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Tony and Axel Barren Energy discusses cactus to gas

Tony and Axel of Barren Energy discuss How to Make Biofuel from Cactus and Its Many Uses

Cactus to gas is a bioenergy solution that converts cactus into a renewable biogas. This process involves using these hardy, drought-resistant plants to generate energy-rich biogas through anaerobic digestion or fermentation. This innovative approach holds potential in addressing energy challenges, providing sustainable fuel alternatives, and mitigating environmental impact.

Tony and Axel Barren Energy discusses cactus to gas


We aim to become the sustainable feedstock of more marginal lands and produce provide the bio industry of the future with this sustainable feedstock. It's not only gas we can. We can produce vegan leather from the cactus. We can produce different types of fiber and extract for paper for production. We can also use the cactus for other type of fermentation products.

So, you know, different types of amino acids and organic acids that enter into the composition of other kind of industrial products that are bio sourced. Also the feed, the fermentation for protein production and soybean replacement. So it has a lot of potential benefits. And let's say it's all sugar factory for fermentation of bio industries in marginal land.


Hello and welcome to Rethink What Matters, the podcast dedicated to aligning the economy with the ecology and everyone for improved business performance, stronger families and a greener, cooler planet. And today I'm joined by Tony Dean and Axel Taris of Barren Energy, Western Cape, South Africa. And we're going to be discussing a cactus to gas.

If you could tell us about that energy, then please. Tony That'd be great.


Yeah, great. Thanks for having us on the podcast today. Paul As you know, I'm Australian and I'm away to South Africa and the company was at that stage working with big miners, Anglo and Rio Tinto, and they were looking for ways to reduce their carbon footprint, etc.

Barren Energy went to Mexico in 2018 looking for a solution for biomass to make bio gas from a range of various feedstocks. And in the process we found cactus and cactus, through all the testing proved to be our number one choice. And so we said, I think that's the right solution. Where can we do that In South Africa? Barren energy found a property in the Free State, which is in the middle of the country, and it's very close to the University of the Free State that actually know the most that cactus in South Africa. We found a farm that had been used as a research station for 20 plus years, the farmer, same age as me sixty. So he was born on the farm and cactus is part of his life. And we were fortunate to be able to purchase the property and take over his initial plantation of 40 hectares on a total area, a little over 1000 hectares. And we've since in increased the farm size to 200 hectares on the plantation and still growing.


Okay, so. So why South Africa? Why cactus?


Well, I guess one of the reasons we are actually in South Africa with cactus is Australia has spent the last 95 years trying to eradicate what we often refer to as prickly pear. And prickly pear is often confused with spineless Opuntia here and we are growing, spineless Opuntia.So it's not an invasive weed species which Australia have to get rid of.

And so if we mention the generic term cactus in Australia, it's a no go zone. And so South Africa had a modest amount of cactus already under plantation for fodder supplement to the cattle industry and there was some fruit demand, they call it Turks FE in Afrikaans if I pronounce that correctly, and they really enjoy eating the fruit of the plant.

So we decided that South Africa then, since we already had an energy management business here in South Africa, we would tack this into that business and go for the biomass to make Biogas. And that was the journey. And so I moved to South Africa in 2020, right on Covid. And we really haven't looked back since. It's been a terrific journey and our issue is getting the farm into what we call a source farm so we can cut the cladodes, paddles whatever people want to call it so we can plant them and propagate them.

And that's what we're chasing now, is the quantity of those to do that process.


Did you have to, so did you have to actually do a lot of work on the farm to get it up and running.


Yeah. So when we bought the farm, as I said earlier, it was 40 hectares was effectively a fruit orchard and it's planted 1000 plants per hectare. But for us to maximise the, the land availability, we need to increase the density to 20,000 plants per hectare. And so last year we planted 1 million cladodes which we cut from the farm. This year, right, Plant a million again and then the following year in 2024 from our previous plantings, we will be able to complete the 500 hectare planting using 10 million cladodes we cut off our own farm and that's the difficulty in South Africa and anywhere else to do cactus planting.

Where do you get the raw material from? So we've developed our own farm to get the raw material.


If you could just tell us a little bit more than about the process of converting cactus to gas. Can you do this with any type of cactus So are you growing your own cactus?


Okay. So Paul then basically the cactus that we are using from the Opuntia family and we are using spineless varieties of these cactuses that are planted in high, high density and our purpose is not to produce the fruit and then use the fruit, it's to plant these crops in high density, have the highest amount of pads you know, the cactuses that have those kind look hand shaped pads.

