of fuel). In the present study, a thermodynamic model which uses two processes of decomposition (decomposition of fuel and char) is used. The model is implemented in modification of updraft gasifier with external recirculation of pyrolysis gas to the combustion zone and the gas flowing out from the side stream (reduction zone) in the updraft gasifier. The goal of the model obtains the influences of amount of recirculation pyrolysis gas fraction to combustion zone on combustible gas and tar. The significant results of modification updraft are that the increases amount of recirculation of pyrolysis gas will increase the composition of H2and reduce the composition of tar; then the composition of CO and CH4is dependent on equivalence ratio. The results of the model for combustible gas composition are compared with previous study.