Orientador: George de Paula Bernardes / Banca: Tácio Mauro Pereira de Campos / Banca: Anna Silvia Palcheco Peixoto / Resumo: A cobertura final de um aterro de resíduos se dá quando a última célula alcança sua cota mais alta. Os principais objetivos da cobertura final em aterros são: minimizar a infiltração de água de chuva, limitar a emissão descontrolada de gases proveniente da decomposição dos resíduos, suprimir a proliferação de vetores, fornecer uma superfície adequada para a revegetação e servir como o elemento central na recuperação do local. Esta pesquisa tem o propósito de analisar as características geotécnicas (mecânicas e hidráulicas) de um solo residual maduro de biotita gnaisse compactado como vermiculita expandida verificando a aplicabilidade desta mistura para construção de cobertura de aterros de resíduos. A vermiculita é um material inodoro, não abrasivo e não carcinogênico e suas propriedades de superfície, em especial a porosidade e carga superficial negativa, promovem a esta material alto poder de absorvente e carreador de nutrientes. Incialmente foram realizados ensaios de absorção de água e de secagem ao ar em amostras compactadas com diferentes porcentagens em volume de vermiculita acrescentada ao solo. Os resultados preliminares mostraram que a relação vermiculita/solo na razão de 40% em volume de solo compactado apresentou um melhor resultado para os testes realizados. A absorção de água atingiu 51% quando comparada ao solo natural (14%) e com relação à perda de massa esta mesma mistura apresentou uma estabilidade de 72 horas a umidade absorvida enquanto o solo natural após 24 horas de secagem ao ar a umidade inicial já havia sico alcançada. Também foram realizados ensaios complementares tais como curva característica, ensaio de compressão diametral e compressão simples, compressibilidade e adensamento, resistência ao cisalhamento direto, permeabilidade e ensaio de formação de trinca... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The final cover for a landfill of waste occurs when the last cell reaches its highest elevation, and he main objectives of this cover are: to minimize infiltration of rainwater, to limit the uncontrolled emission of gases of gases from the decomposition of waste, to suppress the proliferation of vectors, to provide a suitable surface for revegetation and serving as the central element in the recovery site. This study aims to analyze the geotechnical characteristics (mechanical and hydraulic) of soil residual biotite gneiss mature compacted with expanded vermiculite and to verify the applicability of this mixture for construction in waste landfill cover. Vermiculite is a odorless, non-abrasive, non-carcinogenic material, in addition their surface properties, in particular the porosoty and surface charge negative, make this material a high power of absorving and nutrient carrier. Initially, were performed tests by water absorption and drying compressed air in samples with different percentages by volume of vermiculite added to the soil. Preliminary results showed that the vermiculite/soil ratio of 40% by volume of compacted soil was better for the tests. The water absorption reached a value of 51% compared to the natural soil (14%) and with about the mass loss, that same mixture showed a stability of 72 hours of the absorved moisture while the natural soil, after 24 hours by drying the initial moisture content had already been achieved. Then, were conducted additional tests such as the characteristic curve, diametral compreension test, simply compressive compressibility and density, direct shear strength, permeability and formation tests crack. Considering the results presented, the use of expanded vermicule to the soil compacted presents itself as a alternative for a final landfill of waste cover / Mestre

Orientador: Manuel Baldomero Rolando Berrios Godoy / Banca: Andreia Medinilha Pancher / Banca: Diego Correa Maia / Banca: Rafael Alves Orsi / Banca: Marcio José Celeri / Resumo: A presente tese aborda o processo de desenvolvimento socioeconômico e cultural da sociedade contemporânea e, consequentemente, o expressivo crescimento dos centros urbanos e do consumo per capita de bens e serviços, que tem gerado uma maior quantidade de resíduos sólidos, originando diferentes impactos sobre o meio ambiente. Essas mudanças ocasionadas pela ação antrópica têm produzido marcas indeléveis nos registros geológicos do planeta, através do acúmulo de sedimentos e resíduos depositados em diferentes partes, de forma mais rápida do que ocorreria naturalmente. Os resíduos sólidos têm sido constantemente um problema para as gestões municipais, que necessitam planejar estratégias visando a não geração, reutilização e reciclagem de materiais, além da adequação municipal às exigências legais em relação à disposição final dos resíduos, que ocorrem em grande medida, de forma clandestina em lixões, gerando sérios impactos ambientais, econômicos, sociais e de saúde pública. O planejamento na área de resíduos sólidos tem sido cada vez mais complicado para os gestores municipais, pois não se dispõe de recursos financeiros e humanos para realização de planos de gestão que efetivamente direcionem para uma mudança do quadro negativo do setor de resíduos. Esta pesquisa se propôs a entender a elaboração, implementação e avaliação dos planos de gestão integrada de resíduos na Região Centro Sul do Ceará, utilizando o método indutivo para correlacionar o planejamento à efetivação de prog... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The following thesis deal with the socioeconomic and cultural process of development in the contemporary society and, consequently, it deals with the evident growing of town centers, as the 'per capita' consumption of goods and services have been generating more and more wastes, causing a significant impact to the environment. This alteration, which is caused by anthropic acting, have been producing indelible consequences in the geological registers of the planet through the sediment gathering and deposited wastes in different parts in a faster way than it would be naturally. The wastes are a permanent problem to the municipal administration, which needs to create strategies aiming stop the generating, the reusing and the recycling of materials. Moreover, there is also the municipal adequacy to the law requirements in what regards to the waste disposal, that is broadly and undercovered done in landfills, creating serious environmental, economic, social and of public health impacts. The planning on the area of wastes is becoming more and more difficult to the municipal administers, due to the lack of financial and human resources to accomplish the reversion of the negative situation on the wastes sector. This search aims the understanding of the elaboration, implementation and evaluation of the integrated administrative of wastes in the south-center region of Ceará, using the inductive method to correlate the planning to the materialization of programs, projects and actions, a... (Complete abstract click electronic access below) / Doutor

Polímeros oriundos de fontes não renováveis são amplamente utilizados na produção de embalagens e para uso na agricultura, em confecção de estufas, sacos para produção de mudas e filmes para cobertura de solo. Estes plásticos são resistentes à degradação e após utilização passam a ser um problema ambiental, portanto, o desenvolvimento de materiais biodegradáveis é uma necessidade, visto que são produzidos de fontes renováveis e decompõem-se rapidamente, diminuindo o impacto sobre o meio ambiente. O reaproveitamento total ou parcial de resíduos perigosos, como os de couro curtido ao cromo III, também tem sido alvo de pesquisas por gerar um ganho ambiental se comparado a disposição em aterros indunstriais para resíduos perigosos. Dentro deste contexto, no presente trabalho foram produzidos filmes de gelatina comercial e filmes de gelatina extraída de resíduo de couro curtido ao cromo III, em associação a plastificante e enzima transglutaminase (TGase) como agente reticulante. A enzima TGase foi estatisticamente significativa nas propriedades de solubilidade, ângulo de contato e elongação dos filmes produzidos com gelatina comercial. Para os filmes produzidos com gelatina extraída de resíduo de couro curtido ao cromo III, a enzima TGase atuou de forma estatisticamente significativa nas propriedades de solubilidade, umidade, ângulo de contato, permeabilidade ao vapor d água e tensão de ruptura dos filmes. As análises térmicas mostraram que a reticulação enzimática aumentou a estabilidade térmica dos filmes. A análise de infravermelho evidenciou a reticluação da enzima transglutaminase nos filmes pelo deslocamento das bandas. No teste de biodegradabilidade em solo simulado, os filmes degradaram-se em 24 horas, comprovando que o polímero é biodegradável. Este estudo demonstrou a viabilidade da utilização de gelatina recuperada de um resíduo para produzir filmes biodegradáveis com melhorias na suas propriedades com adição de um agente reticulante. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES. / Polymers from non-renewable sources are widely used in the production of packaging and for use in agriculture, in the manufacture of greenhouses, bags for the production of seedlings and films for soil cover. These plastics are resistant to degradation and after use become an environmental problem, therefore, the development of biodegradable materials is a necessity, since they are produced from renewable sources and decompose rapidly, reducing the impact on the environment. The total or partial reuse of hazardous wastes, such as chrome-tanned leather III, has also been the subject of research for generating an environmental gain compared to disposal in industrial landfills for hazardous waste. In this context, commercial gelatin films and gelatin films extracted from leather residue to chromium III, in combination with plasticizer and enzyme transglutaminase (TGase) as crosslinking agent were produced in the present work. The enzyme TGase was statistically significant in the properties of solubility, contact angle and elongation of the films produced with commercial gelatin. For the films produced with gelatine extracted from chromium III tanned leather residue, the enzyme TGase was statistically significant in the properties of solubility, humidity, contact angle, water vapor permeability and rupture stress of the films. Thermal analysis showed that enzymatic crosslinking increased the thermal stability of films. Infrared analysis evidenced the reticulation of the transglutaminase enzyme in the films by the bands displacement. In the biodegradability test in simulated soil, the films degraded in 24 hours, proving that the polymer is biodegradable. This study demonstrated the feasibility of using gelatine recovered from a residue to produce biodegradable films with improvements in its properties with the addition of a crosslinking agent.

