Fuel from algae scum (instead of corn) [CNN Video]

[sinimod]

A while back, I posted this in the thread "What about algae derived biofuel?" in the Contributions and Suggestions forum of the Front Desk forum. However, I think the thoughts Dr. Michael Briggs, University of New Hampshire, Physics Department (2004) has expressed are very interesting and I hope more people will read them. So I thought it appropriate to post them here too:

The Department of Energy says we use about 60 billion gallons of petroleum diesel each year and about 120 billion gallons of gasoline. Spark ignition engines, which use gasoline, are generally about 35-40% less efficient than compression-ignition engines, or diesel. So if spark ignition engines are gradually replaced with compression-ignition engines, that would decrease the amount of petroleum needed to about 78 billion gallons per year. Combine that with the approximately 60 billion gallons currently used for diesel and you get about 138 billion gallons of petroleum needed in the US on an annual basis.

Now, biodiesel is about 5-8% less energy dense than petroleum diesel, but its greater lubricity and more complete combustion offset that somewhat, leading to an overall fuel efficiency about 2% less than petroleum diesel. So, we’d need about 2% more than that 138 billion gallons, or 140.8 billion gallons of biodiesel. Hybrid technology for transportation could cut that figure considerably.

Biodiesel can be used in existing diesel engines without modification, and can be blended in at any ratio with petroleum diesel, eliminating the ’chicken and egg’ dilemma that other alternative fuels have (hydrogen, for example). With biodiesel, since the same engines can run on conventional petroleum diesel, manufacturers can comfortably produce diesel vehicles before biodiesel is available on a wide scale.

One of the important concerns about wide-scale development of biodiesel is if it would displace croplands currently used for food crops. In the US, roughly 450 million acres of land is used for growing crops, with the majority of that actually being used for producing animal feed for the meat industry. Another 580 million acres is used for grassland pasture and range, according to the USDA’s Economic Research Service. This accounts for nearly half of the 2.3 billion acres within the US (only 3% of which, or 66 million acres, is categorized as urban land). For any biofuel to succeed at replacing a large quantity of petroleum, the yield of fuel per acre needs to be as high as possible. At heart, biofuels are a form of solar energy, as plants use photosynthesis to convert solar energy into chemical energy stored in the form of oils, carbohydrates, proteins, etc.. The more efficient a particular plant is at converting that solar energy into chemical energy, the better it is from a biofuels perspective. Among the most photosynthetically efficient plants are various types of algaes.

Some species of algae are ideally suited to biodiesel production due to their high oil content (some well over 50% oil), and extremely fast growth rates. From the results of the Aquatic Species Program, algae farms would let us supply enough biodiesel to completely replace petroleum as a transportation fuel in the US (as well as its other main use - home heating oil) - but we first have to solve a few of the problems they encountered along the way.

The National Renewable Energy Laboratory’s (NREL) research has shown that one quad (7.5 billion gallons) could be produced from 200, 000 hectares of desert land (200, 000 hectares is equivalent to 780 square miles, or roughly 500, 000 acres), if the remaining challenges are solved (they will, as several research groups and companies are working towards it).

The amount of land necessary 140.8 billion gallons of biodiesel per year of algal biodiesel works out to be about 15, 000 square miles. To put that in perspective, consider that the Sonora desert in the southwestern US comprises 120, 000 square miles. Enough biodiesel to replace all petroleum transportation fuels could be grown in 15, 000 square miles, or roughly 12.5 percent of the area of the Sonora desert (not advocating this, just using this as a hypothetical example). That 15, 000 square miles works out to roughly 9.5 million acres - far less than the 450 million acres currently used for crop farming in the US, and the over 500 million acres used as grazing land for farm animals.

Actually, it would be preferable to spread the algae production around the country, to lessen the cost and energy used in transporting the feedstocks. Algae farms could also be constructed to use waste streams (either human waste or animal waste from animal farms) as a food source, which would provide a beautiful way of spreading algae production around the country. Nutrients can also be extracted from the algae for the production of a fertilizer high in nitrogen and phosphorous. By using waste streams (agricultural, farm animal waste, and human sewage) as the nutrient source, these farms essentially also provide a means of recycling nutrients from fertilizer to food to waste and back to fertilizer. Extracting the nutrients from algae provides a far safer and cleaner method of doing this than spreading manure or wastewater treatment plant "bio-solids" on farmland.

