Method for the production of electrical energy from ammonium
The invention provides a method for the production of electrical energy from an ammonium (NH 4 + ) containing aqueous liquid comprising (a) separating at least part of the ammonium as ammonium salt or concentrated ammonium salt comprising solution from the ammonium containing aqueous liquid, (b) decomposing at least part of the ammonium salt or salt solution into an ammonia (NH 3 ) comprising gas and one or more other decomposition products, and (c) feeding at least part of the ammonia comprising gas to an fuel cell.
1. A method for the production of electrical energy from an ammonium (NH 4 + ) containing aqueous liquid comprising:
a. separating from the ammonium containing aqueous liquid at least part of the ammonium as (i) ammonium salt or (ii) concentrated ammonium salt comprising solution;
b. decomposing at least part of the ammonium salt into an ammonia (NH 3 ) comprising gas and one or more other decomposition products;
c. feeding at least part of the ammonia comprising gas to a solid oxide fuel cell (SOFC).
2. The method according to claim 1 , wherein the ammonium containing aqueous liquid is a waste stream.
3. The method according to claim 2 , wherein the waste stream comprises an effluent of an anaerobic digester, a stripper water from anaerobic sections of biological phosphor-removing waste water treatment plant (wwtp), a concentrate or filtrate stream from a dewatering section of a biological waste water treatment plant (wwtp), a (concentrated) urine containing liquid or filtrate, condensate or other liquid waste streams from digesters, or stripper units.
4. The method according to claim 1 , wherein the ammonium containing aqueous liquid is obtainable by (i) providing ammonia containing air from an animal accommodation to a liquid comprising acid, and/or (ii) providing ammonia containing off-gas from industrial emission to a liquid comprising acid.
5. The method according to claim 1 , comprising:
a. crystallizing at least part of the available ammonium from the liquid into an ammonium salt and separating at least part of the ammonium as ammonium salt from the liquid;
b. decomposing at least part of the ammonium salt into ammonia and one or more other decomposition products;
c. feeding at least part of the ammonia to a fuel cell.
6. The method according to claim 5 , wherein crystallization is achieved by adding phosphate, optionally with one or more of an alkaline earth cation, to the ammonium containing aqueous liquid.
7. The method according to claim 6 , wherein the earth cation is magnesium.
8. The method according to claim 5 , wherein the decomposition is a thermal decomposition and/or a chemical decomposition.
9. The method according to claim 5 , comprising crystallizing at least part of the available ammonium from the liquid into magnesium ammonium phosphate (MAP) or potassium ammonium phosphate (KAP).
10. The method according to claim 5 , wherein crystallization is induced by controlling the pH and temperature of the ammonium containing aqueous liquid.
11. The method according to claim 1 , wherein before feeding the ammonia comprising gas to the fuel cell the ammonia comprising gas is purified by drying.
12. The method according to claim 1 , wherein at least part of the one or more other decomposition products is returned to crystallize at least part of the available ammonium.
13. The method according to claim 1 , wherein simultaneously or sequentially ammonia and another fuel, or a mixture of these two are fed to the fuel cell, wherein the other fuel comprises one or more fuels selected from the group consisting of syngas, hydrogen and methane.
14. The method according to claim 1 , wherein ammonia and biogas are fed to the fuel cell.
15. An apparatus for the production of electrical energy from an ammonium containing aqueous liquid comprising:
a. a separator unit arranged to separate at least part of the ammonium as (i) ammonium salt or (ii) concentrated ammonium salt comprising solution from the ammonium containing aqueous liquid;
b. a decomposition unit, arranged downstream of the separator unit, and arranged to decompose at least part of the ammonium salt into ammonia and one or more other decomposition products;
c. a solid oxide fuel cell (SOFC), arranged downstream of the decomposition unit, and arranged to be fed with at least part of the ammonia from the decomposition unit.
16. The apparatus according to claim 15 , further comprising a crystallization unit, arranged to crystallize at least part from the available ammonium from the liquid into an ammonium salt.
17. The apparatus according to claim 16 , wherein the crystallization unit is a fluid bed crystallizer or a slurry crystallizer.
18. The apparatus according to claim 16 , wherein the decomposition unit is a thermal decomposition unit.