Archive for the ‘biofuels’ Category
|The promise and perils of algae-based biofuels
Monday, December 28th, 2009
In a forthcoming article1 in Trends in Ecology and Evolution, Val Smith and colleagues describe why biofuels produced from algae have many benefits:
- The current production of biodiesel (~2 billion gallons in 2006) is far lower than annual consumption of diesel fuel (44 billion gallons per year). Simply put, biodiesel crops can’t keep pace with demand. We would have to grow significantly more biofuel crops, which would affect land use by reducing the acreage of food crops or natural habitats.
- Algae fats (lipids) can serve as the feedstocks for many types of fuels, including aviation fuel, which would be a major benefit because airline travel is a huge part of most people’s carbon footprints. Algae fuels are potentially carbon neutral. Making air travel carbon neutral would be a game changer.
- Algae grow extremely fast—much faster than terrestrial plants (which are made into biodiesel or ethanol). They lack anatomical parts like roots, flowers, and woody stems that don’t help plants photosynthesize (making them more productive than plants).
- One of the most amazing statistics in this paper is how much less land it would take to make algae based fuels compared to terrestrial plants because of the increased productivity of algae. To produce an amount of fuel equivalent to the global demand for oil, we would only need an area of land equivalent to 3-20% of current croplands. If we were to use biofuel plant crops instead, we would need about 2-8 times the amount of current global cropland. That’s so amazing I did a double take when I read it.
- Algae can be grown in tanks on lands that are marginally useful for crops so that we don’t have to sacrifice croplands.
- They can serve double-duty by removing excess nutrients from wastewater, thereby linking energy production and wastewater treatment.
- Algal production virtually eliminates the use of herbicides and insecticides and uses much less water than growing crops for fuels.
They also point out an interesting pitfall:
- Bioreactors containing algae are often unintentionally invaded by zooplankton that eat the algae. This can lead to predator-prey-type cycles in algae biomass, which is not good when you want to maximize algal biomass production.
- The solution? Add fish that eat the zooplankton. This would cause “top-down” pressure on the zooplankton, keeping their populations in check.
1Smith, V. et al (in press) The ecology of algal biodiesel production. Trends in Ecology and Evolution.
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Photo credit: http://www.flickr.com/photos/sandialabs/ / CC BY-NC-SA 2.0
Posted in biofuels, energy, solutions, sustainability, technology | 3 Comments »
If we switch to biofuels, how much do indirect greenhouse gas emissions matter?
Saturday, December 5th, 2009
In this week’s issue of Science, Jerry Melillo and colleagues investigate1 what kinds of impacts might arise from changing land use to grow more cellulosic biofuel crops. If you think about it, the switch to biofuels could have a big impact on greenhouse gas emissions—and not in a good way. For instance, clearing a forest or pastureland to grow a biofuel crop could cause a net release of carbon from the ecosystem, as plant growth changes, biomass is lost, and soil decomposition increases.
Using a model of the world economy coupled to a terrestrial ecosystem model, they considered two cases:
- Case 1: Natural lands (e.g., forests and pastures) are allowed to be converted to meet increasing biofuel demand.
- Case 2: Existing managed lands are managed even more intensely to generate biofuel demand.
What did they find?
Posted in biofuels, technology | No Comments »
How our foods and fuels drive poor air quality in the tropics
Friday, October 23rd, 2009
Palm oil has garnered a lot of news recently. It’s an ingredient in many processed foods and, increasingly, is being used to make biodiesel fuel.
One initial concern was the destruction of tropical rainforests and peatlands to create palm oil plantations. To the extent that these plantations are leading to habitat destruction in places like Indonesia, this threatens species like the orangutan.
In this week’s early edition of the Proceedings of the National Academy of Sciences (open access), a team addressed a second potential problem: air pollution, specifically ground-level ozone production.
The news about ozone is potentially confusing, so let me start with a quick primer:
- Ozone’s chemical formula is O3, which is similar to oxygen we breathe in the air (O2).