Yields depend on sunlight levels. Spreading the algae production around the country would result in more land being required than the projected 9.5 million acres, but the benefits from distributed production would outweigh the larger land requirement. Further, these yield estimates are based on what is theoretically achievable - roughly 15, 000 gallons per acre-year. It’s important to point out that the DOE’s ASP that projected that such yields are possible, was never able to come close to achieving such yields. But, consider that even if we are only able to sustain an average yield of 5, 000 gallons per acre-year in algae systems spread across the US, the amount of land required would still only be 28.5 million acres - a mere fraction still of the total farmland area in the US.

In "The Controlled Eutrophication process: Using Microalgae for CO2 Utilization and Agircultural Fertilizer Recycling", the authors estimated a cost per hectare of $40, 000 for algal ponds. In their model, the algal ponds would be built around the Salton Sea (in the Sonora desert) feeding off of the agircultural waste streams that normally pollute the Salton Sea with over 10, 000 tons of nitrogen and phosphate fertilizers each year. The estimate is based on fairly large ponds, 8 hectares in size each. To be conservative (since their estimate is fairly optimistic), we’ll arbitrarily increase the cost per hectare by 100% as a margin of safety. That brings the cost per hectare to $80, 000. Ponds equivalent to their design could be built around the country, using wastewater streams (human, animal, and agricultural) as feed sources. We found that at NREL’s yield rates, 15, 000 square miles (3.85 million hectares) of algae ponds would be needed to replace all petroleum transportation fuels with biodiesel. At the cost of $80, 000 per hectare, that would work out to roughly $308 billion to build the farms.

The operating costs (including power consumption, labor, chemicals, and fixed capital costs (taxes, maintenance, insurance, depreciation, and return on investment) worked out to $12, 000 per hectare. That would equate to $46.2 billion per year for all the algae farms, to yield all the oil feedstock necessary for the entire country. Compare that to the $100-150 billion (my math calculates that at $50 per barrel, the US sends out $250 billion per year to foreign suppliers) the US spends each year just on purchasing crude oil from foreign countries, with all of that money leaving the US economy.

[gazelle]

Looks very promising. As with anything new, there are still a few problems to sort out.

One of the dangers I've heard about is the fear that the algae might escape into the waterways. I believe that Sri Lanka had this problem... Algae ponds were used to confuse pilots into thinking they saw a nice landing strip, only to sink into the lake. The algae is now a major nuisance.

Another problem was more tied into the idea of planting CO2-eating algae near coal power stations. If I remember the argument correctly, it was that the economics of it is self-defeating. The algae ponds add $x to the price of electricity, which make coal less attractive compared to "renewables". And eventually the coal power stations are shut down and the algae starve.
Well, I guess it's not such a problem if it means the coal power stations shut down!

In essence, though, I like the idea. We need to address all three pillars in managing climate destabilisation: mitigation, adaptation and reparation.
Society keeps extracting (at a growing rate) from the environment without giving anything back. We need to develop ways of transforming our waste back into something useful (such as mining our landfill, but that's another topic). Nature does a pretty good job of transforming, via trees and algae and bacteria. So let's use it!

[sinimod]

Stanford researchers find electrical current stemming from plants

http://www.eurekalert.org/pub_releas...-srf041310.php

In an electrifying first, Stanford scientists have plugged in to algae cells and harnessed a tiny electric current. They found it at the very source of energy production – photosynthesis, a plant's method of converting sunlight to chemical energy. It may be a first step toward generating "high efficiency" bioelectricity that doesn't give off carbon dioxide as a byproduct, the researchers say.

In this experiment, the researchers intercepted the electrons just after they had been excited by light and were at their highest energy levels. They placed the gold electrodes in the chloroplasts of algae cells, and siphoned off the electrons to generate the tiny electrical current.

Even though they are microscopic, the gold electrodes seem awfully expensive. Perhaps, with additional research, scientists will discover less expensive, readily available electrodes. At this point, this method of deriving electricity from algae does not seem economically feasible. However, if it can be developed, it could be a carbon free source of electricity.

[gazelle]

Originally Posted by sinimod

However, if it can be developed, it could be a carbon free source of electricity.

More than that, it may become more economically advantageous to plant trees rather than clear them! This could be a carbon-negative source of electricity. Very exciting.