Twenty-nine states and the District of Columbia now have renewable electricity mandates. President Obama and several members of Congress have supported one at the federal level. Polls routinely show strong support among voters for renewable energy projects — as long as they don’t cost too much.

But there’s the rub: while energy sources like sunlight and wind are free and naturally replenished, converting them into large quantities of electricity requires vast amounts of natural resources — most notably, land. Even a cursory look at these costs exposes the deep contradictions in the renewable energy movement.

Consider California’s new mandate. The state’s peak electricity demand is about 52,000 megawatts. Meeting the one-third target will require (if you oversimplify a bit) about 17,000 megawatts of renewable energy capacity. Let’s assume that California will get half of that capacity from solar and half from wind. Most of its large-scale solar electricity production will presumably come from projects like the $2 billion Ivanpah solar plant, which is now under construction in the Mojave Desert in southern California. When completed, Ivanpah, which aims to provide 370 megawatts of solar generation capacity, will cover 3,600 acres — about five and a half square miles.

The math is simple: to have 8,500 megawatts of solar capacity, California would need at least 23 projects the size of Ivanpah, covering about 129 square miles, an area more than five times as large as Manhattan. While there’s plenty of land in the Mojave, projects as big as Ivanpah raise environmental concerns. In April, the federal Bureau of Land Management ordered a halt to construction on part of the facility out of concern for the desert tortoise, which is protected under the Endangered Species Act.

Wind energy projects require even more land. The Roscoe wind farm in Texas, which has a capacity of 781.5 megawatts, covers about 154 square miles. Again, the math is straightforward: to have 8,500 megawatts of wind generation capacity, California would likely need to set aside an area equivalent to more than 70 Manhattans. Apart from the impact on the environment itself, few if any people could live on the land because of the noise (and the infrasound, which is inaudible to most humans but potentially harmful) produced by the turbines.

Industrial solar and wind projects also require long swaths of land for power lines. Last year, despite opposition from environmental groups, San Diego Gas & Electric started construction on the 117-mile Sunrise Powerlink, which will carry electricity from solar, wind and geothermal projects located in Imperial County, Calif., to customers in and around San Diego. In January, environmental groups filed a federal lawsuit to prevent the $1.9 billion line from cutting through a nearby national forest.

Not all environmentalists ignore renewable energy’s land requirements. The Nature Conservancy has coined the term “energy sprawl” to describe it. Unfortunately, energy sprawl is only one of the ways that renewable energy makes heavy demands on natural resources.

Consider the massive quantities of steel required for wind projects. The production and transportation of steel are both expensive and energy-intensive, and installing a single wind turbine requires about 200 tons of it. Many turbines have capacities of 3 or 4 megawatts, so you can assume that each megawatt of wind capacity requires roughly 50 tons of steel. By contrast, a typical natural gas turbine can produce nearly 43 megawatts while weighing only 9 tons. Thus, each megawatt of capacity requires less than a quarter of a ton of steel.

Obviously these are ballpark figures, but however you crunch the numbers, the takeaway is the same: the amount of steel needed to generate a given amount of electricity from a wind turbine is greater by several orders of magnitude.

Such profligate use of resources is the antithesis of the environmental ideal. Nearly four decades ago, the economist E. F. Schumacher distilled the essence of environmental protection down to three words: “Small is beautiful.” In the rush to do something — anything — to deal with the intractable problem of greenhouse gas emissions, environmental groups and policy makers have determined that renewable energy is the answer. But in doing so they’ve tossed Schumacher’s dictum into the ditch.

All energy and power systems exact a toll. If we are to take Schumacher’s phrase to heart while also reducing the rate of growth of greenhouse gas emissions, we must exploit the low-carbon energy sources — natural gas and, yes, nuclear — that have smaller footprints.

