• Energy Research

This research identified the optimal scenarios to produce three bioenergy outputs: dual generation (electricity and heat), electricity, and heat in two regions located in the northern part of Costa Rica. Two biomass conversion technologies—boilers and gasification—with 2, 5, and 10 MW production capacities were assessed to ascertain the most suitable technology-capacity pairing for each bioproduct. To this end, a comprehensive financial model was developed to maximize the net present value. Following this, the equilibrium point for biomass supply and demand was ascertained, alongside estimations of the associated costs and energy utility. The findings indicated that the three bioenergy products could be completed within the local energy market at prices below 0.14 USD/kWh, with maximum supply distances of 90 km. The boiler and turbine technology proved most suitable for dual and electricity generation, with capacities ranging between 2 MW and 5 MW, where differentiation was influenced by biomass transportation. Furthermore, heat generation demonstrated financial viability at a capacity of 2 MW. In the evaluation of supply-demand break-even points, a maximum benefit of 26% was observed, with dual production yielding the highest benefits and heat production being the least favorable option due to the costs linked to biomass transportation and the low efficiency of energy transformation.

ABSTRACT Background: The use of tree plantations for energy purposes has shown an increase in their use in tropical regions due to the species' rapid growth and low cost of energy generation. This has led to the development of optimization studies of crop conditions. However, the determination of the effect of spacing on physical, chemical and energy properties has not been precise for Eucalyptus tereticornis, which limits the development of plantations with optimal silvicultural conditions. Results: The study analyzed the growth and chemical, physical and energetic properties in a four-year-old plantation. The results showed that mortality ranged from 29 to 69%, being the 1.0 x 2.0 m spacing the one that presented better yields with a significantly higher diameter and height (9.13 cm and 14.17 m, respectively) with a higher biomass accumulation (140.04 ton ha -1 without treetop) concentrated mainly in the stem. The other two spacings presented statistically lower and non-significant values. The physical properties were obtained densities of 0.57 to 0.66 g cm -3, with a specific density of 0.58 and moisture content of 57.7%. The chemical properties only showed differences in carbon concentration (50.11 to 69.16%). The energetic properties showed a caloric power between 4780 to 6059 kcal kg -1, with a variation in volatile content of 10.9% and 1.6% in ash. Conclusion: The planting spacing generates a gradient in the production, mortality and property of the biomass, being the spacing of 1.0 x 2.0 m being optimum for establishing the study species for Costa Rica.

In Costa Rica, a diversification of the energy matrix has been developed, regarded as a source of energy of great potential in the short term. However, the current market is unclear and has multiple deficiencies that are necessary to identify and the government lacks studies that allow it to understand the current market. The study analyzed the perception of the biomass market with forest residues and agro-industrial in Costa Rica and their potential for development under a circular economy scheme. For that producers, intermediaries and consumers of arboreal and agro-industrial biomass in the North Zone of Costa Rica were employed, analyzing the market from a technical, environmental, financial and social perspective and identifying the variables that limit the market. The results showed similarity between agro-industrial and forest markets, as well as in ecological and social aspects, with similar perceptions between the sectors analyzed. However, the financial and technical elements presented significant differentiation, specifically in terms of the price of the biomass, homogeneity of the same (both species and presentation) and associated costs, in addition to the competence of other biomass fuels. The analysis showed that biomass variability in how much performance affects 42.5% of the market, species variation 24.8%, moisture content 10.6%, biomass availability in time 8.4%, organization and market structure 8.9% and other variables and 6.8%. If a market structure is needed in terms of biomass sales and articulation between producers and demanders together with key intermediaries for the viability of biomass market in Costa Rica.

Economies have begun to shift from linear to circular, adopting, among others, waste-to-energy approaches. Waste management is known to be a paramount challenge, and food waste (FW) in particular, has gained the interest of several actors due to its potential impacts and energy recovery opportunities. However, the selection of alternative valorization scenarios can pose several queries in certain contexts. This paper evaluates four FW valorization scenarios based on anaerobic digestion and composting, in comparison to landfilling, by applying a consistent decision-making framework through a combination of linear programming, Life Cycle Thinking (LCT), and Analytic Hierarchy Process (AHP). The evaluation was built upon a case study of five universities in Costa Rica and portrayed the trade-offs between environmental impacts and cost categories from the scenarios and their side flows. Results indicate that the landfill scenario entails higher Global Warming Potential and Fresh Water Eutrophication impacts than the valorization scenarios; however, other impact categories and costs are affected. Centralized recovery facilities can increase the Global Warming Potential and the Land Use compared to semi-centralized ones. Experts provided insights, regarding the ease of adoption of composting, in contrast to the potential of energy sources substitution and economic savings from anaerobic digestion.

El Pennisetum purpureum es una especie herbácea de rápido crecimiento con propiedades calorimétricas que la convierten en una especie con condiciones idóneas para ser implementada en proyectos biomásicos de generación eléctrica para Costa Rica. El presente estudio evaluó la factibilidad técnica y financiera de la especie dentro de condiciones de una plantación de alta densidad; para lo cual se estableció una plantación piloto de 12 hectáreas en Guanacaste, Costa Rica y se manejó con un ciclo productivo de 159 días y limitando su manejo a aplicaciones de tres dosis nutricionales de nitrógeno (85, 131 y 17 kg ha-1); posterior de la cosecha se evaluó la biomasa acumulada, el poder calórico y su viabilidad financiera para ser implementada en una caldera de 2 MW de potencia. Los resultados mostraron una cosecha de: 85 a 110 ton ha-1 de biomasa seca, encontrado los mayores valores en el tratamiento que usó mayor dosis de nitrógeno; también, se encontró que la biomasa seca de la especie es apenas del 24 % de la biomasa total, pero con un poder calórico superior a 3 800 cal g-1, que incidió en que el potencial eléctrico real fuera de 1,33 MWh ton-1 (considerando una caldera con una eficiencia del 30 %) suficiente para que una plantación de 200 ha con dos ciclos de cosecha al año y a una distancia inferior de 45 km de la planta pueda generar electricidad con una rentabilidad financieramente aceptable; el análisis financiero evidencio este tipo proyecto es viable siempre y cuando la producción de biomasa no sea menor a 120 ton ha-1, el costo del kilowatt hora sea inferior 0,10 USD y la plantaciones no estén a más de 45 km de la planta.