- Ozone is a highly oxidizing molecule, which means that it is harmful to living organisms when it comes in contact with them (such as when we inhale it). If you have ever been around electrical motors and you smell a pungent odor, that’s ozone.
- Ozone in the stratosphere (upper atmosphere) is good for life on Earth. It absorbs ultraviolet light and prevents us from getting skin cancer. This is the ozone that gets damaged by CFCs and other gases, creating the ozone hole over Antarctica. Because we do not come into contact with this ozone, we benefit from it’s sunscreen properties without suffering any ill health effects.
- Ozone in the troposphere (the part of the atmosphere near the ground, so it’s also called “ground-level” ozone), however, is not a good thing to have around because this is the part of the atmosphere that comes in contact with living organisms.
- Ground-level ozone is often a byproduct of urban sprawl. It forms when volatile organic carbon (VOC) from vehicles (think gasoline vapor) and vegetation (think the smell of Christmas trees) react with nitric oxides from car exhaust under warm, sunny conditions.
- It’s a part of the chemical soup we call smog. This is why we often see code orange or code red days in metro suburban areas like Washington DC, suburban NY, Atlanta, and Raleigh-Durham, NC warning people with respiratory illnesses, children, and the elderly to stay inside.
- Although there is reason to believe that increasing ozone is connected with the rising incidence of asthma, that link has not been well established.
- The World Health Organization has recommended exposure limits of no more than 50 parts per billion in any 8 hour period.
The PNAS article indicates that ozone production is a growing threat in palm plantations, which show higher temperatures and levels of VOCs and nitric oxides than adjacent rainforests.
Although the level of ozone in palm plantations is not yet at a level that threatens health, the team used a model of ozone production to suggest that if nitric oxide emissions were to reach levels seen in the developed Western world (which may be expected with further development and auto use), this could lead to ozone concentrations exceeding 100 ppb, which is considered an emergency air quality event.
Bottom line: In tropical regions, we need to think of how to balance economic development, biofuel production, habitat protection, and–now– human health. To the extent that processed foods and biofuel production are driven largely by consumption in industrialized countries, we share in the responsibility of dealing with this issue.
Already, some companies like Whole Foods have banned unsustainably produced palm oil to combat habitat destruction, but this doesn’t solve the new issue of air pollution. The article suggests that new varieties of palm plants that emit much lower amounts of VOCs could solve this problem. That’s good news.
Photo credit: http://www.flickr.com/photos/ahvega/ / CC BY 2.0
Tags: Indonesia, orangutan, ozone, palm oil
Posted in biofuels, pollutants | 1 Comment »
In this week’s Science: Fixing a major flaw with biofuels
Thursday, October 22nd, 2009
There’s an interesting article in Friday’s issue of Science by a team of ecologists and environmental scientists arguing that the way we think about biofuels is flawed and can potentially lead to bad outcomes in mitigating climate change.
Here’ s the issue: When we think of using, say, wood from forests or grasses from grasslands for energy, we normally think of this process as being carbon neutral–i.e., the carbon released when we burn the wood/grass will be taken back up by the regenerating forest/grassland. No net change in atmospheric CO2. At face value, this sounds like a great strategy for dealing with atmospheric CO2.
However, the authors indicate that the carbon accounting system in the Kyoto protocol, EU carbon trading system, and developing U.S. cap and trade plans makes a mistake in how biofuels are handled. Specifically, because of the carbon neutrality of biofuels, the carbon accounting system simply ignores (1) the release of carbon to the atmosphere from biofuel burning and (2) the movement of carbon from the atmosphere back into regenerating forests and grasslands (or other biofuel crop). At first glance, this appears to make sense: If burning biofuels is carbon neutral, just ignore the release and uptake of carbon since they cancel one another out.
There are two major problems with this–one ecological and another economic:
Tags: biofuel, carbon neutral
Posted in biofuels, climate change science | 2 Comments »
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