Crop residues on short-term CO2 emissions in sugarcane production areas

The proper management of agricultural crop residues could produce benefits in a warmer, more drought-prone world. Field experiments were conducted in sugarcane production areas in the Southern Brazil to assess the influence of crop residues on the soil surface in short-term CO2 emissions. The study was carried out over a period of 50 days after establishing 6 plots with and without crop residues applied to the soil surface. The effects of sugarcane residues on CO2 emissions were immediate; the emissions from residue-covered plots with equivalent densities of 3 (D50) and 6 (D100) t ha-1 (dry mass) were less than those from non-covered plots (D0). Additionally, the covered fields had lower soil temperatures and higher soil moisture for most of the studied days, especially during the periods of drought. Total emissions were as high as 553.62 ± 47.20 g CO2 m-2, and as low as 384.69 ± 31.69 g CO2 m-2 in non-covered (D0) and covered plot with an equivalent density of 3 t ha-1 (D50), respectively. Our results indicate a significant reduction in CO2 emissions, indicating conservation of soil carbon over the short-term period following the application of sugarcane residues to the soil surface.

Control of ammonia emissions in naturally ventilated dairy cattle facilities in Portugal

We conducted a study of the processes associated to NH3 emission in naturally ventilated dairy cattle facilities, having described factors that regulate NH3 emission, as well as methodologies for measuring these emissions at these facilities. Appropriate techniques to mitigate NH3 emission in facilities located in regions with warm climates were also identified. The most effective mitigation techniques with simple implementation include strategies associated to: (i) installation design and flooring, which lead to reduced emissions, (ii) excreta pre-excretion, namely the use of diets with optimized crude protein content and increased milk production at farm level; and (iii) excreta post-excretion, particularly by changing the conditions of environmental monitoring within the premises, practice introduction or additive application in the management of excreta deposited on floors.

The effects of location, feedstock availability, and supply-chain logistics on the greenhouse gas emissions of forest-biomass energy utilization in Finland

Forest biomass represents a geographically distributed feedstock, and geographical location affects the greenhouse gas (GHG) performance of a given forest-bioenergy system in several ways. For example, biomass availability, forest operations, transportation possibilities and the distances involved, biomass end-use possibilities, fossil reference systems, and forest carbon balances all depend to some extent on location. The overall objective of this thesis was to assess the GHG emissions derived from supply and energy-utilization chains of forest biomass in Finland, with a specific focus on the effect of location in relation to forest biomass’s availability and the transportation possibilities. Biomass availability and transportation-network assessments were conducted through utilization of geographical information system methods, and the GHG emissions were assessed by means of lifecycle assessment. The thesis is based on four papers in which forest biomass supply on industrial scale was assessed. The feedstocks assessed in this thesis include harvesting residues, smalldiameter energy wood and stumps. The principal implication of the findings in this thesis is that in Finland, the location and availability of biomass in the proximity of a given energyutilization or energy-conversion plant is not a decisive factor in supply-chain GHG emissions or the possible GHG savings to be achieved with forest-biomass energy use. Therefore, for the greatest GHG reductions with limited forest-biomass resources, energy utilization of forest biomass in Finland should be directed to the locations where most GHG savings are achieved through replacement of fossil fuels. Furthermore, one should prioritize the types of forest biomass with the lowest direct supply-chain GHG emissions (e.g., from transport and comminution) and the lowest indirect ones (in particular, soil carbon-stock losses), regardless of location. In this respect, the best combination is to use harvesting residues in combined heat and power production, replacing peat or coal.