Os materiais poliméricos são vastamente utilizados em várias áreas de aplicação, como na construção civil, automobilística, embalagens, indústrias em geral, entre outras, substituindo de modo versátil e eficiente os metais, cerâmicos e madeira. No entanto, existe um grande volume de descarte de resíduos industriais poliméricos que atualmente não recebem destinação adequada para reciclagem, entre eles o poliuretano (PU) termorrígido (espumas rígidas e flexíveis). O PU é um material versátil devido a sua vasta possibilidade de aplicações, porém grandes volumes de PU na forma de resíduos industriais e materiais de pós-uso são descartados em aterros industriais e sanitários todos os anos. O reaproveitamento dos resíduos de PU pelo processo de reciclagem mecânica é uma alternativa ambientalmente sustentável e correta, pois gera valor agregado a este material e promove uma melhor utilização dos recursos naturais não renováveis. O objetivo deste trabalho foi o desenvolvimento de placas aglomeradas de resíduos industriais de poliuretano skin (PUs) com a adição de diferentes retardantes de chama, além da avaliação das propriedades de reação ao fogo, morfológicas, físicas e mecânicas dos aglomerados obtidos. As composições utilizadas foram 40 a 70 % (massa) de resíduos industriais de PUs, 30 % de agente aglomerante (Elastan) e 0 a 30 % de diferentes retardantes de chama (alumina trihidratada - ATH, polifosfato de melamina - MPP, polifosfato de amônio - APP e trióxido de antimônio + óxido de decabromodifenila - TADB ). Para obtenção das placas aglomeradas, diferentes composições foram moldadas por compressão utilizando 2 a 6 kgf·cm-2 a 60 ºC por 10 min. Este estudo concluiu que as amostras PUs(40)/APP(30) e PUs(40)/TADB(30) (contendo 30 % (massa) de retardantes de chama) apresentaram os melhores resultados de reação ao fogo, com classificação V0 conforme a norma UL94-V. Foi evidenciado também que diferentes tamanhos de granulometrias de PUs não alteraram as propriedades de comportamento ao fogo dos aglomerados desenvolvidos. Os ensaios mecânicos mostraram que os aglomerados possuem resistência superior à necessária para o manuseio e aplicação dos mesmos, e os resultados de condutividade térmica mostraram que estes materiais possivelmente podem ser destinados para aplicações térmicas na construção civil e na indústria. / The polymeric materials are widely used in many application areas, such as in civil construction, automotive, packaging, general industry, among others, replacing metals, ceramics and wood in a versatile and efficient way However, there is a large volume of discard of polymeric industrial waste that does not currently receive adequate destination for recycling, among them thermo-rigid polyurethane (PU) (rigid and flexible foams). The polyurethane (PU) is a versatile material because of its wide range of applications, but large volumes of PU in the form of industrial waste and post-use materials are disposed of in industrial and sanitary landfills every year. The reuse of PU waste by the mechanical recycling process is an environmentally sustainable and correct alternative, as it generates added value to this material and promotes a better use of non-renewable natural resources. The objective of this work was the development of agglomerated boards of skin polyurethane (PUs) (industrial wast) with the addition of different flame retardants, as well as the evaluation of fire reaction, morphological, physical and mechanical properties of the agglomerates obtained. The compositions used were 40 to 70 % (mass) industrial waste PUs, 30 % binder agent (Elastan) and 0 to 30 % of different flame retardants (alumina trihydrate - ATH, melamine polyphosphate - MPP, ammonium polyphosphate - APP and antimony trioxide + decabromodiphenyl oxide - TADB). To obtain the agglomerated boards, different compositions were compression molded using 2 to 6 kgf·cm-2 at 60 °C for 10 min. This study concluded that the samples PUs(40)/APP(30) and PUs(40)/TADB(30) (containing 30 % by mass of flame retardants) presented the best results of reaction to fire, with classification V0, according to the UL94-V standard. It was also evidenced that different size of PU granulometry does not alter the properties of reaction to fire of the developed agglomerates. The mechanical tests show that the agglomerates have superior resistance than necessary for the handling and application, and the results of thermal conductivity prove that these materials can possibly be destined for thermic applications in building construction and industry.