And those cactuses, when there are managed as a normal crop, but in environments that doesn't enable other crops to survive, we are able to produce those that are a meter and a half high cactuses in less than 18 months in the first year. And then it's a perennial crop that will yield continuously every year for the next 2015 to 20 years.

So the cactus is harvested with the machinery. Those machinery exist now and that cactus is brought to a shredder that chop and turn that cactus into a juice, just as what you would have in a carrot juicer. And those juices get into a big tank. The big tank is maintained at 37 to 40 degrees temperature, similar to the body temperature of a cow.

And then it's inoculated with some animal manure, a small amount of manure. And those bacteria that we have also in our intestines digest the sugars that we have in the cactus and then release biogas. That biogas has 30 to 40 percent CO2. And the remaining is methane biomethane. So that gas can be then directed as are to produce electricity or to be separated from the CO2 into gas and be used for further industrial purposes.

Just like Tony mentioned. So it's a fantastic feedstock. It's one of the cheapest way of capturing carbon from the atmosphere as well. We could we could get into that subject a bit later if you want.


Yeah, absolutely. Love to do that. Yeah, absolutely. So

could you tell us a little bit more about the setup process of a plantation and what inputs are required to get to get one of these plantations going?


So the set up is we have a land, an initial land preparation. We establish without getting too much into details, the pads are cut, the pads are established in a row, like a furrow where the pads are established, touching one another, and then you have, let's say, a continuous line of pads that start developing the root system right then obviously the land, depending on the soil conditions, is adjusted.

You know, if it's too acidic, then you have to bring some limestone on it and um, and then provide some of the initial nutrients. And then we have to bring manure that is being sprayed onto the plantation because the plant respond very well to organic fertilization, because it absorb it has a better water retention capacity and releasing all the nutrients that is needed for the roots.

So the cactus then develop its root system that it has a very shallow root system. 90% of the roots are in the top 15 centimeters, right? The roots can go up to six meters. The strategy of this plant is that 15%, only of 7 to 10% of its biomass that it produced annually, is in its root system.

Most of plants have 30, 40% of its biomass that is that is underground. And the plant reacts like, okay, once there is like erratic, let's say you have five millimeters rainfall, the cactus is able to use it and store it in its biomass. And because it's a it has a cam photosynthetic pathway compared to C3 and C4 photosynthetic pathway.

Our listeners could Google that and learn more about it. I don't I won't go into the details of it, but yeah the um cam photosynthetic pathway enables the plant to do its photosynthesis during the day, but it do it's gas exchange of CO2 water exchange during the night while normal plants do it do it during the day and because in let's say semi-arid landscape and plateau landscape the temperatures are lower during the night, you lose much less water from evapotranspiration than you would during the day.


What are the carbon sequestration properties of cactus that I think you suggested then they're, they're very good, they're very high.


Yeah. So basically just to give you an insight on the potential, if we are targeting places that are let's say between 300 to 600 millimeter of annual rainfall, which is considered a semi-arid landscape, there's millions of square kilometers of that type of land that is currently used for extensive grazing, usually because the rainfall is too variable to be able to sustain annual crops.

And usually the carbon sequester of these kind of habitats of rangelands.

And are around three or four tonnes of carbon of per hectare per year, while our cactus, if we bring the nutrients that they need, the macro and micro nutrients that they need to develop and we manage them properly, we are able to capture around 30, 40 to 50 tonnes of CO2 equivalent per hectare per year, which is kind of a five.

Let's take up to ten fold carbon capture capacity, which is a main difference between planting trees or developing bioenergy in temperate or tropical and subtropical climates where let's say you have a forest growing and so on all let's say crop and unable to turn low potential and low carbon capture potential areas into high carbon capture areas. So we turn the semi-arid landscape into a capturing, let's say, low amount of CO2, right through being able to capture the same amount of CO2 as a temperate forest.

Right. And not only that, so the cactus capture that CO2 and as it's basically in is being digested in a gentle way. There is no burning. All the nutrients stay in that big tank and returns back to the soil. Yet we extract only carbon, hydrogen and oxygen from from that biomass and the CO2 that we capture. It's one of the cheapest way of capturing CO2 for either reuse, you know, for making bioplastics into synthetic fuels or using it for any other industrial applications and having the biomethane on top of that.

It's a it's a it's a it's a nice way of not only capturing carbon but also producing a transformed solar energy in in in a storable way in the form of biomethane.


Okay. Alright. And how does it compare to other types of biofuels or bio gases in terms of, you know, in terms of how efficiently you can convert to the energy that's needed to complete, you know, to to actually do the conversion?