Source: www.nytimes.com

Former Mayor Gavin Newsom said of their program: “GoSolarSF has more than doubled the number of solar installations in our City and created dozens of jobs. This program is literally transforming how our homes and businesses generate and consume electricity rooftop by rooftop.” (Source: getsolar.com)

Actually, it was Newsom who first put forth the goal of 100 percent renewable energy in San Francisco by 2020. One source said that in 2006, San Francisco was only at about 12 percent renewable energy, and that rate put them easily in the top ten U.S. cities for clean energy. Currently San Francisco receives a significant amount of its electricity from the Hetch Hetchy hydroelectric powerplant. It was recently reported that the city had failed to find a competitor to their main supplier, Pacific Gas and Electricity, who can deliver power from 51 percent renewable sources.

Some say the 100 percent renewable goal by 2020 is not feasible, but the director of the city’s Environment Department said the city had actually exceeded their very ambitious recycling goal of 75 percent diversion from the waste stream, so a very aggressive energy goal might be beneficial.

Source: www.care2.com

Una mejor utilización de la combinación del poder solar y el poder eólico, junto con una manera de almacenar la energía sobrante, podría aumentar el uso de la energía renovable en California, Texas y todas partes de EE.UU., según un estudio por ingeniero agrícola Brian Vick con la Unidad de Investigación de Energía Renovable y Manejo de Estiércol mantenida por el ARS en Bushland, Texas. ARS es la agencia principal de investigaciones científicas del Departamento de Agricultura de EE.UU. (USDA por sus siglas en inglés).

Vick descubrió que en la región del Panhandle de Texas y la parte occidental de Texas, así como en California, hay una desigualdad casi exacta entre la producción de energía eólica y el mayor consumo de energía durante un período de 24 horas. En estos sitios, a la altura de las turbinas eólicas modernas, la fuerza del viento es la más baja al mediodía, cuando el mayor consumo de energía ocurre. En Texas, también hay una desigualdad estacional: El viento es el mas débil durante el verano, cuando el major consumo de energía ocurre.

Pero los rayos del sol son los más fuertes al mediodía y durante el verano.

Texas es el primero estado en EE.UU. para la producción de electricidad generada del viento, con Iowa como el segundo y California como el tercero. California es el líder en producción de electricidad generada del sol.

El sistema más eficaz de almacenaje de energía se usa en las plantas de energía solar térmica, donde se usa el calor del sol para calentar agua y otros fluidos. Los fluidos se mantienen calientes después de la puesta del sol, listas para utilización en la producción de vapor para generar electricidad.

La electricidad sobrante generada por el viento durante la noche y muy temprana en la mañana se puede almacenar en la red de tendido eléctrico para utilización por instalaciones tales como aquellas de almacenamiento de hidroelectricidad o de energía de aire comprimido para satisfacer las demandas de consumo durante el día.

Vick y sus colegas en Bushland han probado y ayudado a diseñar turbinas eólicas y sistemas híbridos de energía solar y eólica para utilización en sitios fuera de la red de tendido eléctrico, sitios residenciales, y granjas eólicas para el Departamento de Energía de EE.UU. También han diseñado y probado sistemas híbridos de energía solar y eólica para tendidos eléctricos simulados en sitios remotos tales como pueblos pescadores en Alaska.

Durante la conferencia este año de la Asociación Americana de Energía Eólica en Dallas, Texas, Vick informó sobre los resultados de combinar las granjas eólicas con plantas de energía solar térmica, incluyendo almacenaje de energía para los estados de Arizona, Colorado, Nevada, Nuevo Mexico y Utah.

Esta investigación apoya la prioridad del USDA de promover el desarrollo de nuevas fuentes de energía alternativa.