Hog fuel is increasingly becoming an alternative to alleviate the energy problems associated with the use of fossil fuels. To make adequate use of hog fuel, its moisture content should be reduced prior to combustion either in an external dryer or in the initial stages of a hog fuel boiler. Therefore, this research project was undertaken to establish the factors which govern the drying rate of wet hog fuel particles. The convective drying of wood-waste on the slow moving bed of hog fuel boilers was simulated in a packed bed. The information which was obtained can also be applied to approximate the drying behaviour in external dryers. An apparatus was constructed to accommodate the use of hot air, flue gas, superheated steam and a mixture of them as drying media. Drying tests were carried out, over the temperature range of 125-245°C, on 1.1 to 4 kg batches of Western Hemlock hog fuel of thicknesses from 2 to 12 mm. The relative effects of velocity (V), temperature (T), nature of the drying gas, bed depth (L), and initial moisture content of the hog fuel samples (M₀) on the drying process were investigated using a mixture of several thickness fractions having an average (sauter mean) particle thickness (dp) of 6.3 mm. Drying rates were determined through measurement of the change either in humidity of the drying gas, or flow rate of the superheated steam across the bed of hog fuel. Gas humidity was measured using an optical dew point sensor and steam flow was monitored using an orifice plate connected to a massflow transmitter. Drying rates have been quantified as functions of hog fuel particle thickness, initial moisture content and bed depth. The effects of gas temperature, velocity and humidity have also been quantitatively established. The drying process was insensitive to CO₂ content of the drying gas. The existence of an inversion temperature above which drying rates increase with humidity of the drying medium was both experimentally and theoretically confirmed and the locus of inversion points was determined. Instantaneous normalized drying rates, ƒ, and characteristic moisture contents, Φ , have been determined and the existence of a unified characteristic drying rate curve was verified. Using a receding plane model, ƒ was formulated as a function of Φ, for dp = 6.3 mm and at L = 25 cm, for both superheated steam and relatively dry air. Pressure drop measurements were obtained for all the runs with the exception of the superheated steam ones. Application of an accepted pressure drop equation permitted the sphericity of the hog fuel particles to be approximated. A design equation for gas pressure drop in beds of hog fuel particles was investigated. The simultaneous heat and mass transfer processes in drying during the heat transfer controlled period was studied. Using the concept of volumetric evaporation, an empirical correlation for the overall heat transfer coefficient in a packed bed of hog fuel particles has been obtained. The effects of different parameters on both the particle residence time required for drying and the grate heat release rate in hog fuel boilers were determined. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The scarcity of feed resources often imposes a major challenge to the development of animal production in the tropics and subtropics. However, by-products have long been recognised in providing cheaper alternative feed ingredients relative to conventional feed ingredients, thus alleviating the challenge. The aim of the present study was to investigate the potential of three waste products from the subtropical fruit processing industry in animal feeding. The products include avocado meal (AM), macadamia oil cake (MOC) and macadamia chips (MCH). The samples were obtained from the processing plants in Nelspruit of Mpumalanga Province, Makhado (Louis Trichardt) and Tzaneen of Limpompo Province. Eight samples of each waste product were collected, prepared and their chemical composition, in vitro dry matter digestibility and, in situ ruminal dry matter and crude protein (CP) degradability were determined. A broiler growth trial was conducted as well to determine the effect of replacing maize with AM on performance of broilers under commercial production thus establishing the replacement value of avocado meal in broiler feeds. As the products under study were from the oil extraction process of the two fruits, there were high remnants of oil in all three waste products. As a result the ether extract (EE) content of the three waste products was higher compared to any of the commonly used oilseed meals. The MCH had the highest EE concentration, followed by the MOC and the AM had the lowest. However, after defatting the AM had the highest (P<0.05) EE concentration compared to