Environmental implications of decarbonising electricity supply in large economies: The case of Mexico

AbstractDriven by the security of supply and climate change concerns, decarbonisation of energy supply has become a priority for many countries. This study focuses on Mexico, the world’s 14th largest economy, and considers the environmental implications of decarbonising its electricity supply. Eleven scenarios are considered for the year 2050 with different technology mixes and GHG reduction targets, ranging from stabilisation at the year 2000 level to a reduction of 60–85%. Unlike most energy scenario analyses which focus mainly on direct CO2 or GHG emissions, this paper presents the full life cycle impacts of electricity generation in 2050 considering ten environmental impacts which, in addition to global warming, include resource and ozone layer depletion, acidification, eutrophication, summer smog, human and eco-toxicity. The results indicate that continuing with business as usual (BAU) would double the current life cycle GHG emissions, even if annual electricity demand growth was reduced to 2.25% from the current 2.8%. Switching from the current fossil fuel mix to a higher contribution of renewables (55–86%) and nuclear power (up to 30%) would lead to a significant reduction of all ten life cycle impacts compared to the current situation and up to an 80% reduction compared to BAU

Sustainability assessment of electricity options for Mexico : current situation and future scenarios

The aim of this research has been to identify the most sustainable options for electricity production in Mexico with an outlook to 2050. An integrated methodology for sustainability assessment of different electricity technologies and scenarios has been developed, taking into account environmental, economic and social aspects. The environmental impacts have been estimated using life cycle assessment; the economic costs considered include total capital and annualised costs while social aspects include security and diversity of energy supply, public acceptability, health and safety impacts and intergenerational issues. To help identify the most sustainable options, multi-criteria decision analysis has been used. The methodology has been applied to Mexican conditions for the assessment of both current and future electricity production. The results for the current situation show that on a life cycle basis 129 million tonnes of CO2 eq. are emitted annually from 225 TWh of electricity generated in Mexico. Heavy fuel oil, gas and coal power plants contribute together to 87% of CO2 eq. emissions. Total annualised costs are estimated at US$ 22.4 billion/yr with the fuel costs contributing 54%, mainly due to the operation of gas and heavy fuel oil power plants. A range of future scenarios up to 2050 has been developed in an attempt to identify the most sustainable options. The development of the scenarios has been driven and informed by the national greenhouse gas emission reduction target of 50% by 2050 on the 2000 levels, translating to an 85% reduction from the power sector. The results show that the business as usual (BAU) scenario (with the highest contribution from fossil fuels) is the least sustainable option with the CO2 eq. emissions increasing by almost 300% and the annualised costs by 290% for a projected electricity demand of 813 TWh in 2050. Overall, the most sustainable scenarios are those with higher penetration of renewable energies (wind, solar and hydro) and nuclear power, as in Green, A-3 and C-3. For example, compared to the BAU scenarios, the CO2 eq. emissions reduce by 84%, 89% and 89%, respectively. Although renewable energy based scenarios require high capital costs, the total annualised costs even out over time due to lower fuel costs. The lowest annualised costs are for C-3 scenario, representing a 40% reduction on BAU. With respect to social issues, the BAU scenario is also the least preferred option with the highest risks related to security and diversity of supply, health and safety and climate change. The most sustainable options are scenarios A-3 and Green, with social barriers related to public acceptability, reliability of supply and availability of energy resource. Most critical aspects for scenario C-3 are health and safety risks, and intergenerational issues related to nuclear power. Therefore, the Mexican Government should aim to strengthen the current low carbon energy policies as well as put measures in place to encourage reducing the electricity demand. In the case of the energy policy driver focusing on climate change mitigation or annualised costs, scenarios A-3 and C-3 are the most sustainable options.EThOS - Electronic Theses Online ServiceMexican Council of Science and Technology (CONACyT)Mexican Ministry of Education (SEP)GBUnited Kingdo

Pharmacodynamics of Aerosolized Fosfomycin and Amikacin against Resistant Clinical Isolates of Pseudomonas aeruginosa and Klebsiella pneumoniae in a Hollow-Fiber Infection Model: Experimental Basis for Combination Therapy

There has been a resurgence of interest in aerosolization of antibiotics for treatment of patients with severe pneumonia caused by multidrug-resistant pathogens. A combination formulation of amikacin-fosfomycin is currently undergoing clinical testing although the exposure-response relationships of these drugs have not been fully characterized. The aim of this study was to describe the individual and combined antibacterial effects of simulated epithelial lining fluid exposures of aerosolized amikacin and fosfomycin against resistant clinical isolates of Pseudomonas aeruginosa (MICs of 16 mg/liter and 64 mg/liter) and Klebsiella pneumoniae (MICs of 2 mg/liter and 64 mg/liter) using a dynamic hollow-fiber infection model over 7 days. Targeted peak concentrations of 300 mg/liter amikacin and/or 1,200 mg/liter fosfomycin as a 12-hourly dosing regimens were used. Quantitative cultures were performed to describe changes in concentrations of the total and resistant bacterial populations. The targeted starting inoculum was 108 CFU/ml for both strains. We observed that neither amikacin nor fosfomycin monotherapy was bactericidal against P. aeruginosa while both were associated with rapid amplification of resistant P. aeruginosa strains (about 108 to 109 CFU/ml within 24 to 48 h). For K. pneumoniae, amikacin but not fosfomycin was bactericidal. When both drugs were combined, a rapid killing was observed for P. aeruginosa and K. pneumoniae (6-log kill within 24 h). Furthermore, the combination of amikacin and fosfomycin effectively suppressed growth of resistant strains of P. aeruginosa and K. pneumoniae. In conclusion, the combination of amikacin and fosfomycin was effective at maximizing bacterial killing and suppressing emergence of resistance against these clinical isolates

Population Pharmacokinetics and Cerebrospinal Fluid Penetration of Fluconazole in Adults with Cryptococcal Meningitis

Robust population pharmacokinetic (PK) data for fluconazole are scarce. The variability of fluconazole penetration into the CNS is not known. A fluconazole PK study was conducted in 43 patients receiving oral fluconazole (usually 800 mg q24h) in combination with amphotericin B deoxycholate (1 mg/kg q24h) for cryptococcal meningitis (CM). A 4-compartment PK model was developed and Monte Carlo simulations performed for a range of fluconazole dosages. A meta-analysis of trials reporting outcomes of CM patients treated with fluconazole monotherapy was performed. Adjusted for bioavailability, the PK parameter means (standard deviation) were: clearance, 0.72 (0.24) litres/hour; volume of the central compartment, 18.07 (6.31) litres; volume of central nervous system (CNS) compartment, 32.07 (17.60) litres; first-order rate constant from central to peripheral compartment, 12.20 (11.17) hours-1; from peripheral to central compartment, 18.10 (8.25) hours-1; from central to CNS compartment 35.43 (13.74) hours-1; from CNS to central compartment 28.63 (10.03) hours-1 Simulations of area under concentration-time curve resulted in median (interquartile range) values 1143.2 mg.h/litre (988.4 - 1378.0) in plasma and 982.9 (781.0 - 1185.9) in CSF after a dosage of 1200mg q24h. The mean simulated ratio of AUCCSF:AUCplasma was 0.89 (SD 0.44). The recommended dosage of fluconazole for CM induction therapy fails to attain the PD target in respect to the wild-type MIC distribution of C. neoformans The meta-analysis suggested modest improvements in both CSF sterility and mortality outcomes with escalating dosage. This study provides the pharmacodynamic rationale for the long-recognised fact that fluconazole monotherapy is an inadequate induction regimen for CM