PNNL study finds US could grow enough algae to produce 25B gallons of fuel per year
21 May 2013
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| Trade-off analysis map showing the available and least expensive water option for each site. Sites where water supply costs are <20% of biofuel value are colored according to the least expensive available source. Where freshwater was not available and alternative water cost was greater than 20% of biofuel value, the water costs are displayed as a percent of biofuel value. Credit: ACS, Venteris et al. Click to enlarge. |
A new analysis by researchers at the US Department of Energy’s (DOE’s) Pacific Northwest National Laboratory (PNNL) finds that the US’ land and water resources could likely support the growth of enough algae to produce up to 25 billion gallons of algae-based fuel per year—one-twelfth of the country’s yearly needs. The partial techno−economic assessment was based on the availability of freshwater, saline groundwater, and seawater for use in open pond algae cultivation systems.
Achieving larger production volumes would require the utilization of less water-efficient sites and relatively expensive saline waters, they suggested. Freshwater availability and saline water delivery costs are most favorable for the coast of the Gulf of Mexico and Florida peninsula, where evaporation relative to precipitation is moderate. The results are published in the ACS journal Environmental Science & Technology.
The team in an earlier study had estimated US algal production potential assuming that all suitable sites have unlimited freshwater—i.e., alternative saline water sources were not considered. In this expanded study, they constrained freshwater supplies and estimated the delivery costs of saline alternatives for sites lacking freshwater.
| “While there are many details still to be worked out, we don’t see water issues as a deal-breaker for the development of an algae biofuels industry in many areas of the country.” —Erik Venteris, first author |
In the earlier study, water consumption was limited to evaporation; with the addition of saline resources, they we modeled the added water demand required to maintain salt concentrations in the pond (“blowdown”). For the new study, they economically constrained the use of saline groundwater and seawater with GIS-based cost−distance models of operating and capital costs.
The model uses water consumption and biofuel production rates in conjunction with the water availability model to assess the range of viable water options and the most cost-effective source for each site. Freshwater was modeled as the primary water source, as it is usually the least expensive due to proximity and minimal blowdown and concentrate disposal expenses.
For its analysis, the team limited the amount of freshwater that could be drawn in any one area, assuming that no more than 5% of a given watershed’s mean annual water flow could be used in algae production. That number is a starting point, says Venteris, who notes that it’s the same percentage that the US Environmental Protection Agency allows power plants to use for cooling.
Geographic climate contrasts result in marked differences in water use efficiency among sites, varying by 3 orders of magnitude across the US. Freshwater consumption rates (evaporation minus precipitation) are largest in the southwestern US and lowest in the eastern US. Saline water is a potential alternative, as algae can also be grown in waters ranging from brackish to hyper saline. However, the use of saline alternatives amplifies the geographic patterns in water consumption (and attendant costs) because additional water must be discharged to maintain a constant operating salinity (blowdown), which increases with net evaporative loss.
For example, the national average annual freshwater loss is 2,950 m3 ha−1 for sites with available freshwater and 10,740 m3 ha−1for sites without. Assuming a seawater source with a salinity of (35 g kg−1) and a pond operating salinity of 60 g kg−1, the average annual water use for sites without freshwater more than doubles to 25,780 m3 ha−1. An additional issue not considered in this study is the disposal costs for saline concentrates which also increase with blowdown.
—Venteris et al.
Venteris and colleagues weighed the pluses and minuses of the various water sources. They note that freshwater is cheap but in very limited supply in many areas. Saline groundwater is attractive because it’s widely available but usually at a much deeper depth, requiring more equipment and technology to pump it to the surface and make it suitable for algae production. Seawater is plentiful, but would require much more infrastructure, most notably the creation of pipelines to move the water from the coast to processing plants.
Our expanded analysis does not change the general geographic conclusions of Wigmosta et al. From a water resources perspective, the largest portion of the production potential occurs in the Texas Coast, South, Florida Peninsula, and the South Atlantic Coast, where the majority is based on inexpensive freshwater. However, as this is not a full techno−economic analysis, no judgment is made as to the economic viability of any region and there are many issues requiring further exploration before definitive conclusions can be reached.
A source of uncertainty in this and similar analyses results from lack of knowledge of commercial scale algae biofuel production rates and the potential for temporal instability in fuel prices...Several aspects of the current modeling approach also introduce uncertainty in our geographic conclusions. The assessment of freshwater resources is approximate at best. We assume a steady supply based on long-term means. However, the availability of this water source is subject to interannual weather variations as well as long-term climate trends.
