Scientific investigations and observations show that carbon dioxide is a major contributor to the increasingly damaging effects of global warming. Thus, geological sequestration of carbon dioxide in saline aquifers is already in operations across the globe. However, geological carbon sequestration in an aquifer should be safeguarded from CO2 leakage into the atmosphere and/or CO2 migration into potable water aquifers that are also present in the subsurface. To promote safety of living and non-living species that are near and far from the geological sequestration sites, this work presents techniques for monitoring the greenhouse gas stored in geological porous media, using experiments and numerical simulation techniques. The work employed two-phase flow parameters like capillary pressure (Pc), bulk electrical conductivity (σb), dielectric permittivity (εb) and their respective relationship with water saturation (S). Pc-S relationship was found to rise with increasing rate of CO2 injection while εb–S and σb-S relationships were not affected by the injection rate of CO2. Thus, it can be inferred that the εb–S and σb-S relationships will be more reliable in application to the monitoring of CO2 plume in geological carbon sequestration. On the other hand, εb–S and σb-S relationships are found to be affected by temperature. While εb–S decreases with temperature, σb-S relationship shows opposite behavior, rising with increasing temperature. Also, in different porous media, εb–S and σb-S relationships remained higher in limestone than silica sand. Finally, the numerical simulation was used to corroborate the experimental observations in Pc-S relationship. This work draws the attention of the stakeholders in climate change mitigation to the challenges involved in risk aversion techniques that are currently in existence.
Retraction Notice: This paper has been retracted from the journal after receipt of written complains. This journal is determined to promote integrity in research publication. This retraction is in spirit of the same. After formal procedures editor(s) and publisher have retracted this paper on 5th March-2016. Related policy is available here: http://goo.gl/lI77Nn
In the recent attempts to stimulate alternative energy sources for heating and cooling of buildings, emphasise has been put on utilisation of the ambient energy from ground source heat pump systems (GSHPs) and other renewable energy sources. Exploitation of renewable energy sources and particularly ground heat in buildings can significantly contribute towards reducing dependency on fossil fuels. Geothermal heat pumps (GSHPs), or direct expansion (DX) ground source heat pumps, are a highly efficient renewable energy technology, which uses the earth, groundwater or surface water as a heat source when operating in heating mode or as a heat sink when operating in a cooling mode. It is receiving increasing interest because of its potential to reduce primary energy consumption and thus reduce emissions of the greenhouse gases (GHGs). The main concept of this technology is that it utilises the lower temperature of the ground (approximately <32°C), which remains relatively stable throughout the year, to provide space heating, cooling and domestic hot water inside the building area. The main goal of this study is to stimulate the uptake of the GSHPs. Recent attempts to stimulate alternative energy sources for heating and cooling of buildings has emphasised the utilisation of the ambient energy from ground source and other renewable energy sources. The purpose of this study, however, is to examine the means of reduction of energy consumption in buildings, identify GSHPs as an environmental friendly technology able to provide efficient utilisation of energy in the buildings sector, promote using GSHPs applications as an optimum means of heating and cooling, and to present typical applications and recent advances of the DX GSHPs. The study highlighted the potential energy saving that could be achieved through the use of ground energy sources. It also focuses on the optimisation and improvement of the operation conditions of the heat cycle and performance of the DX GSHP. It is concluded that the direct expansion of the GSHP, combined with the ground heat exchanger in foundation piles and the seasonal thermal energy storage from solar thermal collectors, is extendable to more comprehensive applications.
An empirical study was carried out to assess the effect of intensive vegetable cultivation on the amount of soil carbon stored in Abak, Onna, Uyo and Ikot Ekpene area of Akwa Ibom State, Southeastern Nigerian. The objectives of the study were to; assess the types of farming practices in the study area, characterize the physical and chemical properties of soils, quantify the amount and types of organic carbon stored as well as assessing the functional pool of soil organic carbon. Random and systematic sampling techniques were used for the collection of soil samples. Data was analyzed using descriptive and inferential statistics. The results showed that the average amount of soil carbon sequestered was similar among the study locations, ranging from 497.4 to Mgha-1 in Abak to 576.7 Mgha-1 in Uyo. The average amount of carbon stored in the uncultivated soil range from 417.3 Mgha-1 in Uyo to 799.0 Mgha-1 in Abak. On the average, the amount of carbon stored in the uncultivated soil was 575.6 Mgha-1 greater than 535.2 Mgha-1 in the cultivated area by about 7%. The results also showed that potential mineralized carbon (PMC) was also similar among the locations, ranging from 4.20 MgC02- C ha-1 in Uyo to 5.04 MgC02- C ha-1 in Ikot Ekpene cultivated area. In the uncultivated area, PMC range from 3.01 MgC02- C ha-1 in Onna to 5.24 MgC02- C ha-1 in Ikot Ekpene. Soil carbon storage can be improved by the application of organic manures and use of planted fallows in the cultivated areas.
