Science for sustainability: From capturing carbon dioxide from air to environmental impact of a hydrogen economy

Manvendra K. Dubey
Los Alamos National Laboratory

Wednesday, April 2, 2003
3:00 p.m. – Pacific Forum

Sustaining our technological society demands innovative science to assess and minimize its global impact. We propose active management of anthropogenic emissions by developing efficient technologies and engineering effective sinks to close nature’s biogeochemical cycles. 

Fossil energy has benefited humankind, but also threatens our environment. Given that fossil fuels are plentiful, cost-effective, and energy rich, their use will be limited by our ability to mitigate their environmental impact. To achieve this, current approaches focus on capturing CO2 from large point sources such as power plants. 

Dubey1web.jpg (26720 bytes)However, they are limited because they fail to address emissions from transportation and the myriad of dispersed sources that amount to more than half of all emissions. To solve this problem, we are developing direct CO2 extraction from air as a means to capture emissions from all sources. It preserves our energy infrastructure, fuel distribution, and transportation systems, eliminates piping costs to permanent CO2 sequestration sites, and could restore atmospheric CO2 to pre-industrial levels. Our approach binds CO2 in the air (370 ppm) to an adsorbent, which is then heated to recover a pure CO2 stream for sequestration and the adsorbent for recycling. Adsorbents, like lime, that are used in the cement industry are identified as a prototype. We report laboratory experiments on several adsorbents and atmospheric modeling results to better assess the scale and scope of air-capture as a means to sustain fossil energy. 

Dubey2web.jpg (26268 bytes)Rapid development in hydrogen (H2) fuel-cell technologies will create a strong impetus for H2 supply and distribution infrastructure in the coming decades. H2 energy promises a sustainable future by enhancing urban air quality, and reducing risks of climate change. While it is well known that the byproduct of energy produced from H2 fuel cells is simply water vapor, it is not well known that the storage and transfer of H2 is inevitably accompanied by measurable leakage of H2. Unintended consequences of H2 leakage include reduction in global oxidative capacity, increase in tropospheric ozone, and increase in stratospheric water that would exacerbate halogen induced ozone losses. We assess these impacts using global 3-D simulations by the Model for Ozone And Related Trace species (MOZART).

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