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Features Biodiesel Bioenergy
Turning a troublesome weed into a biodiesel crop

November 30, 1999  By Carolyn King

Pennycress seeds produce superior quality biodiesel. Despite its unflattering name

Despite its unflattering name, stinkweed has some excellent qualities as an oilseed crop for biodiesel production. The plant grows abundantly across Canada. It seems to require few inputs to grow even under tough conditions. It has oil-rich seeds and the biodiesel from its oil has superior characteristics. As well, it is a non-edible plant, so it offers a way to address the food-versus-fuel debate that circles around biodiesel produced from food crops. And the plant can grow on marginally productive agricultural land, which leaves more fertile land for growing food crops and offers farmers in these marginal areas a lower-risk crop option.

So, even though converting a weed into a commercial crop requires a significant effort, those involved with stinkweed’s development are optimistic about its potential.

Stinkweed (Thlapsi arvense) is known by several other names; in its emerging role as a crop, it is referred to as pennycress, and like canola, it belongs to the mustard family. Typically it grows as a winter annual, germinating in the fall, overwintering and then starting to grow again in the spring. As a weed, it is managed in crops through the use of herbicides, and at least one country has quarantine regulations regarding grain contaminated with stinkweed. The plant contains toxins and cannot be used for human food or livestock feed.


Stan Peacock, a farmer in the High Prairie, Alberta area, is a driving force in the development of pennycress as a crop. He explains, “As a farmer on marginal land and typically a rancher, with the price of cattle up and down so much, you’re always looking for something that you can make a better living at.”

He saw the potential for a biodiesel facility in his region and was approved for funding through the federal government’s ecoAgriculture Biofuels Capital Initiative. To make the proposed facility economically feasible, he included a seed-crushing facility as part of his business plan and began looking for low-cost oilseeds as biodiesel sources.

He happened upon pennycress’s potential by accident when he was crushing canola seed. “We had stinkweed mixed in the canola seed and we left it there to see what would happen. And the oil actually came out easier and better than straight canola. So then I grew some pennycress, and we crushed that and it worked out great.”

Since then, Peacock has been growing pennycress on his own farm and working with researchers at several agencies, including Alberta Agriculture, Food and Rural Development (AARD) and Olds College, and with other farmers to develop pennycress’s potential.

Determining pennycress agronomics
Dr. Kwesi Ampong-Nyarko, a special crop research scientist at AARD, is investigating pennycress agronomics in a three-year project, which started in 2009. Until now, most pennycress research has focused on controlling it as a weed, so Ampong-Nyarko and his research team need to determine the basics of producing pennycress as a crop. They are using small-scale controlled research in Edmonton to investigate a wide range of factors including seeding rates and densities, fall seeding versus spring seeding, crop physiology, fertilizer needs, weed control needs, yields in marginal areas and economics.

One of their biggest achievements so far is the development of a treatment to overcome seed dormancy. Ampong-Nyarko explains, “Pennycress seeds have dormancy, which means that under favourable conditions, only a small portion of the seeds will germinate. The seed also appears to require light before it will germinate, so we could not plant them using a normal seed drill. We are looking to understand the seed germination mechanisms and the post-harvest seed storage conditions that would remove the dormancy from the seeds.”

With the seed treatment they have developed, they have shown that pennycress seed can be planted using a normal seed drill and will germinate within seven days.

Another important finding is that pennycress has a very short time to maturity. “For instance, in 2010 we planted on April 15 and combined on August 9,” says Ampong-Nyarko. He notes the mature seedpods tend to shatter, so the crop should be harvested early to avoid that problem.

The seed yields from the small plots have been good, averaging about 53 bushels per acre, but the yields have varied greatly from plant to plant. “Pennycress plants are very plastic,” explains Ampong-Nyarko. “By that I mean they can be large or small, depending on the environment they grow in. For instance, you can have a plant with no branches, just a single stem, and one with 15 branches. We have found seven to 15 seeds per pod, and the number of pods per plant varied from 146 to 2055. The yield per plant ranged from 1.5 grams to about 35 grams.”

This plasticity suggests the potential to improve pennycress yields through advances in agronomics and breeding.

Ampong-Nyarko also has started looking into how agronomic practices affect the seed’s oil content. “In my research trials in Edmonton, the highest oil content was for those germinated in the fall (29.3 percent), followed by those germinated in early spring (28.6 percent). The summer crop had the lowest oil content (25.75 percent). My research also showed oil content differences between winter annuals from High Prairie (29.2 percent) and Rycroft (26.90 percent).”

Peacock carried out field trials in 2009 at plots in the Grande Prairie, Rycroft and High Prairie areas. In 2010 he focused on enhancing pennycress production on his own farm. In 2011, he plans to grow 1000 acres of pennycress. 

He says, “The first big challenge was getting seed that would germinate when we wanted it to. It’s been about a three-year breeding program on our farm and we can grow a fairly consistent crop now.”

Peacock is finding the crop needs few inputs. “Pennycress has its own bioherbicide and pesticide values. If you grow a pennycress crop, it pretty well eliminates the other weeds.”

In the very dry conditions in the Peace region in 2010, his pennycress crop did relatively well compared to his other crops.
Peacock seeds pennycress in the fall and harvests it in the summer. He says, “You’re combining it in June, July or August, so you’ve got a cash return where typically you never had one before. So your cash flow is better and you spread out your workload.”

As well, Peacock is working with farmers in Ontario, Michigan and New Mexico who are growing pennycress, and he has had calls from farmers in Texas and Alaska who are interested. “These people are in the same boat as we are. They are looking for something that costs less to grow and hopefully they can make a better living on it with less risk.”