Okay. So basically the highest yielding energy crop that we know today is palm oil produce 5 to 6000 litres of diesel equivalent energy. We're able to produce 6000 liters of diesel equivalent energy in areas receiving between four and 500 millimeters of rainfall. So but palm oil that you need to grow palm oil in area that was rainforest before receiving a 1500 millimeters of rainfall.

So we're able to produce the same amount of energy as palm oil in areas receiving around three times less rainfall and that are semi-arid.


How long does the process take then from extracting the the cactus out of the ground, if you like, you know, to actually producing the gas?


Um, this is a process that we, once we chop the cactus and put it in the digester we obtain, we digest the biomass in a time that is less than six days. So we extract most of the gas, but the retention time is a little bit longer. What is also interesting that we could also point is that cactus planted in high density capture between 8 to 15% of the annual rainfall in its biomass cactus is 90 to 95% water.

So let's say if you have 400 millimeters of rainfall, we might end up having 40 millimeters of that rainfall that is stored in the biomass, that creates a vegetable cover in these semi-arid landscapes and act like a natural dam that we create in semi-arid landscapes. And that has a very interesting effect on the biodiversity that we can sustain because we produce much more biomass, we have much more biomass for some reptiles, some mammals like ground squirrels.

Um, turtles are tortoise and game birds and all what sustain that food chain above that. And also the underground biomass, you know, like earth worms and or termites that might benefit from the higher availability of biomass and water in that kind of challenging landscapes.


So this is an advantage, a benefit you're providing whilst those cats are growing during the 18 months that they're growing?


Exactly. Exactly. So like a small percentage of that biomass could be eaten by light. The wildlife or the benefit and all the digestate all that water that is in the cactus that has been digested, turned back as a slurry back to the soil. So what we bring, basically we bring all the nutrients that is needed often in an organic form to the cactus in the first two years and once the cactus has started flourishing, we hope we make the first harvest 18 months after the the plantation and then every 12 months and obviously, let's say if you have a plantation that is 365 hectares, that would mean that we harvest one hectare every day and all that nutrients go back to the soil. So we have nearly. So it's not exactly, but it's nearly closed nutrient loop. So all our phosphorus, potassium and calcium goes back into the soil and most of the nitrogen is also all nitrogen volitisation is extremely low because it's a no low nitrogen containing plant. So sorry, it's a little bit technical, but it, it, it, it's it brings a little bit more kind of inside in a different perspective than usual, you know, only energy focused.


Yeah, please be technical. It's great. So now we put the detail, we want the data. It's really interesting to hear that.

so what type so you looking for semi-arid land, all the particular destinations that you're looking for at the moment.

Are there particular types of landowners that you're working with where you can put these plantations


Okay. So the, the plantations are usually the ideal areas to plant them. It's close to, let's say if you have farms, let's say, you know, dairy farms, pig farms, chicken farms, you have the nutrients already there and the nutrient then can be is often not efficiently used there, especially in semi-arid landscapes. And we can basically provide food security by providing feed as well for cattle.

So a cow is able to have 40% of its diet composed with cactus and that reduces drastically the need for annual crops that compete with food security. So we are able to provide 40% of that food. There is now new research where we can use the dried form of the cactus for poultry and even ferment it to have higher protein percentage and feed it to mono gastric animals, just like poultry or pigs.

And for pigs we can also feed it as a slurry, and that enables us to get away in areas where we use, let's say, maize and soybean and secure those livestock operations that are situated in that kind of rainfall area while improving the habitat of these areas. But we can also target very marginal land, degraded land by mining operations and revegetate areas that are degraded because it's a pioneer plant and it's often misunderstood as an invasive plant because the spine is a varieties obviously proliferate where no other type of plant can develop.

And often what happens certain studies also show that in Morocco that cactus plantation that were established 60 years ago becomes nurse plans for organ trees, you know, the Argan oil that is extremely valuable. Cosmetic oil.

The cactus, a nurse acts like a nurse plant. The small little tree gets protected by the cactus. Right. Organ tree then take over and facilitate regeneration of forest in that kind of habitat. It's also a plant that is being used, has been used for centuries in Sicily, around Mount Etna. So when the volcano used to erupt and then you had lava.

Yeah, farmers used to take those pads and establish those pads in the rocky basaltic landscape. Have that cactus grow for 20 years where it accumulates organic matter and dust and so on, and basically generate that soil layer that is needed for establishing grapes. And if you look at grape culture in Sicily, they they develop it in an on Mount Etna up to 700 meters.

