CALDEIRÃO DE BOLSA

noralis Escreveu:Há aqui uns raciocínios que não batem certo!

Os biocombustíveis não vizam reduzir o chamado aquecimento global mas serem uma alternativa ao petróleo pois mais cedo ou mais tarde este ira "acabar"!

No entanto trazem outros problemas...desflorestação para monoculturas...inflação dos preços do alimentos, etc, etc

September 26, 2007

RETHINKING RENEWABLES
Biofuels 'Emit More Greenhouse Gases than Fossil Fuels'

A team of researchers led by Nobel-prize winning chemist Paul Crutzen has found that growing and using biofuels emits up to 70 percent more greenhouse gases than fossil fuels. They are warning that the cure could end up being worse than the disease.

Biofuels, once championed as the great hope for fighting climate change, could end up being more damaging to the environment than oil or gasoline. A new study has found that the growth and use of crops to make biofuels produces more damaging greenhouse gases than previously thought.

German Nobel-prize winning chemist Paul Crutzen and his team of researchers have calculated the emissions released by the growth and burning of crops such as maize, rapeseed and cane sugar to produce biofuels. The team of American, British and German scientists has found that the process releases twice as much nitrous oxide (N2O) as previously thought. They estimate that 3 to 5 percent of nitrogen in fertilizer is converted and emitted, as opposed to the 2 percent used by the Intergovernmental Panel on Climate Change (IPCC) in its calculations.

Crutzen is widely respected in the field of climate research, having received the Nobel Prize in 1995 for his research into the ozone layer. The study, published in the scientific journal Atmospheric Chemistry and Physics, finds that the growth and use of biofuels produced from rapeseed and maize can produce 70 percent and 50 percent more greenhouse gases respectively than fossil fuels.

"One wants rational decisions rather than simply jumping on the bandwagon because superficially something appears to reduce emissions," Keith Smith, a professor at the University of Edinburgh and co-author of the study, told the London Times.

The findings come in the wake of an OECD report earlier this month, which warned against rushing to grow reneweable energy crops because they cause food shortages and damage biodiversity while producing limited benefits.

The growth of corn for ethanol in the United States has already overtaken its cultivation for food, while in Europe the main biofuel crop is rapeseed.

http://www.spiegel.de/international/eur ... 89,00.html

Trend Escreveu:No JN li um artigo que refere que biocombustiveis implica um gasto de água (rega) e tal vai contribuir para sua escassez...etc.
Concluiam dizendo que biocombustiveis trazem mais problemas que soluçoes.

só se deve avançar .... quando a margem de segurança for superior a 99,9%.

Não se pode por o lucro à frente da humanidade!

Mas olha que o Fidel ("el coma andante") ainda não morreu. Já começaram a embalsamá-lo mas de baixo para cima.

Food FightThe case for turning crops into fuel.
By William Saletan
Posted Saturday, July 7, 2007, at 7:32 AM ET

Just when you thought George W. Bush and Fidel Castro were dead—one politically, the other literally—they're back at it. Their new fight is about biofuel, the conversion of living things into liquid energy. One president says it's an assault on nature and humanity. The other says it's an agricultural revolution that will liberate the masses. Bush is the revolutionary. Castro is the reactionary.

Bush has been evangelizing for biofuel since he lost control of Congress last year. Castro has been attacking it since he returned from surgery this spring. "Transforming food into fuels is a monstrosity," Castro wrote two months ago in a series of angry essays. He said it would devour the world's food supply, "killing the poor masses through hunger."

Castro's argument has gained widespread support. The Economist declared (subscription required) that "Castro was right" and faulted Bush's "unhealthy enthusiasm for ethanol." Foreign Affairs published a long article titled, "How Biofuels Could Starve the Poor." On July 4, the U.N. Food and Agriculture Organization and the Organization for Economic Cooperation and Development warned that "increased demand for bio-fuels … could drive up world prices for many farm products." In a visit to Havana, the director of the U.N. Environment Program echoed Castro's concerns.

The critics are right about several things. Corn-based ethanol isn't very economical or environmentally helpful. It inflates food prices, and it's propped up by foolish subsidies and tariffs. But to write off biofuel is to miss the forest for the trees—or, in this case, the grassland for the corn. Enthusiasm for ethanol isn't the problem. It's the solution.

Biofuel is our next logical technology. We've had an agricultural revolution, an industrial revolution, and an information technology revolution. Now, we're putting them together to harness the power of life. Ecologically, it's ideal: a fuel that literally grows on trees.

