Global energy consumption is projected to increase, even in the face of substantial declines in energy intensity, at least 2-fold by midcentury relative to the present because of population and economic growth. This demand could be met, in principle, from fossil energy resources, particularly coal. However, the cumulative nature of CO2 emissions in the atmosphere demands that holding atmospheric CO2 levels to even twice their preanthropogenic values by midcentury will require invention, development, and deployment of schemes for carbon-neutral energy production on a scale commensurate with, or larger than, the entire present-day energy supply from all sources combined. Among renewable energy resources, solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year. In view of the intermittency of insolation, if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user. An especially attractive approach is to store solar-converted energy in the form of chemical bonds, i.e., in a photosynthetic process at a year-round average efficiency significantly higher than current plants or algae, to reduce land-area requirements. Scientific challenges involved with this process include schemes to capture and convert solar energy and then store the energy in the form of chemical bonds, producing oxygen from water and a reduced fuel such as hydrogen, methane, methanol, or other hydrocarbon species.

/pdf/powering-the-planet-chemical-challenges-in-solar-energy-1kb0jbsg7k.pdf

Powering the planet: Chemical challenges in solar energy utilization

Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2 degrees C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.

/pdf/coral-reefs-under-rapid-climate-change-and-ocean-398ioolbkj.pdf

Coral Reefs Under Rapid Climate Change and Ocean Acidification

On 13 October 1908, Fritz Haber filed his patent on the "synthesis of ammonia from its elements" for which he was later awarded the 1918 Nobel Prize in Chemistry. A hundred years on we live in a world transformed by and highly dependent upon Haber–Bosch nitrogen.

How a century of ammonia synthesis changed the world

We present the greenhouse gas concentrations for the Representative Concentration Pathways (RCPs) and their extensions beyond 2100, the Extended Concentration Pathways (ECPs). These projections include all major anthropogenic greenhouse gases and are a result of a multi-year effort to produce new scenarios for climate change research. We combine a suite of atmospheric concentration observations and emissions estimates for greenhouse gases (GHGs) through the historical period (1750-2005) with harmonized emissions projected by four different Integrated Assessment Models for 2005-2100. As concentrations are somewhat dependent on the future climate itself (due to climate feedbacks in the carbon and other gas cycles), we emulate median response characteristics of models assessed in the IPCC Fourth Assessment Report using the reduced-complexity carbon cycle climate model MAGICC6. Projected 'best-estimate' global-mean surface temperature increases (using inter alia a climate sensitivity of 3°C) range from 1.5°C by 2100 for the lowest of the four RCPs, called both RCP3-PD and RCP2.6, to 4.5°C for the highest one, RCP8.5, relative to pre-industrial levels. Beyond 2100, we present the ECPs that are simple extensions of the RCPs, based on the assumption of either smoothly stabilizing concentrations or constant emissions: For example,

/pdf/the-rcp-greenhouse-gas-concentrations-and-their-extensions-2lai11z83a.pdf

The RCP greenhouse gas concentrations and their extensions from 1765 to 2300

Humanity already possesses the fundamental scientific, technical, and industrial know-how to solve the carbon and climate problem for the next half-century. A portfolio of technologies now exists to meet the world’s energy needs over the next 50years and limit atmospheric CO 2 to a trajectory that avoids a doubling of the preindustrial concentration. Every element in this portfolio has passed beyond the laboratory bench and demonstration project; many are already implemented somewhere at full industrial scale. Although no element is a credible candidate for doing the entire job (or even half the job) by itself, the portfolio as a whole is large enough that not every element has to be used.

/pdf/stabilization-wedges-solving-the-climate-problem-for-the-2484ljmpvo.pdf

Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies

Author(s): Nakicenovic, N.; Alcamo, J.; Davis, G.; Vries, B. de; Fenhann, J.; Gaffin, S.; Gregory, K.; Grubler, A.; Jung, T.Y.; Kram, T.; Rovere, E.L. La; Michaelis, L.; Mori, S.; Morita, T.; Pepper, W.; Pitcher, H.; Price, L.; Riahi, K.; Roehrl, A.; Rogner, H-H.; Sankovski, A.; Schlesinger, M.; Shukla, P.; Smith, S.; Swart, R.; Rooijen, S. van; Victor, N.; Zhou, D.

/pdf/special-report-on-emissions-scenarios-41cfult637.pdf

Special report on emissions scenarios

A temperature-compensated sensor architecture for a fiber optic hydrogen sensor consisting of a partly palladium-coated pi-shifted fiber Bragg grating was modeled and compared with measurements. The transfer matrix formalism was used to calculate the spectral line shape of the pi-shifted FBG with a hydrogen-induced, non-homogeneous strain distribution along the grating axis. The temperature response of the grating itself can be compensated by referencing the notch to the flank wavelength. In addition, the hydrogen solubility in Pd shows a non-linear temperature dependence that was also included in the sensor performance calculations. For the investigated H2 concentration range of 200 ppm to 20000 ppm and between 15 °C and 40 °C, measurement data fit well to the simulation above 3000 ppm but become diffuse below, indicating deviations from the expected dependence according to Sieverts’ square root law.

Simulation of a temperature-compensated palladium-based fiber optic hydrogen sensor and comparison with measurements

Comparison of Broadband Loss in Fiber Bragg Gratings Manufactured with UV Phase Mask and Direct Writing Techniques

Hydrogen sensing performance of partially Pd90:Ni10-coated pi-FBGs in nitrogen and air backgrounds

Palladium/hafnium-coated pi-FBGs: a path to wavelength-encoded, zero-point-referenced, linearized, and temperature-decoupled hydrogen sensing

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