Environmental science & technology
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Environ. Sci. Technol. · Dec 2016
Viability of Carbon Capture and Sequestration Retrofits for Existing Coal-Fired Power Plants under an Emission Trading Scheme.
Using data on the coal-fired electric generating units (EGUs) in Texas we assess the economic feasibility of retrofitting existing units with carbon capture and sequestration (CCS) in order to comply with the Clean Power Plan's rate-based emission standards under an emission trading scheme. CCS with 90% capture is shown to be more economically attractive for a range of existing units than purchasing emission rate credits (ERCs) from a trading market at an average credit price above $28 per MWh under the final state standard and $35 per MWh under the final national standard. ⋯ The combination of ERC trading and CO2 use can greatly reinforce economic incentives and market demands for CCS and hence accelerate large-scale deployment, even under scenarios with high retrofit costs. Comparing the levelized costs of electricity generation between CCS retrofits and new renewable plants under the ERC trading scheme, retrofitting coal-fired EGUs with CCS may be significantly cheaper than new solar plants under some market conditions.
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Environ. Sci. Technol. · Dec 2016
Flavoring Compounds Dominate Toxic Aldehyde Production during E-Cigarette Vaping.
The growing popularity of electronic cigarettes (e-cigarettes) raises concerns about the possibility of adverse health effects to primary users and people exposed to e-cigarette vapors. E-Cigarettes offer a very wide variety of flavors, which is one of the main factors that attract new, especially young, users. How flavoring compounds in e-cigarette liquids affect the chemical composition and toxicity of e-cigarette vapors is practically unknown. ⋯ We show that, within the tested e-cigarette brands, thermal decomposition of flavoring compounds dominates formation of aldehydes during vaping, producing levels that exceed occupational safety standards. Production of aldehydes was found to be exponentially dependent on concentration of flavoring compounds. These findings stress the need for a further, thorough investigation of the effect of flavoring compounds on the toxicity of e-cigarettes.