The other day I came across an old news article from 2008 about a Dutch energy plant that burns 485,000 tons of poultry litter each year, converting it into renewable electricity. Wow, I thought. That is an old-fashioned way of getting rid of poultry litter – they must be releasing some 14,550 tons nitrogen gas into the atmosphere. All this to produce 270,000 MWh of electricity, 890,000 MWh of steam plus an ash-based phosphor- and potassium-rich fertilizer product.
Why waste good nitrogen and release it into the air?
The answer is because it will be later converted – by Haber-Bosch technology – into a nitrogen fertilizer. Which is what it was before. This back-conversion requires some 137,000 MWh of energy – fossil, most probably. That’s almost half of the electricity the plant produces.
The Ductor process, combined with a biogas plant, can turn the 485,000 tons of poultry litter into renewable electricity (210,000 MWh), thermal energy (233,000 MWh), and a liquid nitrogen fertilizer (39,000 tons), plus a solid organic potassium-phosphor fertilizer (208,000 tons).
So, why burn poultry litter?
Before Ductor, it was impossible to use large amounts of poultry litter in biogas production, because the nitrogen in the poultry litter would turn into ammonia which, even though it’s already at a low concentration, stops biogas formation. But Ductor changed that. Our patented microbes convert the nitrogen in poultry litter (and many other organic materials) into a separable form before the litter enters into biogas production. It also separates it as ammonium salt. As a result, there is no possibility of ammonia inhibition in the biogas process.
The result? No more releasing nitrogen into the atmosphere and therefore no use of energy to catch it again from there.
And instead of ash, the potassium-phosphor fertilizer is in the form of dried pellets with some organic carbon. It’s a much more soil-friendly product. This is recycling of nutrients.
Will the biological route be more expensive than the burning route? According to the article I read, that plant in the Netherlands cost around €210 million, the equivalent of €5,750 per kW of electrical power. The biological route will be €5,300 per kW of electrical power. Instead of one huge plant there could be many smaller biogas plants, as it seems that the logistical optimum is well below 36.5 MW.
So burn it no more!