The reason why you don't have grades above that level is because cactus is tolerant to frost up to 700 meters in Sicily. And and which is a very interesting fact. So it's a pioneer plant generating soil and generating soil 5 to 10 times faster than any other crop.


Wow. That is a thing. That is a huge thing because I know that soil is a is a big problem, isn't it?


So that soil erosion is a huge problem and having a plant that is able to withstand very marginal shallow soils and generating that organic matter, enabling other plants to establish is a huge advantage for increasing the resilience of our agro ecosystems. Right? Yeah.


Can you tell us a little bit more about the biodiversity site then of this site?


So yeah, so the biodiversity, so our way of maintaining kind of a resilient cropping system on our approach is to have the cactus instead of having the cactus on a monoculture and having, let's say a desert of cactus and erasing all other kind of plants because we want the cactus is we use cover crops in between the entire rows of cactus.

You fix nitrogen, we plant them in a in a in a mixed way. So we have the whole diversity of annual crops that are planted or semiannual plants planted in between the cactuses. Most of them are nitrogen fixers. Those nitrogen fixing plants fix nitrogen, provide food also for all the through soil food, web. And we use those plants as well as a mulch.

And that mulch basically enables the cactus to thrive even in a better way. And those are those plants that are planted in between instead of grass. Have most of them have flowers. And so they are extremely beneficial for pollinating insects. So we are able to sustain a certain level of pollinating insects in our cultures. And we also aim to establish hedgerows of native plants every, you know, every couple of hundred meters so that we decrease the wind speed and enable for local wildlife to thrive in our plantations.

So we we we are planning on basically planting a minimum of 8000 trees per square kilometer of cactus planted, which would enable a lot of, you know, birds and mammals to make their habitat thrive in those kind of habitats.


Sounds amazing. Yeah, that's a really amazing thanks for sharing that Axel. What are the real challenges to this view then, in establishing this business? What what have you had to overcome?


So. So I can I can say I can answer if you want, quickly. Yeah. So the main challenge is this. This cactus crop has been used. There's more than 600,000 hectares of cactus planted in northeast Brazil for forage purposes. So they use it for dairy cows as a feed for cattle and it enables that whole region to be more resilient to climate because they have extremely variable rainfall that can vary from 200 millimeters to 600 millimeters.

And these high density intensively managed cactus plantations. The technique has been developed by a guy called Paolo Swasuna in northeast Brazil and Paolo Swasuna developed it around 20 years ago and the first machinery to harvest cactus has been developed and put on to market this year. In 2023 in northeast Brazil. So the main problem that was, let's say hindering the development of high density cactus plantation is okay, we plant this by hand already.

How do we harvest it? And the harvest, okay, it's a manageable thing if you have small holders with one, two, 3 to 5 hectares of cactus, chop it, bring it to the cows and feed it to the cattle. But nobody wanted to develop and adopt that kind of it's, let's say the industrialization. When I say industrialization is all the mechanization that comes with it has been developed relatively recently, in fact very recently compared to other crops like maize, lucerne, and that kind of crops.

But know that with all the climate change and, you know, adaptation, this plant with the new mechanization and so on and the adoption in a larger scale and the bottleneck was the mechanical of harvest. And now we have a machinery that can harvest up to 150 tons of cactus per hour. So we are able, let's say, with a machine that would run 10 hours, be able to harvest 1500 tons of green cactus every single day.


Is this biofuel displacing other biofuels? Because it's either cheap, cheaper, it has, you know, better properties and in some other way?


No, it doesn't. Our aim is not to. It's not to replace another biofuel or something like this. We don't. We just want to be able to provide sustainable fuel, sustainable feed, sustainable food in areas that are where there is no other opportunities or and create that job employment opportunities where they really like.


That's interesting. It is a bit broader, isn't it? I mean, you have been talking about that, so we're not really just talking about cactus to gas then know we are talking about cactus to feeds and foods and biofuels and


Yeah, exactly. So imagine we are pushing now in the world into biodegradable, sustainable feedstocks. And most of the you might have noticed, you know, the cork of the new dividing edible corks that they developed for wineries or packaging solutions. All of these are driving the need for, um, biodegradable feedstock like, okay, yes, we can use forest, but up to a certain point we and the other feedstock that we use are either corn that we turn into starch, the starch, it's turned into sugars and the sugars are then fed to bacteria to produce bioplastics or acid that turn into bioplastics or that kind of things.

