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August 02, 2012

Using halophytes to grow fuel

Halophytes are salt-tolerant plants that are found throughout the world. Halophytes can be used to grow both fuel and food, and a NASA facility is attempting to use halophytes for large-scale fuel production. The aim is to create aviation-grade biofuels without using any arable land, freshwater, or standard food crops. Dr. Bilial Bomani, the head of NASA's greenlab research facility, has dedicated his career to using halophytes to create food and fuel. In an interview with Sander Olson for Next Big Future, Dr. Bomani discusses how halophytes could be used to create vast amounts of biofuels, and food in an environmentally benign and sustainable manner.

Bilal Bomani

Question: You oversee a NASA project to create "extreme green" biofuels. How did this project arise?

In 2008, with the help of Robert C. Hendricks, we came up with the “eXtreme Green” plan to research the next generation of biofuels. Our “eXtreme Green” plan came with three main limitations. First, we could not use fresh water, which is in increasingly scarce supply. Second, we could not compete with food crops, so no food crop fuel production, such as soy beans or corn. Finally we could not use arable land. So the solution we came up with relies primarily on algae and salt-tolerant halophytes. Our Halophyte biofuels program was instigated by Dennis Bushnell – Chief Scientist at NASA Langley Research Center.




Question: How many halophyte species are you growing? Can these halophytes grow in any salinity, from freshwater to saltwater?

We are growing four species of halophyte plants, all of which can grow in any salinity. They can go from freshwater to saltwater and back. There are thousands of species of halophytes, and we investigated and experimented with 30 different halophyte plants and settled on four optimal species (Salicornia virginica, Salicornia bigelovii, Salicornia europea and Salicornia subterminalis). Most plants on the beach are halophytes. Since this lab is "extreme green", everything we do has to be renewable, sustainable, and alternative. In addition we are investigating a variety of algal species, both macro and micro under similar conditions.

Question: Is it possible to run current planes only on biofuels?

No, the seals and fueling systems of legacy aircraft aren't designed for biofuels and will leak if loaded with pure biofuels. So we have created a "bio-blend" consisting of 95% aviation fuel mixed with 5% biofuels. However current specifications ASTM D 7566 allow to 50% blends and some demonstration flights have shown it can be done even to near 100% alternate fueling.

Question: Can you create a biofuel that won't cause leaking?

Yes, but the fuel would not satisfy extreme-green requirements. The planes’ fueling systems would have to be redesigned in order to accept pure biofuels. Since that is an expensive and time-consuming proposition, we are currently concentrating our efforts on creating bioblends. But at some point in the future we will need to design a plane that can run on pure biofuel; the problem will be how to fuel the legacy aircraft in the fleet and that could be solved by limiting to less than 50% biofueling.

Question: Can halophytes be engineered to produce gasoline?

Yes, but that would be under the jurisdiction of the Department of Energy, so we don't engage in that research.

Question: Are your halophytes genetically engineered?

Theoretically, halophytes can be genetically engineered to create all manner of products, and other groups are looking into that. At this time, producing biofuels using genetically engineered halophytes would be prohibitively expensive. Our group does not engage in any genetic engineering research; we are focused on natural selection methods.

Question: So instead of using genetic engineering you optimize the growth parameters using fertilizer?

We don't use any synthetic fertilizer. We use only fish waste, which is readily available, as a completely "green" fertilizer. We are planning a halophyte farm on private land along the Mississippi river, which has abundant fish waste.

Question: Can halophytes be used in land remediation?

Yes, and we have recently done just that. In 2007, hurricanes salinitized soybean fields, rendering them barren. So we introduced a native species of Salicornia halophyte into the fields, which should produce useable crops and desalinize the soil in the process. In companion work with Prof. Gallagher at University of Delaware, a soybean field fallowed by hurricane floodwaters was planted with sea-shore mallow that produced usable seed even in a dry season. Our halophyte and remediation technology could also be applied to pumped aquifer irrigated farm lands which are becoming more salinitized every year.

Question: Is the energy density of biofuels comparable to that of aviation fuels?

Yes, our biofuels meet the minimum specification set by the aerospace industry for energy density. However in terms of an aircraft tank, it has less energy per tank reducing travel range about 4%. We are still working on getting more energetic biofuels such as from castor beans.

Question: Are halophytes inherently low maintenance?

Yes, in most tropical and moderate climates, they are perennials and very hardy plants. We can keep them growing nearly continuously for several years. And they grow well in a variety of depleted soils. In the right conditions, they can even grow in sand.

Question: How much land would need to be dedicated to halophytes to supply the aerospace industry?

If we dedicated the land mass of Maryland to growing advanced algal technologies along with halophyte optimization, we could almost supply the entire aerospace industry in the U.S. If we had the land mass of the Sahara desert, we could meet the aviation fuel needs for the entire world using primarily advanced halophyte plants. We are trying to use underutilized NASA land in Florida to grow halophytes. We actually use beach sand as our soil, which normally has no nutrients. The beach sand gets its nutrients from the water below. With the projection that the aerospace industry will grow about 4% per year, current fueling requirements based on current aircraft designs is expected to double by 2025. The utilization of halophytes is a viable option for the future.

Question: What is the cost per gallon for your biofuels?

Currently it costs about $18 per gallon for alternate fuels. Although our biofuels aren't currently commercially viable just yet, we aim to eventually make the cost comparable to that for conventional aviation fuels. In order to make that happen, we would need international agreements to free up millions of acres of non-arable land.

Question: Can halophytes also be used as food? As feedstock for animals?

Yes, most all of our halophytes are edible. For example, Salicornia is currently marketed in the U.S. as gourmet food product. It tastes like asparagus or green beans, and it already has the salt in it and if gown near oceans, or stimulants, nourishing sea-salt. We have six different salt levels, so we can accommodate a variety of tastes. The halophytes do have natural predators, such as beetles, but we counter that with spiders. Goats currently eat the halophytes, since they can tolerate higher salt contents. The halophytes with lower salt density could be used as cattle feed.

Question: Do any large-scale halophyte farms already exist?

There is a "halophyte city" in Mexico where halophyte farms are in abundance. There have also been large-scale farms in Eritrea (Africa) with current trials in the Middle-East; all have been under the direction of Dr. Carl Hodges, the founder of The Seawater Foundation. These farms are producing both sustainable food and fuel. These farms aren't causing any problems; on the contrary they are alleviating problems, and if the proper agreements can be made, a massive increase in the number of these farms should be feasible.

Question: To what extent can halophytes be improved/scaled up during the next decade?

Although technology and funding always matters, the real scaleup will result from international cooperation. There is a huge amount of low-quality, unused land that could effectively be used for halophyte production. So this won't compete with arable/high value land at all. One could even grow a halophyte garden on a rooftop, if one lived by the sea.





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