...Likewise, national-scale information on saline groundwater occurrence, chemistry, and availability is limited in both completeness and quality. The results point to the need for high-quality geologic assessment of saline groundwater in the western U.S. to better understand the strengths and limitations of this resource...Finally, total costs to utilize saline resources are likely underestimated, as the model does not account for concentrate disposal, a serious issue for inland sites,28 but less likely so for those proximal to the ocean.
—Venteris et al.
The work was funded by the DOE’s Office of Energy Efficiency and Renewable Energy.
Resources
Erik R. Venteris, Richard L. Skaggs, Andre M. Coleman, and Mark S. Wigmosta (2013) A GIS Cost Model to Assess the Availability of Freshwater, Seawater, and Saline Groundwater for Algal Biofuel Production in the United States, Environmental Science and Technology doi: 10.1021/es304135b
Wouldn't it be cheaper to consume 1/12 less fuel?
Raising fuel economy from 24 mpg to 26 mpg would accomplish the same and that is not a real challenge?
Posted by: HarveyD | 21 May 2013 at 12:05 PM
I don't want the government mandating me to consume less. I should be allowed to use as much as I decide to purchase.
Posted by: ejj | 21 May 2013 at 12:46 PM
This kind of exercise is useful. the real conclusion: algae may be interesting, but it will never be more than 1-3% of the energy supply picture.
Posted by: Dollared | 21 May 2013 at 01:53 PM
I (we) should be allowed to consume as much as WE decide....regardless of the impacts on neighbors, environment, health, etc?
Well....I don't know if we should all go that way?
Posted by: HarveyD | 21 May 2013 at 02:10 PM
At least 50% of the dry weight of algae is animal feed. Therefore every litre of algae fuel has a coproduction of around 1kg of food. Since algae production consumes less water than almost any alternative food, water consumed for algae fuel will replace even more water in conventional food production.
--> the 5% restriction makes no sence. The more water used for algae, the less water is used in total. (If the coproduced biomass is used intelligently.
Posted by: Alain | 21 May 2013 at 02:25 PM
ejj,
Sure, when you find a way to live without affecting another human being, then knock yourself out. Until then, you can deal with the real world like the rest of us.
Posted by: DaveD | 21 May 2013 at 03:04 PM
More theoretical answers to questions that no longer need to be asked.
Truly your government in action, spending money.
Posted by: D | 21 May 2013 at 03:36 PM
Why don't these questions need to be asked, D? How much should venture capitalists and energy companies spend on algae fuels R&D? A lot or a little? Aren't they glad now that they have a survey of the likely maximum of production so they can forecast a best case scenario?
If I were a capitalist I would love to have that information. And no algae startup would have the resources to fund it. So it seems like government is helping business here.
Posted by: Dollared | 21 May 2013 at 04:14 PM
ejj, if you paid the full cost of what you are consuming, there would be no argument. Unfortunately, fuel like electricity, water and other essential services are priced artificially low through long-standing government subsidy.
Carbon emissions, depletion, defense of overseas supplies and pollution (not to mention sufficient road taxes to maintain infrastructure) are all externalities not factored into the pump price. Algal fuel would, at the very least, be carbon neutral and less polluting otherwise. Government has a strong interest in reducing externalities. If there were any justice, people would pay the full true cost of fuel--which could be upwards of $10-15/gallon. At those prices, you would self-ration, (and stop blaming the government for "mandating (you) to consume less."
Anyway, CAFE standards are on their way to 52.5mpg, so the issue is moot. The government has decided to take the approach of regulating consumption--rather than the more honest and transparent route of true-cost pricing.
Posted by: Sean Prophet | 21 May 2013 at 04:50 PM
I have no problem with algae fuel. I hope an innovative enterprenuer or corporation will figure out a way to produce it at a fraction of the cost of petrogas. However I have a right to use as much gasoline, petro or algae or whatever, as I decide to buy.
Posted by: ejj | 21 May 2013 at 06:26 PM
ejj,
And I have a right not to have my asthma kick in because every moron on the face of God's green earth wants to see how much gas he can burn. Why are your rights more important than mine?
Posted by: DaveD | 21 May 2013 at 07:24 PM
“the 5% restriction makes no sence ”
It makes perfect sense. First off it is not a restriction it is a thumb rule for estimating environmental impact. Energy provides a huge benefit but regulations require that we show producing it has insignificant environmental impact. I have at two nuke plants that were considered dry sites. The amount of water used in cooling tower makeup was significant in terms of the absolute number but was small when compared with the water use by the million families served by the power plant.
