
Algae has seemed like a great biofuel candidate because it's extremely efficent at creating energy from sunlight and it could potentially form closed loops for power plants - absorbing exhaust while creating new fuel - but a recent study has knocked algae off its pedestal.
University of Virginia researchers have found that the life cycle of algal biofuel produces high levels of greenhouse gas emissions -- much more than it sequesters.
The culprit is the large amount of fertilizer used to produce the algae. The fertilizers come from petroleum-bases sources and emit nitrous oxide. The researchers propose using fertilizer from sewage plants as a way around the problem.
It looks like we're still far away from an ideal biofuel, if there is one.
via Yale e360

written by Alessandro Machi, January 26, 2010
written by David Herron, January 26, 2010
written by gregg, January 26, 2010
If we eat, and then use our bodies to replace external motor devices, we should be efficient enough to survive, with the added bonus of being healthy
I know, not the coolest, hi-tech solution out there. But forgive me for trying to hit to birds with one stone. I mean, we're in an energy crisis and an obesity epidemic... So when I see stairs or an elevator I find all arrows pointing to the stairs.
I recently picked up a treadle sewing machine made back in 1915. In case someone doesn't know, a treadle is a foot powered device that uses the motion kind of like a calf machine at the gym to power some device.
The thing still works! Every moving part is accessible and can be cleaned with a rag and a little lubricant. I patched some pants and made curtains from used materials. How many computers have you seen that could provide any function after that kind of life? I mean, paperweights maybe, a museum too I suppose.
I guess I just feel like we might want to reevaluate how we got into this environmental mess in the first place, I think it was always our desire to captain the coolest forces in the universe without really knowing what we were getting into... So when the scale of our operations became too big the consequences of our non-perfection plan became visible- or catastrophic rather.
So is the answer to outsmart the laws of physics and defy entropy? I think most hi-tech plans can sound great but when they get tested on the scale of the solutions that we consider... the cracks open up.
I'm not saying never utilize technology, that would be foolish, but take it in stride, and don't buy the coolest thing right after it's created.
Maybe my attitude wouldn't have put a man on the moon by now, but then again we would have a healthy planet and wouldn't be considering making a moon colony to move too once the atmosphere has a run away greenhouse effect. To me the biggest drawback is that Gene Roddenberry isn't going to make a tv show about it, but I could deal with that if it meant a future for those who come after me.
written by Paul Kenjerski, January 26, 2010
written by ManDrake, January 26, 2010
written by Gordon, January 27, 2010
written by Jacob, January 27, 2010
written by Eamon Keane, January 27, 2010
You can get phosphorus from human urine and manure. Where do you think the phosphorus in this urine and manure comes from? It comes from mined phoshpate rock applied as fertilizer. Over half of manure is left on land and the nutrients are recycled by the soil so the cattle can graze the next year.
Now you could say, why not just collect the other half, and you have a point, although the logistics of it would be horrendous. Once you've collected it, you have the option of using it as manure for conventional crops, or using it for algae. Once you've collected it, do you just dump the manure into the carefully controlled algae open pond? Algae are finicky things which require the exact right ratio of NPK, the right temperature control, the right salinity, and the right level of sunlight if you want to get optimum growth. From the DOE Algae Biofuels Technology Roadmap (https://e-center.doe.gov/iips/faopor.nsf/UNID/79E3ABCACC9AC14A852575CA00799D99/$file/AlgalBiofuels_Roadmap_7.pdf):
"Additionally, careful control of nutrient levels is critical. Limitation of a key nutrient will 2566 have serious impacts on biomass productivity, but it may be desirable to use nutrient 2567 limitation (e.g., nitrogen, phosphorous, or silicon) as a means to induce oil accumulation 2568 in the cells (Sheehan et al., 199
. Too much of a particular nutrient may prove toxic." You could try to extract the nutrients from the manure, although if someone has found a way to do that, please provide me a link. Also tell me how much energy is expended to remove the nutrients.
So, to grow algae you have to have the intersection of:
A large CO2 source
A large area of worthless land
A large amount of manure
A large amount of worthless water
The right level of sunshine
You'll forgive me if I don't get too excited over algae. If you read the DOE's alage biofuel roadmap, you'll notice that there are no fewer than 15 energy inputs to get the final diesel from algae. You can get some energy from the leftover biomass. Here's a quote:
"Nonetheless, this analysis shows that any harvesting/extraction scheme involving dry algae is energy prohibitive, requiring at least 60% of the energy content of algae. There is thus a need to develop strains of algae with much higher energy content than available today."
These are the reasons you will never see a mention of life cycle analysis in an algae biofuel press release. Let's not blindly jump on the algae bandwagon like we did with ethanol.
written by Eamon Keane, January 27, 2010
http://seekingalpha.com/article/182522-taking-stock-of-phosphorus-and-biofuels
written by Casey Verdant, January 28, 2010
If you are interested in biofuels, check out this great website with hundreds of case studies on emerging green technologies and alternative energies: http://www.greencollareconomy.com It has the largest b2b green directory on the web and lots of sustainability white papers.
written by Carl Hage, January 28, 2010
The main problem is that they assume energy and water is used to make the CO2 injected into algae-- that is the biggest indirect cost. (Most prior algae projects did not inject external CO2.) Another large indirect expense is water and energy to make urea (N) and P2O5 fertilizer, though this is still less energy than the output (just like for corn). Indirect costs of extraction chemicals are not defined in the supporting material, but cost-effective extraction is a problem being solved by the new algae startups. Other options for fertilization are possible (recycling or wastewater).
Another big problem comparing algae vs corn vs switchgrass is that the energy compared is the HHV of the whole biomass and excludes water and energy to convert the biomass to usable fuel. For current corn ethanol, fermentation and distillation is the main consumption of indirect water and energy.
Actual operating energy assumed in the study is small-- only 3% of the algae energy output and could be met by solar panels above the paddlewheels. Water replacement for evaporation and extraction is less than San Diego rainfall over the ponds.
A possible source for fertilizer and CO2 is municipal sewage or farm runoff treatment plants, with recycled CO2 from biogas electric generators. The cancelled NREL Aquatic Species final report mentions the Sunnyvale, CA water treatment plant (where I live) which has 180ha algae ponds for final treatment (with no CO2 injection). The site generates power from landfill and digester gas. I calculated that the output of these generators would supply CO2 for 100ha of ponds. A dairy farm with biogas could use the same approach and generate algae biofuel on the side with no extra indirect water or energy. Right now cities and certain farms have to pay extra to treat water.
Note that some people (including this study) claim that algae sequesters CO2. No, it just recycles it to be released when burned or decomposed. Digging coal out of the ground, burning it, then feeding it to algae still releases fossil CO2 into the air. But biomass heat/electric exhaust would be truely renewable.
written by tida_hirohito, January 29, 2010
written by John for Recycling, January 30, 2010
written by anonymous, February 02, 2010
written by Nicola Terry, February 04, 2010
written by Bob in CA, February 05, 2010
The comments above regarding government research thinking "commericalization will ruin it for them" are utterly ridiculous. If it's so easy to commericalize this technology, there would be a steady stream of venture capital to do it. I've worked in a federal research lab and the attitude is exactly the opposite. If federal research efforts prove the potential for commercialization it helps to validate those efforts, not undermine them, and such a success looks very good on one's CV. Federal research money should be spent on the basic research no one else will fund. Once the potential is shown for a technology, private capital should commercialize it.
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