For pennycress, as for any other crop, growers need to prevent volunteers from becoming weeds in the next crop in their rotation. Pennycress is regulated in a grain commodity by at least one country. Dr. Kanwal Kochhar of the Canadian Food Inspection Agency (CFIA), reports that Mexico requires that canaryseed consignments are free of 65 different regulated weed species, and pennycress is one of them. She notes that growing pennycress as a crop for biofuel should not have direct implications for canaryseed production, but she reminds growers of pennycress’s quarantine status so they can avoid any indirect effects on canaryseed exports.

Pennycress for biodiesel
Pennycress is one of several oilseeds that biodiesel researchers at the Olds College School of Innovation (OCSI) in Olds, Alberta, are testing. “We’ve got a small-scale pilot diesel plant and we do lots of research on alternative crops that could be used for fuel production. Rather than using food-grade oil, we look at using off-spec canola, pennycress, camelina, and even algae,” says Tanya McDonald, an OCSI research scientist.

She notes, “Biodiesel is a renewable fuel; it can be a replacement or it can be added in a blend with regular petroleum diesel. With provincial and federal mandates coming forward about using a renewable product in our fuels, there is a growing market demand for biodiesel.”

OCSI testing shows pennycress produces superior quality biodiesel, especially in terms of its cold-weather performance. “Pennycress oil produces biodiesel with an extremely low cloud point (the temperature at which the fuel starts to freeze) relative to other oils we’ve tested. That gives pennycress a huge advantage in using it for biodiesel to be burned in the winter in Canada,” says McDonald.

Processing biodiesel from pennycress seed uses the same type of equipment and procedures as producing biodiesel from canola seed. McDonald adds, “Pennycress seeds have lots of oil and are very easy to press. We’ve seen a big range in the seed’s oil content from about 29 to 35 percent because pennycress hasn’t been developed to the same extent as canola, where you have quite a defined oil content around 42 to 44 percent and then higher with some of the hybrids.”

McDonald is optimistic about the future for pennycress biodiesel. “Right now there isn’t enough pennycress being produced to meet any large-scale demand for biodiesel production, but we’re hoping that will change over time. Now that Stan has quite a significant acreage, we’re looking at producing the majority of our biodiesel from pennycress oil by next year, to demonstrate the advantages of that.”

Potential for other products
When pennycress seeds are crushed to make the oil for biodiesel production, the leftover part is pennycress meal. Both AARD and Olds College are exploring various ways to use the meal.

Unlike canola meal, pennycress meal cannot be used as livestock feed because pennycress has high levels of toxic compounds called glucosinolates. McDonald says, “If dairy cattle get into the weed, then the compounds can give the milk an odour. And the compounds cause thyroid dysfunction. So to use pennycress meal as livestock feed, you would have to look at extracting those compounds from the meal. Or you need to find other uses for the meal.”

Ampong-Nyarko is examining the meal’s use as an organic fertilizer, a bioherbicide and a biofumigant, and the preliminary results look promising. For example, in his greenhouse studies to test pennycress meal as a bioherbicide, he found the meal inhibited germination of many weeds, including scentless chamomile, downy brome, cow cockle, flixweed, green foxtail, redroot pigweed, kochia, lamb’s-quarters, stinkweed itself, and dandelion. He says, “It would require high application rates, so we think the meal would be suitable as a bioherbicide for low-acreage, high-value crops in horticulture, for instance.”

He is working with Alberta rhodiola growers to test the meal’s weed control benefits with that crop.

At Olds College, the Prairie Turfgrass Research Centre has found the meal has benefits for controlling dandelions and snow mould in turfgrass. And OCSI is looking at ways to use the meal for energy generation, such as pelletizing it for burning in the same way as wood pellets.

Peacock is collaborating with various researchers to pursue other possibilities, such as using pennycress oil for things like cosmetics and pharmaceuticals. As well, he is working with a US company, The Power Alternative, to test pennycress’s properties for phytoremediation; that is, using the growing plants to remove heavy metals and other contaminants from the environment. They have test plots as part of an initiative to convert abandoned industrial land in Detroit into green zones.

A vision for rural development
Even though development of pennycress is still in the early stages, it shows a lot of promise. McDonald says, “If you look back at the evolution of canola, it took a long time and a lot of investment. I think, like canola, it’s going to require a significant amount of investment and time to bring pennycress to commercialization, but I think it has a huge potential.”

Peacock believes in that potential. After 40 years as a rancher, he has sold his cattle to keep his pennycress work going. He has created two companies, the Green Fuel Company Inc., for pennycress research and production, and All Peace Industries Inc., for the planned crushing and biodiesel facility.

He says, “We have the facility to a point where we are ready to go. Our permitting and environmental assessment are fairly well in place, and our equipment and our contractors are sourced. It’s the funding end that is still a problem.” According to Peacock, obtaining funding has been a challenge for several reasons. He says it seems as if his approach “from the ground up, from agronomics to crushing to biorefining to retail” does not quite fit with the eligibility requirements of most funding programs. As a new crop, pennycress does not have a commodity group to advance its interests. And as a low-input crop, agri-input companies are likely not interested in investing in its development.

Peacock’s long-term vision is for pennycress production in marginal areas with small crushing and biodiesel facilities spotted across Canada. These facilities would provide a place for local farmers to sell their crops and might also create a nucleus for the growth of other businesses in these marginal areas. In fact, key funding for pennycress research in Alberta is being provided by two regional development agencies, the Lesser Slave Lake Economic Alliance and Peace Region Economic Development Alliance.

McDonald predicts, “If we can get some of the answers that Stan is looking for and demonstrate pennycress’s potential and combine that with the upcoming market demand for biofuels, pennycress could be a huge success.”


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