Entity

Time filter

Source Type

Madrid, Spain

Oltra C.,CIEMAT
Energy Policy | Year: 2011

In this paper we focus on stakeholder views around the development of advanced biofuels from microalgae. Research for the development of microalgal-derived biofuels was initiated by the US Department of Energy (DOE) more than 30 years ago. However, interest in this eco-innovation has been growing significantly over the last five years in various countries. The high productivity of algae indicates that algal biofuels could contribute to reduce our dependence on fossil fuels while avoiding the undesired impacts of first generation biofuels. There are still numerous challenges that need nevertheless to be addressed. The aim of this paper is to explore stakeholder perceptions of the current barriers and opportunities associated with this promising emergent technology. © 2011 Elsevier Ltd. Source


The propagation of premixed flames with different Lewis numbers in a planar channel subject to a Poiseuille flow is considered within the diffusive-thermal model for steady and time-dependent cases. It was found that, depending on the Lewis number and the flow rate, symmetric and non-symmetric flames are possible. The existence of multiple steady solutions in cases of the low Lewis number is demonstrated. The time-dependent simulations carried out for high Lewis number flames also showed the symmetric and non-symmetric oscillatory solutions. Linear stability analysis of two-dimensional steady-states was performed using a practical method developed in the paper and applied to calculate the main eigenvalue. It was shown that for symmetric flames with a low Lewis number the increase in the flow rate leads to a loss of stability with subsequent formation of non-symmetric solutions. For flames with a high Lewis number the Poiseuille flow produces a stabilization effect. The results of the stability analysis were successfully compared with the results of direct numerical simulations. © 2010 The Combustion Institute. Source


Kurdyumov V.N.,CIEMAT
Combustion and Flame | Year: 2011

A systematic study of the diffusive-thermal instability of premixed tubular flames is carried out. The problem becomes amenable to a complete analysis in the frame of the diffusive-thermal approximation when a simplified flow field and the flame-sheet combustion model are used. The dispersion relation determining the growth rate of instability is obtained in an analytical form which therefore analyzed numerically. Stability diagrams showing stable and unstable states, in particular those manifesting the cellular flames, are presented. © 2011 The Combustion Institute. Source


Deployment of the first generation of grid-connected plants for electricity production, based on Solar Thermal Power Plants with Central Receiver System technology using large heliostat fields and a solar receiver placed on the top of a tower, is currently being boosted by the first commercial plants in Spain, PS10, PS20, and Gemasolar. Therefore one of the main goals of solar technology research is the study of existing receivers and development of new designs to minimize heat losses. In this context, volumetric receivers appear to be the best alternative to tube receivers, mainly due to their functionality and geometric configuration. They consist of a porous material that absorbs concentrated radiation inside the volume of a structure and transfers the absorbed heat to a fluid passing through the structure. Solar radiation is first converted into thermal energy or chemical potential, and then at a later stage, into electricity. This volumetric receiver technology has been under development since the early 1990s in various research and development projects. This paper is a chronological review of the volumetric receivers of most interest for electricity production, identifying their different configurations, materials and real and expected results, and pointing out their main advantages and conclusions based on the multitude of international and national projects reports and references. This study also deals with other important issues surrounding the volumetric receiver, such as the basic plant configuration, flow stability phenomenon and the main problems of a windowed design for pressurized receivers. © 2011 Elsevier Ltd. Source


Crespo-Anadon J.I.,CIEMAT
Nuclear and Particle Physics Proceedings | Year: 2015

The latest results from the Double Chooz experiment on the neutrino mixing angle θ13 are presented. A detector located at an average distance of 1050 m from the two reactor cores of the Chooz nuclear power plant has accumulated a live time of 467.90 days, corresponding to an exposure of 66.5 GW-ton-year (reactor power × detector mass × live time). A revised analysis has boosted the signal efficiency and reduced the backgrounds and systematic uncertainties compared to previous publications, paving the way for the two detector phase. The measured sin22θ13 = 0.090-0.029 +0.032 is extracted from a fit to the energy spectrum. A deviation from the prediction above a visible energy of 4 MeV is found, being consistent with an unaccounted reactor flux effect, which does not affect the θ13 result. A consistent value of θ13 is measured in a rate-only fit to the number of observed candidates as a function of the reactor power, confirming the robustness of the result. © 2015 Elsevier B.V. Source

Discover hidden collaborations