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    A new Agency to manage Britain's commitment to biofuels was established today by Transport Secretary Ruth Kelly. The Renewable Fuels Agency will be responsible for the day to day running of the Renewable Transport Fuels Obligation, coming into force in April next year. By 2010, the Obligation will mean that 5% of all the fuels sold in the UK should come from biofuels, which could save 2.6m to 3m tonnes of carbon dioxide a year. eGov Monitor - November 5, 2007.

    Prices for prompt loading South African coal cargoes reached a new record last week with a trade at $85.00 a tonne free-on-board (FOB) for a February cargo. Strong Indian demand and tight supply has pushed South African prices up to record levels from around $47.00 at the beginning of the year. European DES/CIF ARA coal prices have remained fairly stable over the past few days, having traded up to a record $130.00 a tonne DES ARA late last week. Fair value is probably just below $130.00 a tonne, traders said. At this price, some forms of biomass become directly competitive with coal. Reuters Africa - November 4, 2007.

    The government of India's Harayana state has decided to promote biomass power projects based on gasification in a move to help rural communities replace costly diesel and furnace oil. The news was announced during a meeting of the Haryana Renewable Energy Development Agency (HAREDA). Six pilot plants have demonstrated the efficiency and practicability of small-scale biomass gasification. Capital subsidies will now be made available to similar projects at the rate of Rs 2.5 lakh (€4400) per 100 KW for electrical applications and Rs 2 lakh (€3500) per 300 KW for thermal applications. New Kerala - November 1, 2007.

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Monday, November 05, 2007

Black carbon from fossil fuels heats the planet, soot from biomass cools it

Black carbon contained in soot from the combustion of fossil fuels may be responsible for around 16% of the gross warming of the planet. According to testimony provided by five scientists before the US House Committee on Oversight and Government Reform, it may be the second-most significant global warming pollutant after carbon dioxide and ahead of methane.

The black carbon in soot performs its warming by absorbing sunlight, converting it into infrared (heat) radiation, and emitting that heat radiation to the air around it. Soot on the surface of snow and sea ice contribute to both the melting of those surfaces as well as the warming of the air (earlier post).

But according to the scientists, particles from burning biomass are less oily and contain a much lower black carbon fraction than fossil fuel soot particles. Biomass-burning particles thus tend to cool climate on a global scale. This results in the so-called 'global dimming' effect.

Testifying before the committee were:
  • Dr. Mark Z. Jacobson, Prof. of Civil and Environmental Engineering, Atmosphere/Energy Program, Stanford University
  • Dr. Tami C. Bond, Asst. Prof. of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign
  • Dr. V. Ramanathan, Prof. of Climate and Atmospheric Sciences, Scripps Institute of Oceanography, University of San Diego
  • Dr. Charles Zender, Assoc. Prof. of Earth System Science, University of California at Irvine.
  • Dr. Joel Schwartz, Professor of Environmental Epidemiology, Harvard University
Because of the relatively short lifetime of soot in the atmosphere compared to greenhouse gases, control of soot may be the fastest method of slowing warming for a specific period, according to Dr. Jacobson.

Black carbon, noted Dr. Bond, adds 2-3 order of magnitude more energy to the climate system than an equivalent mass of CO2 because black carbon is an extremely good absorber of visible light. While carbon dioxide stays in the atmosphere for decades, it absorbs just a small amount of infrared radiation:

The findings have implications for the use of diesel fuel. Because of their increased fuel efficiency relative to gasoline vehicles, diesels are seen as an improvement over gasoline with respect to global warming issues. However, once soot warming is factored in, the difference between the two platforms is greatly reduced, as diesel emits more soot than gasoline:
:: :: :: :: :: :: :: :: :: ::

Methods proposed to control fuel soot include improving engines; switching fuels; adding particle traps; and changing vehicle technologies.
In sum, there is not an advantage and a potential disadvantage of diesel versus gasoline in terms of climate and air pollution impact. However, neither type of vehicle is satisfactory or useful for solving climate and health problems as the emissions from both are very high. Even modest improvements in mileage standards for all vehicles are beneficial, but will only delay the eventual increase in emissions due to a larger population. — Dr. Jacobson
The scientists therefor advise a conversion of vehicles from fossil fuels to electric, plug-in hybrid or hydrogen fuel cell vehicles, where the electricity or hydrogen is produced by a renewable energy sources.

The good new is that, given the fact that biomass particles may help cool the planet, their use in dedicated power plants would become a viable strategy to fight global warming. Moreover, unlike any of the conventional renewables (wind, solar, geothermal, etc...) biomass can be used in carbon-negative energy systems.

The overall effect of biomass used in so-called 'bio-energy with carbon storage' (BECS) systems on reducing global warming, can thus become even larger than first predicted.

Image: Map showing the annual mean temperature change due to dirty snow in degrees Celsius.

U.S. House, Committee on Oversight and Government Reform: Hearing Examines Black Carbon and Global Warming - October 18, 2007

GreenCarCongress: Black Carbon May be Second-Most Significant Global Warming Pollutant After Carbon Dioxide; Alters Picture of Diesel Engine Benefits - November 5, 2007.

Biopact: Dirty snow may warm Arctic as much as greenhouse gases - cleaner fuels needed - June 06, 2007


David B. Benson said...

As I read Professor Jacobson's report, while biomass burning (forest fires) might help cool, black carbon, whether from fossil diesel or biodiesel, certainly helps to warm the planet.

So I fear that burning biofuels in 'dedicated power plants', while carbon-neutral, will still produce harmful black carbon soot (unless somehow scrubbed out).

[Otherwise, this was another of Biopact's ueful summaries, although rather discouraging reading with regard to the world's ocean fleet.]

11:12 PM  

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