Aims: As climate change related rainfall and temperature variability is being increasingly experienced in the SAT regions, we assessed climate change mitigation and adaptation potential of Conservation Agriculture (CA) by studying effects of minimum tillage (MT) and residue management practices on rain water use efficiency (RWUE), soil moisture, runoff, energy use and carbon dioxide emission in two maize-legume cropping systems.
Study Design: The experiment was laid out in split-split plot design with four replications.
Place and Duration of Study: The study was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) farm, Patancheru, Telangana, India during 2010-11 and 2011-12.
Methodology: RWUE was calculated as maize equivalent yield divided by rainfall received during the crop season. Integrated digital runoff and soil loss monitoring unit (IDRSMU) was used to measure runoff. Soil moisture content was measured using the gravimetric method (0-30 cm depth) and neutron probe (60-90 cm depth). The soil organic carbon was analyzed following the Walkley-Black method . The diesel consumption in MT and conventional tillage (CT) was estimated following Downs and Hansen (http://www.ext.colostate.edu/pubs) and emission of CO2 was estimated according to EPA, 2009 .
Results: Tillage and residue management practices did not show significant effect on RWUE except; CT having significantly higher RWUE over MT during 2011-12. Effect of cropping systems on RWUE was significant but variable during the two years of study. MT-RT (minimum tillage- residue retained) reduced total seasonal runoff by 28.62% and 80.22% compared to CT-RR (conventional tillage- residue removed) in 2010-11 and 2011-12, respectively. Similarly, MT-RT reduced rainwater loss and peak rate of runoff compared to CT-RR in both the years of study. During 2010, MT-RT had higher total soil moisture (v/v) in the 0-90 cm soil depth in sole as well as intercropped maize compared to CT-RR, however, during 2011 MT-RT had higher total soil moisture in sole maize only. As compared to CT, even though, MT improved SOC in 0-15 cm depth but lowered slightly in 15-30 cm depth. RT (residue retained) improved SOC in 0-15 and 15-30 cm depths compared to residue removal (RR). MT-RT had higher or equal SOC in 0-15 and 15-30 cm soil depths compared to CT-RR in both the maize-legume cropping systems. MT saved energy corresponding to 41.49 l of diesel per hectare annually compared to CT. Similarly, MT emitted 110.79 kg less CO2 annually on per hectare basis compared to CT due to reduced diesel use.
Conclusion: CA, when adopted by following good agricultural practices and refined to suit the local conditions, could emerge as sustainable production system for climate change mitigation and adaptation of dryland cropping systems in semi-arid tropics of southern India.
Aims: Analysis of risk, farmer’s perceptions on risk and their adaptation practices through exploration of agriculture based farmer’s community perceptions were lack on the perspective of Angaria sub-sub-district of Dumki sub-district of Patuakhali district in Bangladesh. That is why this study was conducted to gain understanding on agriculture farmers' risk profile, its impact and potential risk reduction strategy through community participation.
Study Design: A total of 23 Focus Group Discussion’s (FGD) and 04 Key Informant Interviews (KII) were conducted. A well structured pretested questionnaire schedule was developed keeping in mind the objectives and variables under this study.
Place and Duration of Study: Angaria sub-sub-district of Dumki sub-district of Patuakhali district in Bangladesh, from January, 2015 to May, 2015.
Methodology: Primary data was collected through face to face FGD, KII methods and extensive field visit. Secondary data was collected from different secondary sources.
Results: The agriculture sector of the study area is potentially exposed by different primary and secondary risk factors such as cyclone, flood, drought, pest attack etc. which threats to agriculture production and pose the farmers to make their livelihood diversified. But due to the changing trend in risk profiles; increasing its persistence time and frequency and intensity, farmers' adaptation capacities and sustainability are more exposed to vulnerability and adaptive capacity of the farmers are decreasing in the study area. They are transforming from on-farm agriculture practices to nonfarm alternative livelihood options –not as innovative adaptive resilient options.
Conclusion: Recurring disasters phenomena threatened and undermined farmers capacity to adaptations, resulted more dependence on alternative nonfarm livelihood options than appropriate on farm adaptive options. Future extensive field based research in these regards will fulfill the required information to get the most efficient small farmers friendly risk management plan which will be beneficiary to the country by establishing climate smart disaster risk management in agriculture sector.