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- Clack, Christopher T. M., et al.
(författare)
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Evaluation of a proposal for reliable low-cost grid power with 100% wind, water, and solar
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 114:26, s. 6722-6727
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Tidskriftsartikel (refereegranskat)abstract
- A number of analyses, meta-analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy Agency, have concluded that deployment of a diverse portfolio of clean energy technologies makes a transition to a low-carbon-emission energy system both more feasible and less costly than other pathways. In contrast, Jacobson et al. [Jacobson MZ, Delucchi MA, Cameron MA, Frew BA (2015) Proc Natl Acad Sci USA 112(49): 15060-15065] argue that it is feasible to provide "low-cost solutions to the grid reliability problem with 100% penetration of WWS [wind, water and solar power] across all energy sectors in the continental United States between 2050 and 2055", with only electricity and hydrogen as energy carriers. In this paper, we evaluate that study and find significant shortcomings in the analysis. In particular, we point out that this work used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions. Policy makers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that relies almost exclusively on wind, solar, and hydroelectric power.
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| 2. |
- Schneider, Kenneth, et al.
(författare)
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Potential influence of sea cucumbers on coral reef CaCO(3) budget : A case study at One Tree Reef
- 2011
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116, s. G04032-
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Tidskriftsartikel (refereegranskat)abstract
- To endure, coral reefs must accumulate CaCO(3) at a rate greater or equal than the sum of mechanically, biologically, and chemically mediated erosion rates. We investigated the potential role of holothurians on the CaCO(3) balance of a coral reef. These deposit feeders process carbonate sand and rubble through their digestive tract and dissolve CaCO(3) as part of their digestive process. In aquarium incubations with Stichopus herrmanni and Holothuria leucospilota total alkalinity increased by 97 +/- 13 and 47 +/- 7 mu mol kg(-1), respectively. This increase was due to CaCO3 dissolution, 81 +/- 13 and 34 +/- 6 mu mol kg(-1) and ammonia secretion, 16 +/- 2 and 14 +/- 2 mu mol kg(-1), respectively, for these species. Surveys conducted at a long-term monitoring site of community calcification (DK13) on One Tree Reef indicated that the density of sea cucumbers was approximately 1 individual m(-2). We used these data and data from surveys at Shark Alley to estimate the dissolution of CaCO(3) by the sea cucumbers at both sites. At DK13 the sea cucumber population was estimated to be responsible for nearly 50% of the nighttime CaCO(3) dissolution, while in Shark Alley for most of the nighttime dissolution. Thus, in a healthy reef, bioeroders dissolution of CaCO(3) sediment appears to be an important component of the natural CaCO(3) turnover and a substantial source of alkalinity as well. This additional alkalinity could partially buffer changes in seawater pH associated with increasing atmospheric CO(2) locally, thus reducing the impact of ocean acidification on coral growth.
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