When it comes to an actual project you have to demonstrate to get a permit that there is a benefit to society and the actual impacts are mitigated. One way of showing that is that a co-product uses more water to produce as Alain suggested.
Lots of people claim that producing energy has significant impact but it is based on made up problems and not data.
“And I have a right not to have my asthma kick in because every moron on the face of God's green earth wants to see how much gas he can burn. ”
Actually you do not have a right to use you personal problems as an excuse to tell others how live. DaveD is not very smart. If you have a problem breathing because of air quality, go inside and turn on the air conditioning which will filter out the particulates.
The maroons who talk about asthma apparently do not know that the number of diagnosed cases is going up while the air quality is improving.
If you choose to live in a valley with 20 million other people who all insist on driving long distance every day maybe you should exercise your right to move someplace else.
Posted by: Kit P | 22 May 2013 at 06:50 AM
KitP other peoples' problems are exactly the reason why we need regulation, or accurate pricing of externalities. DaveD does have exactly the same right to go outside and breathe that ejj does to burn petroleum products. Those are two freedoms and they conflict. Government or another agency are required to mediate between them. That's life Kit.
Posted by: Dollared | 22 May 2013 at 10:31 AM
Kit,
As Dollared points out, this is exactly the reason we have to have some form of government, to mediate our conflicting rights. You cite some study that fits your world view, and I can find ten others that will disagree with you. There are also studies showing that poor air quality affects many things including lung capacity for growing children and heart attacks for adults and etc, etc, etc. And a vast majority of these people don't have the economic option to simply move. They are lucky to have jobs at all in this economy.
You can bring up any study you want, but if you claim that poor air quality has no effect on people's health then there is no point in arguing with you. It is clear that breathing dirty air can't be a GOOD thing.
So why pollute needlessly? But what is an appropriate level? Again, that has to be mediated because we'll never all agree. And I'm certainly not going to spend my life indoors with an AC on because you think it's the solution. I have as much right to enjoy my life as you do.
And as I've told you before, if you can't shut your mouth and stop being insulting just because you disagree with someone's opinion, then you need to go find a blog where they encourage personal attacks and get off of this one.
Posted by: DaveD | 22 May 2013 at 11:11 AM
amen
Posted by: SJC | 22 May 2013 at 03:25 PM
@Dollared
DaveD problem is between his ears. He may just be a loon or lack basic reading skills to read scientific papers. I have taken the time to point out to DaveD the mistakes he makes in reading his studies but he persists on repeating his claims.
I have posted the link many times that show the air quality is good where I live and everyplace else in American. I am not again the regulations or the technology that resulted in the huge improvement.
@DaveD
“but if you claim that poor air quality has no effect on people's health then there is no point in arguing with you. ”
My claim is that good air quality does not have an affect on people's health.
“So why pollute needlessly? ”
So who is polluting needlessly?
“But what is an appropriate level? ”
That would be an AQI of less than 70.
“I have as much right to enjoy my life as you do.”
You might start by not blaming others on your poor health. Enjoying life is a choice,
“stop being insulting ”
That is an insult but not to worry, it will not trigger a breathing problem. Stop whining about your health problems and using it as an excuse to tell others how to live.
Posted by: Kit P | 22 May 2013 at 07:27 PM
Kit,
LOL You're the typical big mouth on the internet who talks big and says things to people you'd never say to their face.
Posted by: DaveD | 22 May 2013 at 08:13 PM
By the way, speaking of stupid:
"My claim is that good air quality does not have an affect on people's health" .... so therefore, you're asserting: "bad air doesn't have an affect on people's health"
LMAO!!!
That's the worst logic I've seen in a long time, even on the internet, and that's saying something.
Posted by: DaveD | 22 May 2013 at 08:28 PM
Kit is not known for his logic, but rather his rude comments. Let's keep it about the topics that relate to sustainable mobility.
Posted by: SJC | 22 May 2013 at 08:47 PM
I wish we wouldn't waste so much time here with pointless bickering.
Kit is an intelligent man with a PhD. Please ignore the trash and find the good. There are pearls of sober wisdom buried in his productions if you don't get him so riled up that he wastes ALL of his time.
In our current situation we need all the radical thinkers and boat rockers we can find. Complacency leaves too many of us, fat, dumb and unhappy.
Posted by: Lucas | 01 June 2013 at 11:13 AM