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You searched for +publisher:"Harvard University" +contributor:("Keith, David"). Showing records 1 – 2 of 2 total matches.

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Harvard University

1. Dagon, Katherine. Exploring the Climate Impacts of Solar Geoengineering on Land-Atmosphere Interactions.

Degree: PhD, 2017, Harvard University

We are already on our way to a much warmer world. As humans continue to emit greenhouse gases into the atmosphere, avoiding the worst increases in surface temperature will likely require climate mitigation or even climate intervention. Solar geoengineering refers to a set of proposed methods to mitigate climate changes from greenhouse warming by manipulating the incoming solar radiation. To fully understand the consequences of solar geoengineering, research is needed to examine the impacts it will have on the climate system and understand how those impacts compare to the climate changes induced by a warming world. This thesis explores the climate impacts of solar geoengineering in a modeling context, focusing in particular on land-atmosphere coupling, terrestrial water cycling, regional climate variability, and vegetation-climate interactions. Modeling studies have demonstrated the potential of solar geoengineering to compensate temperature increases from climate change. We examine changes in the terrestrial hydrologic cycle under global model simulations of solar geoengineering and increased greenhouse gas forcing. The interactions between vegetation water cycling and climate drive global and regional changes when uniform solar reductions are used to compensate elevated carbon dioxide (CO2) levels. We expand our modeling framework to utilize multiple large ensembles of simulations to examine how climate variability is impacted by solar geoengineering on a regional scale. Summer heat extremes decrease under solar geoengineering relative to a high-CO2 climate, and in some cases extremes decrease relative to present-day climate. The coupling between soil moisture and daily maximum temperature is identified as a key mechanism in driving the variability response. We explore the sensitivity of land surface model parameters using a state-of- the-art land surface model. We identify the parameters which soil moisture and evapotranspiration are most sensitive to, based on possible ranges of values from the literature. Our results provide a foundation for understanding and interpreting the land surface feedbacks and mechanisms identified by the solar geoengineering modeling studies in this thesis. We return to a global coupled modeling framework and examine impacts on terrestrial ecosystems under solar geoengineering designed to hold anthropogenic radiative forcing fixed, relative to a mid-range future emissions scenario. Although potential changes in biodiversity are not completely avoided, the outlook for conservation improves under solar geoengineering relative to a warming climate.

Earth and Planetary Sciences

Climate science; climate modeling; land-atmosphere interactions; solar geoengineering

Advisors/Committee Members: Schrag, Daniel (committee member), Huybers, Peter (committee member), Keith, David (committee member), Keutsch, Frank (committee member).

Subjects/Keywords: Atmospheric Sciences

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Dagon, K. (2017). Exploring the Climate Impacts of Solar Geoengineering on Land-Atmosphere Interactions. (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:39987917

Chicago Manual of Style (16th Edition):

Dagon, Katherine. “Exploring the Climate Impacts of Solar Geoengineering on Land-Atmosphere Interactions.” 2017. Doctoral Dissertation, Harvard University. Accessed December 12, 2019. http://nrs.harvard.edu/urn-3:HUL.InstRepos:39987917.

MLA Handbook (7th Edition):

Dagon, Katherine. “Exploring the Climate Impacts of Solar Geoengineering on Land-Atmosphere Interactions.” 2017. Web. 12 Dec 2019.

Vancouver:

Dagon K. Exploring the Climate Impacts of Solar Geoengineering on Land-Atmosphere Interactions. [Internet] [Doctoral dissertation]. Harvard University; 2017. [cited 2019 Dec 12]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:39987917.

Council of Science Editors:

Dagon K. Exploring the Climate Impacts of Solar Geoengineering on Land-Atmosphere Interactions. [Doctoral Dissertation]. Harvard University; 2017. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:39987917

2. Safaei Mohamadabadi, Hossein. Techno-Economic Assessment of the Need for Bulk Energy Storage in Low-Carbon Electricity Systems With a Focus on Compressed Air Storage (CAES).

