Actually, you don’t burn the manure. You get energy from composting manure, which produces gas, which can be burned in turbines to produce electricity. There are some local coops that do this.
I promise this isn’t just a well askually but anaerobic digestion (what is being discussed in the article) and composting are different.
Composting requires oxygen. It produces carbon dioxide. It produces heat. Compost has less restrictions for use as a fertilizer than digested mature. I’m not from the US so I don’t want to assume it’s the same across all states but in Canada you can sell it to the public.
Anaerobic Digesters do not require oxygen. It produces carbon dioxide and methane. It requires heat input to occur at a reasonable rate. Use as a fertilizer is restricted because more pathogens survive. Hydrogen sulphide is produced so sometimes ferric chloride is added, and that reduces the amount of phosphorus available to plants.
One of the trade offs with digestion is that processing the digestate into something usable takes additional energy. If it’s a single farm and they are not taking additional feedstock it’s no more nutrients that they had before they started digesting. Chances are they can manage the nutrients on site and don’t need to input energy.
If they are taking stuff from off-site, or if they expended their operation beyond what they can manage on site then they need to choose if they are going to transport it off-site as a liquid, thicken it into cake (mmmmm), or create a fertilizer product like pellets. Each option requires more energy than the last. They may be able to sell the pellets but typically have to give liquid or cake away for free or pay people to take it.
While I really don’t think gas from manure is the grand solution to climate change like this article seems to state. It doesn’t actually make a difference when it comes to fertilizer. You don’t burn the manure itself, you burn the gas produced from the manure. Afterwards you have this black sludge that is actually an even better fertilizer than before because the digestion in the methane production process breaks down the organic matter in the manure and makes especially the nitrogen contained within shift from being tied up in proteins and organic matter to being pure ammonia and nitrate. I have myself witnessed how a local pig farmer increases his wheat yields significantly once he installed a biogas digester and started fertilizing with the pig manure digestate instead of raw pig manure.
If we are going to have animals, we might as well put all the manure into a biogas digester before using it as fertilizer. You can even run tractors off the stuff if they are properly concerted. A few farmers that have biogas digesters have totally stopped buying diesel.
However for the US specifically I think step 1 is starting to actually use the manure at all. You guys have these poop lagoons over there where the manure just rots in a pool and never gets used on the field. In the EU that’s illegal.
This industry is happy to let manure runoff into local ecosystems and lead to massive waterway pollution and toxic algae blooms. Biogas is no better with the tanks used for holding manure for biogas regularly leaking out and/or overflow
This is not an industry that is super concerned about fertilizer shortages and usage. Animal agriculture makes fertilizer demand increase and worsens the problem, even if manure was used 100% optimally
Thus, shifting from animal to plant sources of protein can substantially reduce fertilizer requirements, even with maximal use of animal manure
For an example of how large the fertilizer difference can be: Producing 1kg protein from beans uses 12x less fertilizer than doing the same from beef
To produce 1 kg of protein from kidney beans required approximately eighteen times less land, ten times less water, nine times less fuel, twelve times less fertilizer and ten times less pesticide in comparison to producing 1 kg of protein from beef
Isn’t the world in need of good fertilizer? Why would you burn this manure instead of using it in crop lands and gardens and yards???
Actually, you don’t burn the manure. You get energy from composting manure, which produces gas, which can be burned in turbines to produce electricity. There are some local coops that do this.
The leftovers is fertilizer.
I promise this isn’t just a well askually but anaerobic digestion (what is being discussed in the article) and composting are different.
Composting requires oxygen. It produces carbon dioxide. It produces heat. Compost has less restrictions for use as a fertilizer than digested mature. I’m not from the US so I don’t want to assume it’s the same across all states but in Canada you can sell it to the public.
Anaerobic Digesters do not require oxygen. It produces carbon dioxide and methane. It requires heat input to occur at a reasonable rate. Use as a fertilizer is restricted because more pathogens survive. Hydrogen sulphide is produced so sometimes ferric chloride is added, and that reduces the amount of phosphorus available to plants.
One of the trade offs with digestion is that processing the digestate into something usable takes additional energy. If it’s a single farm and they are not taking additional feedstock it’s no more nutrients that they had before they started digesting. Chances are they can manage the nutrients on site and don’t need to input energy.
If they are taking stuff from off-site, or if they expended their operation beyond what they can manage on site then they need to choose if they are going to transport it off-site as a liquid, thicken it into cake (mmmmm), or create a fertilizer product like pellets. Each option requires more energy than the last. They may be able to sell the pellets but typically have to give liquid or cake away for free or pay people to take it.
While I really don’t think gas from manure is the grand solution to climate change like this article seems to state. It doesn’t actually make a difference when it comes to fertilizer. You don’t burn the manure itself, you burn the gas produced from the manure. Afterwards you have this black sludge that is actually an even better fertilizer than before because the digestion in the methane production process breaks down the organic matter in the manure and makes especially the nitrogen contained within shift from being tied up in proteins and organic matter to being pure ammonia and nitrate. I have myself witnessed how a local pig farmer increases his wheat yields significantly once he installed a biogas digester and started fertilizing with the pig manure digestate instead of raw pig manure.
If we are going to have animals, we might as well put all the manure into a biogas digester before using it as fertilizer. You can even run tractors off the stuff if they are properly concerted. A few farmers that have biogas digesters have totally stopped buying diesel.
However for the US specifically I think step 1 is starting to actually use the manure at all. You guys have these poop lagoons over there where the manure just rots in a pool and never gets used on the field. In the EU that’s illegal.
This industry is happy to let manure runoff into local ecosystems and lead to massive waterway pollution and toxic algae blooms. Biogas is no better with the tanks used for holding manure for biogas regularly leaking out and/or overflow
This is not an industry that is super concerned about fertilizer shortages and usage. Animal agriculture makes fertilizer demand increase and worsens the problem, even if manure was used 100% optimally
https://www.sciencedirect.com/science/article/abs/pii/S0921344922006528
For an example of how large the fertilizer difference can be: Producing 1kg protein from beans uses 12x less fertilizer than doing the same from beef
https://pubmed.ncbi.nlm.nih.gov/25374332/