Sorbent characterization for circulating fluidized bed scrubbers

Harmful sulfur dioxide (SO2) emissions from power plants have increasingly been restricted since the 1970’s. Circulating fluidized bed (CFB) scrubber is a dry flue gas desulfurization method of absorbing SO2 out of the flue gas with sorbent. In current commercial plants, the used sorbent is commercial or on-site hydrated calcium hydroxide. The CFB scrubber process is characterized by a close but adequate approach to the flue gas saturation temperature that is achieved by spraying water to the absorber followed by a particulate control device. Very high SO2 removal is achieved along with a dry byproduct that is continuously recirculated back to the absorber for enhanced sorbent utilization. The aim of this work is to develop a method that would characterize the reactivity of sorbents used in CFB scrubbers and to conclude how different process parameters and sorbent properties affect the sulfur absorption. The developed characterization method is based on a fixed bed of sorbent and inert silica sand, through which an SO2 containing gas mixture is led. The reaction occurs in the bed and the SO2 concentration in the outlet as a function of time, a breakthrough curve, is obtained from the analyzer. Reactivity of the sorbents are evaluated by the absorbed sulfur amount. Results suggest that out of process parameters, lower SO2 concentration, lower temperature and higher moisture content enhance the desulfurization. Between different sorbents, specific surface area seems to be the most significant parameter. Large surface area linearly leads to more efficient desulfurization. Overall, the solid conversion levels in the tests were very low creating uncertainty to the validity of the results. New desing is being planned to overcome the problems of the device.

Greenhouse gas emissions from peat and biomass-derived fuels, electricity and heat — Estimation of various production chains by using LCA methodology

More discussion is required on how and which types of biomass should be used to achieve a significant reduction in the carbon load released into the atmosphere in the short term. The energy sector is one of the largest greenhouse gas (GHG) emitters and thus its role in climate change mitigation is important. Replacing fossil fuels with biomass has been a simple way to reduce carbon emissions because the carbon bonded to biomass is considered as carbon neutral. With this in mind, this thesis has the following objectives: (1) to study the significance of the different GHG emission sources related to energy production from peat and biomass, (2) to explore opportunities to develop more climate friendly biomass energy options and (3) to discuss the importance of biogenic emissions of biomass systems. The discussion on biogenic carbon and other GHG emissions comprises four case studies of which two consider peat utilization, one forest biomass and one cultivated biomasses. Various different biomass types (peat, pine logs and forest residues, palm oil, rapeseed oil and jatropha oil) are used as examples to demonstrate the importance of biogenic carbon to life cycle GHG emissions. The biogenic carbon emissions of biomass are defined as the difference in the carbon stock between the utilization and the non-utilization scenarios of biomass. Forestry-drained peatlands were studied by using the high emission values of the peatland types in question to discuss the emission reduction potential of the peatlands. The results are presented in terms of global warming potential (GWP) values. Based on the results, the climate impact of the peat production can be reduced by selecting high-emission-level peatlands for peat production. The comparison of the two different types of forest biomass in integrated ethanol production in pulp mill shows that the type of forest biomass impacts the biogenic carbon emissions of biofuel production. The assessment of cultivated biomasses demonstrates that several selections made in the production chain significantly affect the GHG emissions of biofuels. The emissions caused by biofuel can exceed the emissions from fossil-based fuels in the short term if biomass is in part consumed in the process itself and does not end up in the final product. Including biogenic carbon and other land use carbon emissions into the carbon footprint calculations of biofuel reveals the importance of the time frame and of the efficiency of biomass carbon content utilization. As regards the climate impact of biomass energy use, the net impact on carbon stocks (in organic matter of soils and biomass), compared to the impact of the replaced energy source, is the key issue. Promoting renewable biomass regardless of biogenic GHG emissions can increase GHG emissions in the short term and also possibly in the long term.