But biofuel has aroused the same fears as free trade, with a twist. The argument against free trade was that people in poor countries would underbid and take jobs from people in rich countries. The argument against biofuel is that people in rich countries will outbid and take food from people in poor countries. The old buzzword was job security. The new buzzword is "food security."

What critics of free trade forget is that people in rich countries aren't just producers; they're consumers: Competition from poor countries drives down wages but compensates by lowering prices. Conversely, what critics of biofuel forget is that people in poor countries aren't just consumers; they're producers. Crop purchases by rich countries drive up prices but compensate by driving up incomes. Castro says turning food into fuel is a "waste," but that's not true. Fuel helps make food available and affordable.

Castro thinks the very idea of making fuel from food is "diabolical." But using food for fuel wasn't Satan's idea. It was God's. Fuel is the whole point of food. That's why edible crops such as corn and cassava are also easy ethanol sources: They're loaded with energy-bearing starch.

Biofuel doesn't feed people directly. But we've been diverting food from direct human consumption since we domesticated animals. Most of the corn we export today feeds livestock, not people. Two months ago, a U.N. report calculated that one-third of the increased demand for food over the next 30 years will come from people shifting their eating habits to meat and dairy—a net loss of dietary efficiency—as they become able to afford it. I don't see Castro complaining about that diversion. In fact, he worries that biofuel is taking land from "producers of beef cattle." Evidently, he's suffering an irony deficiency.

Castro says Bush insists that biofuels "must be extracted from foods." That's false. Bush points out that corn is an inefficient ethanol source. In its place, Bush touts sugar cane, wood chips, and switchgrass. Such "cellulosic" ethanol could lower the output of greenhouse gases and deliver up to six times as much energy as its production requires.

If you want to help poor people, biofuel beats the heck out of oil. In a biofuel economy, the chief asset is open land. Who has open land? Poor countries. Latin America has sugar cane. Africa and Asia have cassava. Switchgrass, which grows in dry regions, will level the playing field further. Bush says switchgrass will empower the Western United States. That's nice, but the real story is that it'll empower the Southern Hemisphere.

What makes Castro and other radicals so conservative about biofuel? The same thing that troubles Bush about human embryo research: the industrialization of biology. For the right, the chief concern is humanity. For the left, it's nature. That's why Castro worries that genetic crop modifications by ethanol conglomerates will unleash "transgenetic contamination" and put "food production at risk."

True, biotechnology can go wrong. But it can also go wonderfully right. Scientists are learning to split corn so it can make ethanol and still feed animals. We're studying the use of microbes to extract fuel from straw and wood waste. We're trying to grow biofuel in algae. We're even learning to make fuel from animal fat and excrement.

Yes, ethanol subsidies are a scam. Yes, we should drop our trade barriers and let Brazilian sugar cane wipe out American corn. Yes, we need solar power, conservation, and efficiency. But don't give up on biofuel. It just needs time to grow.

Investigação publicada na revista “Science”
Estudo: reflorestação faz melhor ao clima do que os biocombustíveis
17.08.2007 - 22h54 AFP

A quantidade de dióxido de carbono sequestrado pela reflorestação é maior do que as emissões evitadas pelo uso de biocombustíveis, constata um estudo publicado hoje na revista “Science” sobre as estratégias de mitigação deste gás com efeito de estufa e um dos causadores do sobre-aquecimento do planeta.

Num período de 30 anos, a reflorestação permite capturar entre duas e nove vezes mais dióxido de carbono do que as emissões deste gás que seriam economizadas pela utilização de biocombustíveis, concluíram Renton Righelato, do World Land Trust (organização de conservação dos ecossistemas) e Dominick Spracklen, da Universidade de Leeds, no Reino Unido.

Na luta contra o sobre-aquecimento do planeta, “os responsáveis políticos fariam melhor, a curto prazo (30 anos) em concentrar-se na melhoria da eficiência energética dos combustíveis fósseis, na conservação e na recuperação das florestas em terrenos que não são necessários à alimentação”, escrevem os autores deste estudo.

Ao absorver o dióxido de carbono necessário ao seu crescimento, a vegetação e as árvores actuam como “sumidouros de carbono” da atmosfera.

Os combustíveis “verdes” são defendidos para substituir as fontes fósseis (petróleo, carvão e gás natural) e assim reduzir as emissões de dióxido de carbono.