Search

Crop residues could provide a local, sustainable, and low-cost solid fuel alternative to woody biomass for heat supply in the agricultural community. However, utilization of crop residues on a small scale is associated with increased pollutant emissions, as well as ash-related operational problems. There is ongoing research on fuel conditioning measures, such as fuel leaching, fuel blending, and using mineral additives, as a manner to mitigate these issues. The purpose of this study is to investigate the applicability of additives in the combustion of crop residues under everyday conditions. To this end, wheat straw pellets were combusted in a 30 kW boiler with and without additives (kaolinite and MgO, 2 wt. % and 4 wt. %). Carbon monoxide (CO) and particulate matter (PM) emissions have been monitored during combustion experiments, as well as changes in bottom ash behavior and composition. The results have shown that additives slightly decrease the heating value of the fuel (3%–6%). During experiments with additized wheat straw pellets, higher emissions of CO were observed. Combustion of pure not additized wheat straw pellets resulted in a PM emission of 568 mg/Nm3, which decreased with additives. Both researched additives increase the four characteristic ash deformation temperatures. [ABSTRACT FROM AUTHOR]

Combustion of wheat straw was investigated in a fixed-bed reactor for two air flow rates, 1,151 and 2,125 kg/m2h. Measured temperatures, mass loss, and gas composition were used to evaluate the combustion characteristics in terms of ignition front speed, burning rate, and quality of combustion in general. At lower value of air flow rate difference between the ignition rate and burning rate was significant, which can be easily noticed by the measurement results. At higher value of air flow rate, there was still a small difference between the ignition and burning rate, while the content of oxygen in the flue gas was 10%, which leads to the conclusion that a change in the method of delivering the combustion air is necessary. [ABSTRACT FROM PUBLISHER]

Geothermal heat pumps have several advantages over conventional heating and cooling systems. They can operate in both winter and summer, have high efficiencies, and do not directly emit any greenhouse gases during operation. Investors (in developing countries) can use Clean Development Mechanism as a source of financing for new or existing renewable energy facilities by selling Certified Emission Reductions credits (CERs), which represent the amount of CO2 emission (1 CER¼1 tCO2eq) that is avoided using renewable energy. The aim of this paper is to analyze the possibility of CO2 reduction by using geothermal heat pumps for fossil fuel displacement with applying Clean Development Mechanism. Results have shown that by using geothermal heat pumps during a 7-year crediting period, the estimated emission reduction would be 79.45 tCO2 (equal to 80 CERs), enabling the investor to achieve profit from selling 80 CERs and thus helping to fund the proposed project activity. Three main factors which influence the amount of CO2 reduction have been identified: carbon-dioxide emission factor for electricity source, efficiency of technology used for baseline scenario, and coefficient of performance (COP) of heat pumps. [ABSTRACT FROM AUTHOR]