And sugar cane and sugar beet. But if you think about maize, sugar cane and sugar beet, all of these crops need regular rainfall when they are growing and they can be only planted in certain areas.

While cactus has 30%, easily digestible sugars. Yeah, it has very low lignin, very low, quite low cellulose. It has only 15% cellulose. It has its let's say we aim to become the sustainable feedstock of more marginal lands and produce provide the bio industry of the future with this sustainable feedstock. It's not only gas we could we can produce.

You know, people might have heard people producing fake vegan leather from the cactus. We can produce different types of fiber and extract for paper pulp production. We can also use the cactus for other type of fermentation products. So, you know, different types of amino acids and organic acids that enter into the composition of other kind of industrial products that are bio sourced.

And also the feed, the fermentation for protein production and soybean replacement. So it has a lot of potential benefits. And let's say it's our sugar factory for fermentation of bio industries in marginal land.


Okay, So you're working in very hot areas and I'm assuming that there's quite a lot of energy involved in this process. But does it because you're working in these hot areas I mean, you can generate your own energy. You don't need to take anything from a local grid.


Well, we one of the beautiful thing that we can develop that we're working on is also one option is you have let's say we grow this cactus where there is a lot of sunlight, okay? Solar PV is one of the cheapest way of producing electricity today.

But what happens what the beauty of the cactus is that we are able to turn around the 1 to 2 to 1 to 2% of the solar radiation into methane. So okay, people might say, oh, but solar panels are 14% efficient. Yes, there are certain 14% efficient, but they are not in a storable it's not a storable energy.

So what you can do is have solar panels providing electricity during the day and when you or you have clouds or that you have no electricity, you can supply that stored form of solar energy, which is the biomethane produced from cactus and have a stable electricity solutions run or for lower tank and lower tech decarbonized transport, transportation We have CNG, you know, compressed natural gas well, this would be compressed biomethane and we are able to run our tractors that we use on biomethane, we are able to use that gas as well for the integral weeding.

We're able to use that energy let's say have or be autonomous in that sense.


So if you could just tell us a little bit more about how is the biogas being used now after it's being sold, for example, after it comes out of your digester?


Yes, Paul. So we have different potential fuel options for the use of biogas. So the simplest way is to use the biogas and to replace natural gas paraffin as a fuel to burn in boilers. That's the first option. No separation of CO2 and methane. The biogas is directed role into burners. And we let's say pasteurized milk or we use it for any other kind of heat purposes.

Second option is to direct that biogas that is being filtered from sulfur and other kind of content, let's say small particles, and then it's directed to a gas generator. And that gas generator is being run with the biogas, and we produce heat and power. So electricity to provide the electricity locally, the heat, and then can be in the form of, you know, steam or hot water.

Um, the sort of first force options are we take the biogas, we direct it into a separation unit where we separate the CO2 and we separate the biomethane. So now the biomethane is a complete molecularly. It's, it's, it's equal to natural gas. So it can be either compressed into CNG, compressed natural gas or compressed biomethane, or it can be injected into the gas grid, which is being done in certain European countries for it can be cooled down and turn into liquefied biomethane to transport it into further distances.

And a force option is also ANGI, which is absorbing natural gas, which are bottles filled with active carbon and of the biomethane then can be stored in lower pressure than CNG bottles. Those CNG bottles. So obviously we can use it to replace LPG and other fuel uses and all the different uses that we can do with natural gas.

But the beauty of it is that we can run busses, tractors, cars with biomethane. So for example, Italy has 1.4 million CNG powered cars and we can see a lot of them in European cities, you know, CNG or biomethane powered busses, right, to reduce the carbon footprint. And then we have a let's say a fifth or sixth step which is directing that biogas into Fisher crop units.

Fischer-Tropsch is a technology that was developed in the past early century in Germany and the Fischer-Tropsch unit is basically pressure turning that biogas potentially to synthetic gas. And we use a catalyst to produce synthetic fuels. But because the CO2 is from renewables source and because the biomethane is from a renewable source, we would be able to produce sustainable aviation fuel.

So bio kerosene or synthetic biodiesel or synthetic petroleum. So that's the and today we have Fischer-Tropsch units that can work with 70% efficiency. And it can really be very interesting because we would be able to produce more than 6000 liters of synthetic of Aviation fuel per hectare in semi-arid landscapes. Just to give you an idea.


I really appreciate your time on this podcast, we learned so much about your business and turning, you know, cactus into gas and into into feedstock. It's been really interesting. We've learned a lot. Thank you. Thank you very much for your time.


Thank you very much, Paul.

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