Mitigation possibilities to Greenhouse gas emissions from power production in India

Global warming is assertively the greatest environmental challenge for humans of 21st century. It is primarily caused by the anthropogenic greenhouse gas (GHG) that trap heat in the atmosphere. Because of which, the GHG emission mitigation, globally, is a critical issue in the political agenda of all high-profile nations. India, like other developing countries, is facing this threat of climate change while dealing with the challenge of sustaining its rapid economic growth. India’s economy is closely connected to its natural resource base and climate sensitive sectors like water, agriculture and forestry. Due to Climate change the quality and distribution of India’s natural resources may transform and lead to adverse effects on livelihood of its people. Therefore, India is expected to face a major threat due to the projected climate change. This study proposes possible solutions for GHG emission mitigation that are specific to the power sector of India. The methods discussed here will take Indian power sector from present coal dominant ideology to a system, centered with renewable energy sources. The study further proposes a future scenario for 2050, based on the present Indian government policies and global energy technologies advancements.

Application of cerium oxide thin films grown by atomic layer deposition for soot removal

The objective of the thesis is to study cerium oxide thin films grown by the atomic layer deposition (ALD) for soot removal. Cerium oxide is one of the most important heterogeneous catalysts and can be used in particulate filters and sensors in a diesel exhaust pipe. Its redox/oxidation properties are a key factor in soot oxidation. Thus, the cerium oxide coating can help to keep particulate filters and sensors clean permanently. The literature part of the thesis focuses on the soot removal, introducing the origin and structure of soot, reviewing emissions standards for diesel particulate matter, and presenting methods and catalysts for soot removal. In the experimental part the optimal ALD conditions for cerium oxide were found, the structural properties of cerium oxide thin films were analyzed, and the catalytic activity of the cerium oxide for soot oxidation was investigated. Studying ALD growth conditions of cerium oxide films and determining their critical thickness range are important to maximize the catalytic performance operating at comparatively low temperature. It was found that the cerium oxide film deposited at 300 °C with 2000 ALD cycles had the highest catalytic activity. Although the activity was still moderate and did not decrease the soot oxidation temperature enough for a real-life application. The cerium oxide thin film deposited at 300 °C has a different crystal structure, surface morphology and elemental composition with a higher Ce3+ concentration compared to the films deposited at lower temperatures. The different properties of the cerium oxide thin film deposited at 300 °C increase the catalytic activity most likely due to higher surface area and addition of the oxygen vacancies.

Minimizing Conducted RF-Emissions in Switch Mode Power Supplies Using Spread-Spectrum Techniques

Switching power supplies are usually implemented with a control circuitry that uses constant clock frequency turning the power semiconductor switches on and off. A drawback of this customary operating principle is that the switching frequency and harmonic frequencies are present in both the conducted and radiated EMI spectrum of the power converter. Various variable-frequency techniques have been introduced during the last decade to overcome the EMC problem. The main objective of this study was to compare the EMI and steady-state performance of a switch mode power supply with different spread-spectrum/variable-frequency methods. Another goal was to find out suitable tools for the variable-frequency EMI analysis. This thesis can be divided into three main parts: Firstly, some aspects of spectral estimation and measurement are presented. Secondly, selected spread spectrum generation techniques are presented with simulations and background information. Finally, simulations and prototype measurements from the EMC and the steady-state performance are carried out in the last part of this work. Combination of the autocorrelation function, the Welch spectrum estimate and the spectrogram were used as a substitute for ordinary Fourier methods in the EMC analysis. It was also shown that the switching function can be used in preliminary EMC analysis of a SMPS and the spectrum and autocorrelation sequence of a switching function correlates with the final EMI spectrum. This work is based on numerous simulations and measurements made with the prototype. All these simulations and measurements are made with the boost DC/DC converter. Four different variable-frequency modulation techniques in six different configurations were analyzed and the EMI performance was compared to the constant frequency operation. Output voltage and input current waveforms were also analyzed in time domain to see the effect of the spread spectrum operation on these quantities. According to the results presented in this work, spread spectrum modulation can be utilized in power converter for EMI mitigation. The results from steady-state voltage measurements show, that the variable-frequency operation of the SMPS has effect on the voltage ripple, but the ripple measured from the prototype is still acceptable in some applications. Both current and voltage ripple can be controlled with proper main circuit and controller design.