Degree: PhD, 2015, Harvard University

Increasing electrification of the economy while decarbonizing the electricity supply is among the most effective strategies for cutting greenhouse gas (GHG) emissions in order to abate climate change. This thesis offers insights into the role of bulk energy storage (BES) systems to cut GHG emissions from the electricity sector. Wind and solar energies can supply large volumes of low-carbon electricity. Nevertheless, large penetration of these resources poses serious reliability concerns to the grid, mainly because of their intermittency. This thesis evaluates the performance of BES systems – especially compressed air energy storage (CAES) technology – for integration of wind energy from engineering and economic aspects. Analytical thermodynamic analysis of Distributed CAES (D CAES) and Adiabatic CAES (A CAES) suggest high roundtrip storage efficiencies (~80% and 70%) compared to conventional CAES (~50%). Using hydrogen to fuel CAES plants – instead of natural gas – yields a low overall efficiency (~35%), despite its negligible GHG emissions. The techno-economic study of D CAES shows that exporting compression heat to low-temperature loads (e.g. space heating) can enhance both the economic and emissions performance of compressed air storage plants. A case study for Alberta, Canada reveals that the abatement cost of replacing a conventional CAES with D CAES plant practicing electricity arbitrage can be negative (-$40 per tCO2e, when the heat load is 50 km away from the air storage site). A green-field simulation finds that reducing the capital cost of BES – even drastically below current levels – does not substantially impact the cost of low-carbon electricity. At a 70% reduction in the GHG emissions intensity of the grid, gas turbines remain three times more cost-efficient in managing the wind variability compared to BES (in the best case and with a 15-minute resolution). Wind and solar thus, do not need to wait for availability of cheap BES systems to cost-effectively decarbonize the grid. The prospects of A CAES seem to be stronger compared to other BES systems due to its low energy-specific capital cost. Advisors/Committee Members: Keith, David W. xmlui.authority.confidence.description.cf_ambiguous (advisor), Aziz, Michael J. (committee member), Apt, Jay (committee member), Vecitis, Chad (committee member).

Subjects/Keywords: Energy; Engineering, Mechanical; Environmental Sciences

…NSERC). My studies were also supported by the Harvard University Center for Environment… …for my research. I was privileged to learn from world-class scholars both at Harvard… …University and University of Calgary. Michael Aziz, Dan Schrag, Meghan O Sullivan John Shaw and… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Safaei Mohamadabadi, H. (2015). Techno-Economic Assessment of the Need for Bulk Energy Storage in Low-Carbon Electricity Systems With a Focus on Compressed Air Storage (CAES). (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226038

Chicago Manual of Style (16th Edition):

Safaei Mohamadabadi, Hossein. “Techno-Economic Assessment of the Need for Bulk Energy Storage in Low-Carbon Electricity Systems With a Focus on Compressed Air Storage (CAES).” 2015. Doctoral Dissertation, Harvard University. Accessed December 12, 2019. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226038.

MLA Handbook (7th Edition):

Safaei Mohamadabadi, Hossein. “Techno-Economic Assessment of the Need for Bulk Energy Storage in Low-Carbon Electricity Systems With a Focus on Compressed Air Storage (CAES).” 2015. Web. 12 Dec 2019.

Vancouver:

Safaei Mohamadabadi H. Techno-Economic Assessment of the Need for Bulk Energy Storage in Low-Carbon Electricity Systems With a Focus on Compressed Air Storage (CAES). [Internet] [Doctoral dissertation]. Harvard University; 2015. [cited 2019 Dec 12]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226038.

Council of Science Editors:

Safaei Mohamadabadi H. Techno-Economic Assessment of the Need for Bulk Energy Storage in Low-Carbon Electricity Systems With a Focus on Compressed Air Storage (CAES). [Doctoral Dissertation]. Harvard University; 2015. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:14226038

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