| 1. |
- Caceres Choque, Luis Fernando, et al.
(author)
-
Fractionation of heavy metals and assessment of contamination of the sediments of Lake Titicaca
- 2013
-
In: Environmental Monitoring & Assessment. - : Springer Science and Business Media LLC. - 0167-6369 .- 1573-2959. ; 185:12, s. 9979-9994
-
Journal article (peer-reviewed)abstract
- Chemical weathering is one of the major geochemical processes that control the mobilization of heavy metals. The present study provides the first report on heavy metal fractionation in sediments (8-156 m) of Lake Titicaca (3,820 m a.s.l.), which is shared by the Republic of Peru and the Plurinational State of Bolivia. Both contents of total Cu, Fe, Ni, Co, Mn, Cd, Pb, and Zn and also the fractionation of these heavy metals associated with four different fractions have been determined following the BCR scheme. The principal component analysis suggests that Co, Ni, and Cd can be attributed to natural sources related to the mineralized geological formations. Moreover, the sources of Cu, Fe, and Mn are effluents and wastes generated from mining activities, while Pb and Zn also suggest that their common source is associated to mining activities. According to the Risk Assessment Code, there is a moderate to high risk related to Zn, Pb, Cd, Mn, Co, and Ni mobilization and/or remobilization from the bottom sediment to the water column. Furthermore, the Geoaccumulation Index and the Enrichment Factor reveal that Zn, Pb, and Cd are enriched in the sediments. The results suggest that the effluents from various traditional mining waste sites in both countries are the main source of heavy metal contamination in the sediments of Lake Titicaca.
|
|
| 2. |
- Choque Campero, Luis Antonio, et al.
(author)
-
Biomass-based Brayton-Stirling-AGMD polygeneration for small-scale applications in rural areas
- 2024
-
In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 304
-
Journal article (peer-reviewed)abstract
- The lack of access to electricity and clean water still affects a substantial proportion of rural areas worldwide, in particular the global south. This paper presents a sustainable polygeneration system that can provide electricity, heat, and drinking water by using agricultural residues in remote rural areas. This polygeneration system consists of a solid biomass-fueled Brayton-Stirling combined cycle system, a boiler, and an air-gap membrane distillation unit. Four different system operation modes were designed to examine the most ideal configurations for maximizing power output, overall efficiency, and/or clean water production, considering a polygeneration system designed for a rural village with daily demands of 13450 kWh electricity and 7.5 m3 drinking water. A thermodynamic analysis are employed to analyze and compare these modes, each operating under steady state conditions. The highest electricity output, up to 160 kW, while the highest clean water is up to 0.7 m3/h. The fuel consumption can reach 0.9 kWh/kg of solid fuel and provide up to 0.0045 m3 of freshwater. In addition, nonlinear multi-objective optimization is used to meet the power demands of typical day in rural areas by varying the polygeneration operation modes and turbine inlet temperature.
|
|
| 3. |
- Choque Campero, Luis Antonio, 1986-
(author)
-
Brayton-Stirling-Membrane Distillation systems for clean energy and water access in rural Bolivia
- 2024
-
Doctoral thesis (other academic/artistic)abstract
- Remote rural areas in developing countries face significant challenges toward securing supplies of energy and clean water. This thesis presents an investigation of an innovative concept—Brayton-Stirling-Membrane Distillation cogeneration—for the simultaneous provision of electricity and water with particular focus on small scale, decentralized applications in rural areas of Bolivia. The considered Brayton and Stirling cycles are externally fired, allowing for utilization of a locally available energy resource (waste agricultural biomass) via standard combustion processes. Both cycles can be paired thermally to make use of cascaded heat, with additional low-grade heat used to drive water purification through membrane distillation.Thermodynamic analyses of each operation mode were used to assess the system performance. The performance of the operation modes ranges from 100-200 kW of produced electricity and up to 0.7 m3/h of drinking water. Parameters such as turbine inlet temperature, pressure ratio, regenerator effectiveness, and working fluid impact cogeneration efficiency. The turbine inlet temperature had the largest effect on the production of electricity and water. This study identified trends in water production and energy and exergy efficiency, emphasizing the capability of the system to generate both electricity and drinking water from agricultural residues. Multi-objective Nonlinear Programming (MNLP) was employed for dispatch optimization, considering factors such as an externally fired gas turbine inlet temperature range of 973 to 1123 K, minimum daily water demand of 7.5 m3 and typical hourly-daily electrical demand of 13450 kWh. The results demonstrate the system’s ability to meet dual objectives, electricity and clean water demand, while minimizing excess power and deficits. Expanding the scope, this thesis delves into a hybrid cogeneration system integrating PV panels, batteries, and the Brayton-Stirling-MD system. Geographical diversity was considered, emphasizing the adaptability of the system to varying solar irradiation, temperature, and altitude. Economic indicators for three villages of around 500 people, including Levelized Cost of Electricity (LCOE) and Levelized Cost of Clean Water (LCOW), are presented. The system currently lacks economic viability, but ongoing technological development and component integration will lead to cost reduction towards to accept level in the future.
|
|
| 4. |
- Choque Campero, Luis Antonio, et al.
(author)
-
Thermodynamic and exergetic analyses of a biomass-fired Brayton-Stirling cogeneration cycle for decentralized, rural applications
- 2023
-
In: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 292
-
Journal article (peer-reviewed)abstract
- Access to electricity in many remote rural areas of the world is wanting and often relies on decentralized concepts that are environmentally detrimental, costly, and unreliable. The purpose of this study was to examine an approach to meet this need that is based on an external biomass-fueled cogeneration system incorporating combined cycles for maximizing efficiency while ensuring robust operation. Specifically, the first and second laws of thermodynamics were analyzed in a system composed of a Brayton-Stirling cycle and a water boiler to compare efficiency, heat and electricity generation under three different power layouts of cogeneration for applications in the range of 100-200 kW electrical power output. The results show that overall efficiency is maximized at 85% with a hybrid power layout for cases where the turbine inlet temperature is 1273 K, the pressure ratio is 0.4, the regenerator effectiveness is 0.95, and the dead volume of the Stirling engine is 0.3. These findings provide a basis for implementing cogeneration systems to improve the reliability and robustness of power systems for rural electrification.
|
|
| 5. |
- Ramos, Oswaldo Eduardo, et al.
(author)
-
Arsenic fractionation in soils in mining region of the Bolivian Altiplano
- 2012
-
In: Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment. - : Taylor & Francis Group. - 9780415637633 ; , s. 335-336
-
Conference paper (peer-reviewed)abstract
- Cultivated soils in mining areas are degraded by natural and anthropogenic processes. A sequential extraction procedure in soils was conducted to fractionate the arsenic (As) content along a transect with active agriculture. The distribution of As in soil showed a small percentage on the exchangeable fraction, while a major As pool could be released depending on the crop and soil management.
|
|
| 6. |
|
|