Biogas production in regional integrated biodegradable waste treatment – Possibilities for improving energy performance and reducing GHG emissions

The greatest threat that the biodegradable waste causes on the environment is the methane produced in landfills by the decomposition of this waste. The Landfill Directive (1999/31/EC) aims to reduce the landfilling of biodegradable waste. In Finland, 31% of biodegradable municipal waste ended up into landfills in 2012. The pressure of reducing disposing into landfills is greatly increased by the forthcoming landfill ban on biodegradable waste in Finland. There is a need to discuss the need for increasing the utilization of biodegradable waste in regional renewable energy production to utilize the waste in a way that allows the best possibilities to reduce GHG emissions. The objectives of the thesis are: (1) to find important factors affecting renewable energy recovery possibilities from biodegradable waste, (2) to determine the main factors affecting the GHG balance of biogas production system and how to improve it and (3) to find ways to define energy performance of biogas production systems and what affects it. According to the thesis, the most important factors affecting the regional renewable energy possibilities from biodegradable waste are: the amount of available feedstock, properties of feedstock, selected utilization technologies, demand of energy and material products and the economic situation of utilizing the feedstocks. The biogas production by anaerobic digestion was seen as the main technology for utilizing biodegradable waste in agriculturally dense areas. The main reason for this is that manure was seen as the main feedstock, and it can be best utilized with anaerobic digestion, which can produce renewable energy while maintaining the spreading of nutrients on arable land. Biogas plants should be located close to the heat demand that would be enough to receive the produced heat also in the summer months and located close to the agricultural area where the digestate could be utilized. Another option for biogas use is to upgrade it to biomethane, which would require a location close to the natural gas grid. The most attractive masses for biogas production are municipal and industrial biodegradable waste because of gate fees the plant receives from them can provide over 80% of the income. On the other hand, directing gate fee masses for small-scale biogas plants could make dispersed biogas production more economical. In addition, the combustion of dry agricultural waste such as straw would provide a greater energy amount than utilizing them by anaerobic digestion. The complete energy performance assessment of biogas production system requires the use of more than one system boundary. These can then be used in calculating output–input ratios of biogas production, biogas plant, biogas utilization and biogas production system, which can be used to analyze different parts of the biogas production chain. At the moment, it is difficult to compare different biogas plants since there is a wide variation of definitions for energy performance of biogas production. A more consistent way of analyzing energy performance would allow comparing biogas plants with each other and other recovery systems and finding possible locations for further improvement. Both from the GHG emission balance and energy performance point of view, the energy consumption at the biogas plant was the most significant factor. Renewable energy use to fulfil the parasitic energy demand at the plant would be the most efficient way to reduce the GHG emissions at the plant. The GHG emission reductions could be increased by upgrading biogas to biomethane and displacing natural gas or petrol use in cars when compared to biogas CHP production. The emission reductions from displacing mineral fertilizers with digestate were seen less significant, and the greater N2O emissions from spreading digestate might surpass the emission reductions from displacing mineral fertilizers.

Reduction of nitrogen oxide emissions in lime kiln

Different nitrogen oxide removal technologies for rotary lime kiln are studied in this thesis, the main focus being in commercial technologies. Post-combustion methods are investigated in more detail as potential possible NOx removal with combustion methods in rotary lime kiln is more limited or primary methods are already in use. However, secondary methods as NOx scrubber, SNCR or SCR technologies are not listed as the Best Available Technologies defined by European Union. BAT technologies for NOx removal in lime kiln are (1) Optimised combustion and combustion control, (2) Good mixing of fuel and air, (3) Low-NOx burner and (4) Fuel selection/low-N fuel. SNCR method is the most suitable technique for NOx removal in lime kiln when NOx removal from 50 % to 70 % is required in case primary methods are already in use or cannot be applied. In higher removal cases ammonia slip is an issue in SNCR. By using SCR better NOx reduction can be achieved but issues with catalyst materials are expected to arise because of the dust and sulphur dioxide which leads to catalyst poison formation in lower flue gas temperatures. NOx scrubbing has potential when simultaneous NOx and SO2 removal is required. The challenge is that NO cannot be scrubbed directly, but once it is oxidized to NO2 or further scrubbing can be performed as the solubility of NO2 is higher. Commercial installations have not been made regarding SNCR, SCR or NOx scrubbing regarding rotary lime kiln. For SNCR and SCR the closest references come from cement industry.