either the MOC or MCH. The CP concentration of the MOC was significantly higher than that of the AM and MCH. There was no significant difference observed between the AM and MCH in CP concentration. A better amino acid profile was observed with the MOC compared to the AM and MCH. None of the products can be regarded as a protein source. The fibre fractions of the MCH were significantly higher than that of AM and MOC, with the exception of the acid detergent lignin (ADL) concentration. The ADL concentration of the AM and MCH did not differ significantly although the MCH concentration was higher. The MOC had the lowest (P<0.05) ADL concentration compared among these waste products. Generally, the fibre concentration in the MOC was lower compared to other waste products but higher compared to the SBM and POCM. The acid detergent insoluble nitrogen (ADIN) concentration of the AM was significantly higher than that of MOC and MCH. There was no significant difference observed between MOC and MCH. The condensed tannin (CT) concentration of the waste products differed significantly with the AM being the highest and the MOC the lowest. The ADIN concentration of the MOC could be compared to that of the SBM and lower than that of the POCM. There were some significant differences observed in the mineral composition between the waste products under study. The mineral concentrations were below the maximum tolerable levels of animals except for iron (Fe) in AM which can be toxic to sheep as it was above the maximum tolerable level of 500mg/kg. The in vitro dry matter digestibility of the three waste products differed significantly, with the MOC being the highest and the MCH the lowest. Huge variation within waste products was observed and it could be due to the contamination levels of the products with the indigestible portions of the parent fruits. The in situ degradability of dry matter and CP of the AM and MOC differed significantly, with the MOC surpassing the AM in most of the degradability characteristics. The potential degradable fraction (“b”) and the degradation rate of the b fraction (“c”) fractions of the AM and MOC did not differ significantly. The MCH had more indigestible particles of the kernel and as a result it could not be analysed statistically and was therefore omitted. The effect of replacing maize with AM at different inclusion rates led to decreased feed intake and the final mass of the broilers during the trial period. The feed intake of the broilers on commercial diet was significantly higher than that of the broilers on commercial diets with avocado meal, except for the inclusion rate of 10% AM. The final mass, the ADG and the FCE of the broilers on commercial diet were significantly higher compared to the broilers on diet with AM irrespective of the inclusion rate. No mortalities observed during the experimental period. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

Orientador: Robert Boyd Harrison / Coorientador: Iraê Amaral Guerrini / Banca: Roberto Lyra Villas Bôas / Banca: Vera Lucia Mores Rall / Banca: Cássio Hamilton Abreu Junior / Banca: Fernando Carvalho Oliveira / Resumo: No Brasil, a maior parte do lodo de esgoto sanitário gerado nas Estações de Tratamento de Esgoto é destinada a aterros sanitários, o que preocupa técnicos e autoridades, que buscam alternativas de destinação mais adequadas ao meio ambiente. O processo de compostagem permite a estabilização e a higienização do lodo de esgoto, que pode então ser aplicado em solos agrícolas, aproveitando a matéria orgânica e os nutrientes ali presentes. O objetivo principal deste trabalho foi estudar de forma detalhada o comportamento dos indicadores de patogenicidade Salmonella spp., coliformes termotolerantes e ovos viáveis de Ascaris spp. em função da temperatura e da umidade durante o processo de compostagem de lodo de esgoto com diferentes materiais estruturantes, verificando se o processo é eficaz na higienização do material. Para isto, o estudo foi dividido em quatro experimentos. No Experimento 1, sensores de temperatura foram instalados em três diferentes perfis da pilha de compostagem (topo, meio e base) e verificou-se que a mistura de lodo de esgoto com bagaço de cana-de-açúcar apresentou temperaturas mais uniformes nos três perfis, a mistura com casca de eucalipto apresentou as temperaturas mais elevadas no topo e no meio da pilha e a mistura com casca de arroz apresentou baixas temperaturas em todos os perfis, sendo, então, considerada uma mistura inadequada para compostagem. O Experimento 2 avaliou dois métodos para determinação do número de ovos viáveis de Ascaris spp. em amostras... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In Brazil, most of the biosolids generated daily by Wastewater Treatment Plants are destined to landfills, which raises a great concern of technicians and authorities, who seek alternatives of destination more appropriate to the environment. The composting allows the stabilization of biosolids, reducing or even eliminating the load of pathogenicity indicators present in it, which can then be applied to agricultural soils, taking advantage of its organic matter and nutrients. The main objective of this work was to study in detail the behavior of the pathogenicity indicators Salmonella spp., thermotolerant coliforms and Ascaris spp. viable ova as a function of temperature and moisture during the biosolids composting with different structuring materials, verifying if the process is effective in sanitizing the material. Therefore, the study was divided into four experiments. In Experiment 1, temperature sensors were installed in three different profiles of the compost pile (top, middle and bottom) and it was verified that the mixture of biosolids with sugarcane bagasse presented more uniform temperatures in the three profiles, the mixture with Eucalyptus bark showed the highest temperatures at the top and middle of the pile and the mixture with rice husk showed low temperatures in all the profiles, being considered an inadequate mixture for composting. Experiment 2 evaluated two methods for determining the number of viable ova of Ascaris spp. in biosolids samples, the USEPA method and the Norma Mexicana method, and the USEPA method was considered the most efficient in determining the number of viable ova of Ascaris spp. in the biosolids samples analyzed. Experiment 3 evaluated throughout the composting process the presence of Salmonella spp. and the decay of thermotolerant coliforms and viable ova of Ascaris spp. The presence of Salmonella spp. was verified in only one occurrence for each mixture ... / Doutor

The process wastewater from three blue crab processing plants in Virginia was characterized. Most of these effluent streams were highly concentrated. For example, the retort water from the cookers exhibited the following concentrations: BOD₅ = 14,000-29,000 mg/L, TSS = 650-6,200 mg/L, TKN-N = 2,500-4,000 mg/L, NH3-N = 70-160 mg/L and Total Phosphorus= 100-185 mg/L. One process effluent contained chloride concentrations exceeding 100,000 mg/L. Analysis of production and effluent characterization data from two mechanized plants revealed that wastewater volumes and concentrations varied significantly between the two plants. Both plants exhibited highly variable daily and seasonal production. Treatability studies were completed on the process wastewater because discharge limits exist for TSS, Oil and Grease and in some cases BODs and ammonia. Settling and filtration studies were performed on these effluents. The organics and nutrients in the wastes were highly soluble and limited reduction of COD (18-65% reduction), BOD₅ (9-49% reduction), TKN-N (9-62% reduction), and TP (10-66%) was achieved by filtration. Acidification of the concentrated effluents caused some coagulation of the contents. Coagulation by pH adjustment was most effective between pH 3.0-4.0. TSS removals of 76- 93%, and BOD5 removals of 6-30% were achieved by pH adjustment, thereby showing promise as a pretreatment method. Anaerobic biological treatment systems appear promising for the treatment of wastewater from blue crab processing plants (effluent BOD₅s ranged from 150-420 mg/L), especially for cooker effluent. However, there is concern that salt from the Harris Claw operation will decrease anaerobic treatment performance and that effluent NH3 and TSS levels will need to be further reduced to meet permit limits. Pretreatment of process wastewater by means of pH adjustment did not improve anaerobic treatability. / Master of Science

No description available.

The economic feasibility and energy effectiveness of producing pipeline quality methane gas from biomass was assessed for a new and totally unproven process. The biomass feedstock considered was the common aquatic weed water hyacinth and a novel active boom-winch harvesting system is proposed for its collection. The conversion process analyzed is a two stage biological process which utilizes a leaching-bed for the production of volatile acids and a packed-bed for the production of methane gas. In order to determine the feasibility of the proposed process equipment requirements, capital costs and operating/maintenance costs were developed for three system sizes. This data was analyzed using a life cycle cost model to determine pay back period. The results indicate that payoff period will be less than equipment life and that net energy production occurs. Areas where further research would promote the introduction of this technology are identified and discussed.