Fuente: www.ars.usda.gov

(Fuente: www.abc.es) La comunidad científica y política de Estados Unidos ha celebrado la entrada en funcionamiento en California del mayor láser del mundo, capaz de emular la intensidad energética de una estrella.
El Gobernador de California, Arnold Schwarzenegger, y el Secretario de Energía, Steven Chu, entre otros, participaron el viernes en San Francisco en la presentación del llamado National Ignition Facility (NIF), un láser formado por 192 haces de luz, y con capacidad para lograr la ansiada fusión nuclear.
La fusión nuclear, que se ha mostrado esquiva a la comunidad científica durante décadas, permite liberar cantidades ingentes de energía, con un consumo muy escaso, además de contar con otras ventajas, como producir menos radiactividad que la energía nuclear.
Hasta ahora, la fusión nuclear requería grandes cantidades de energía para desencadenarse, y solo se había logrado mediante las bombas nucleares, de ahí la importancia del nuevo láser.
Explosión termonuclear del tamaño de un guisante
En la presentación el viernes del NIF, que tiene el tamaño de un estadio, se explicó el potencial del aparato, mediante un experimento que consiste en dirigir los 192 haces de luz hacia una pequeña esfera del tamaño de un guisante, rellena de hidrógeno.
El objetivo es crear en el interior de la esfera una pequeña explosión termonuclear, en la que se alcanzarían temperaturas de 100 millones de grados, como en el interior de una estrella.
Durante una fracción de segundo, se puede liberar en la miniexplosión una cantidad de energía tan poderosa como para alumbrar a todo el país, dijo a la Cadena Fox el director del programa Ed Moses.
Una fusión nuclear de este tipo no se había conseguido hasta ahora en la Tierra, si bien los críticos consideran que la construcción del láser, en el que se han invertido 3.500 millones de dólares, es excesivo.
Sin embargo, los responsables del centro consideran que el láser permitirá devolver con creces el dinero invertido de los contribuyentes. De hecho, el NIF ha producido ya 25 veces más energía que otros sistemas de láser existentes, y cuenta con capacidad para mantener encendidas 10.000 bombillas por segundo.

The US government is putting a hold on new solar energy projects on public land for two years so it can study the environmental impact of sun-driven plants.

The Bureau of Land Management says the moratorium on solar proposals is needed to determine how a new generation of large-scale projects could affect plants and wildlife on the land it manages.

The move has angered some solar energy proponents who argue it could hold up the industry at a vital juncture, given the pressing need to secure alternative energy sources at a time of soaring oil prices. “This technology has been around for nearly three decades.

If there is an environmental concern, that can be addressed without putting a halt to this technology and helping to impact our greenhouse gas emissions and the environmental degradation from coal-fired and natural gas plants,” said Brad Collins, executive director of the American Solar Energy Society.

He said the review appeared to be an arbitrary “road block” that contradicted “the stated goals of both presidential candidates, the stated goals of Congress and the American public.” The Bureau of Land Management, which looks after 258 million acres of federal land, much of it flat, sun-baked terrain in the western US considered ideal for solar energy development, says the study is required by law and backed by environmental groups.

“Obviously the footprint from solar development is significant,” said Celia Boddington, a BLM spokeswoman.

“(The solar plants) cover thousands of acres potentially, and we need to determine what the environmental consequences are of that, look at what it means when you spray the land with herbicides or remove vegetation.” She said the BLM’s solar programme was “completely new” and required a framework to be established.

The environmental assessment was being “fast-tracked”. During the study, the BLM will not accept any new applications to lease public land for solar developments. But it insists it is “not holding industry up” and will continue to process 150 existing applications for roughly one million acres of federal land considered to have the best potential for solar development.

Together the proposed projects could produce as much as 70 billion watts of electricity, enough energy to power 20 million homes. Most of the applications were received during the past year and a half, Ms Boddington said.

“So it’s still very, very new. The potential is there but we want to make sure we do it properly because the environmental impacts are potentially significant. This is exciting, it’s a great opportunity but solar development has not yet been established commercially on a large scale.”

Mr Collins argued the analysis could halt recent momentum in the domestic solar industry that has seen “a large number of international, large-scale players move their operations and headquarters” to the US and impact the growing field of “green collar jobs”.

“It would be an example of taking a new industry and arbitrarily placing road blocks in the way to a transition to the safe, sustainable energy economy that everybody says they want.”