The use of protein structure/activity relationships in the rational design of stable particulate delivery systems

The recombinant heat shock protein (18 kDa-hsp) from Mycobacterium leprae was studied as a T-epitope model for vaccine development. We present a structural analysis of the stability of recombinant 18 kDa-hsp during different processing steps. Circular dichroism and ELISA were used to monitor protein structure after thermal stress, lyophilization and chemical modification. We observed that the 18 kDa-hsp is extremely resistant to a wide range of temperatures (60% of activity is retained at 80ºC for 20 min). N-Acylation increased its ordered structure by 4% and decreased its ß-T1 structure by 2%. ELISA demonstrated that the native conformation of the 18 kDa-hsp was preserved after hydrophobic modification by acylation. The recombinant 18 kDa-hsp resists to a wide range of temperatures and chemical modifications without loss of its main characteristic, which is to be a source of T epitopes. This resistance is probably directly related to its lack of organization at the level of tertiary and secondary structures.

Ambient particulate air pollution from vehicles promotes lipid peroxidation and inflammatory responses in rat lung

Oxidative stress plays a major role in the pathogenesis of particle-dependent lung injury. Ambient particle levels from vehicles have not been previously shown to cause oxidative stress to the lungs. The present study was conducted to a) determine whether short-term exposure to ambient levels of particulate air pollution from vehicles elicits inflammatory responses and lipid peroxidation in rat lungs, and b) determine if intermittent short-term exposures (every 4 days) induce some degree of tolerance. Three-month-old male Wistar rats were exposed to ambient particulate matter (PM) from vehicles (N = 30) for 6 or 20 continuous hours, or for intermittent (5 h) periods during 20 h for 4 consecutive days or to filtered air (PM <10 µm; N = 30). Rats continuously breathing polluted air for 20 h (P-20) showed a significant increase in the total number of leukocytes in bronchoalveolar lavage compared to control (C-20: 2.61 x 105 ± 0.51;P-20: 5.01 x 105 ± 0.81; P < 0.05) and in lipid peroxidation ([MDA] nmol/mg protein: C-20: 0.148 ± 0.01; P-20: 0.226 ± 0.02; P < 0.05). Shorter exposure (6 h) and intermittent 5-h exposures over a period of 4 days did not cause significant changes in leukocytes. Lipid damage resulting from 20-h exposure to particulate air pollution did not cause a significant increase in lung water content. These data suggest oxidative stress as one of the mechanisms responsible for the acute adverse respiratory effects of particles, and suggest that short-term inhalation of ambient particulate air pollution from street with high automobile traffic represents a biological hazard.

Climatic changes: what if the global increase of CO2 emissions cannot be kept under control?

Climatic changes threaten the planet. Most articles related to the subject present estimates of the disasters expected to occur, but few have proposed ways to deal with the impending menaces. One such threat is the global warming caused by the continuous increase in CO2 emissions leading to rising ocean levels due to the increasing temperatures of the polar regions. This threat is assumed to eventually cause the death of hundreds of millions of people. We propose to desalinize ocean water as a means to reduce the rise of ocean levels and to use this water for populations that need good quality potable water, precisely in the poorest regions of the planet. Technology is available in many countries to provide desalinated water at a justifiable cost considering the lives threatened both in coastal and desertified areas.