Institute for Residential Innovation Inc.


 


The SOSWEC

The SOSWEC simultaneously generates electrical power, heat, and potable water, from the mineralization (complete oxidation) of fuel in supercritical water (SCW).

The basic SOSWEC comprises a modified solid oxide fuel cell (SOFC) in which conventional gaseous or volatile liquid fuels are replaced by solid or liquid carbonaceous material (CM) dissolved in SCW. The dissolved CM undergoes a spontaneous partial transformation into compounds that are then mineralized by electrochemical oxidation ('burning') at the anode of the SOFC membrane. This reaction generates heat, free electrons (electrical power), carbon dioxide, small volumes of mineral acids, and additional water that is clear of all traces of the original fuel.


A synopsis of the Final Report on the SOSWEC feasibility study submitted to the B&MGF may be requested by emailing enquiries@IResI.org with ‘Final Report’ in the Subject line. Also provide your academic, business, or government affiliations (if any), with a word or two about why you’re interested.

The preliminary data, though sparse, are encouraging, and support the contention that the SOSWEC has the potential to provide autonomous point-of-production mineralization of excreted biomass, obviate the need for sewerage infrastructure, and contribute to the mitigation of global inequities in access to effective sanitation.

If you would like to become involved in this undertaking please note it in your email and I will contact you to discuss the possibilities.

Andrew Parfitt PhD
Founder and Acting CEO
The Institute for Residential Innovation, Inc

IResI, Inc. is a ‘not-for-profit’ R&D company, registered in the State of Delaware, USA.
A ‘for-profit’ Limited Liability Company (LLC) will undertake translational engineering for the technologies developed by IResI.



 

SOSWEC: components

Supercritical Water1 (SCW).
'Of all known liquids, water is probably the most studied and least understood'.2 The Supercritical state of water* (H2O) is as characteristically distinct as its solid (ice), liquid (water*), and gaseous (steam) states; transition into the supercritical state however does not occur until the temperature and pressure excede 374°C and 22.1MPa (3,205 psi) respectively.
SCW behaves somewhat like a dense non-polar gas; many substances that are insoluble in liquid water, such as hydrophobic hydrocarbons or the gases O2, N2, CO2, and CH4, are freely soluble in SCW; mineral salts however are not -- by 550°C their solubility has fallen dramatically; the dielectric constant of SCW has decreased from 80 to ~2, and the ionic dissociation constant from 10-14 to 10-23. SCW has little or no H-bonding, near-zero surface tension, abundant hydrated electrons, and high concentrations of reactive hydroperoxyl, hydroxyl, and hydrogen radicals3.

Biomass processing. Biomass In oxygen-free SCW is converted (reduced) to gaseous and liquid hydrocarbons4,5, and a precipitate of carbon char and mineral salts. If O2 is injected at this stage all the carbonaceous material is rapidly converted (oxidized) to CO2, H2O, and small amounts of dilute mineral acids. The oxidation reaction is highly exothermic, becomes autothermal once the biomass:water ratio exceeds ~6% w/w, and is more than 99.99% complete in less than 60 sec. at 25MPa and 600°C.

*In this document the term 'water' refers to water molecule itself regardless of its state (solid; liquid; gas; or supercritical); *in common usage however, the term 'water' generally refers to liquid water.

Insert: Lab. SOSWEC: reactor vol: 285cm3; tube vol: 18cm3


The SOFC membrane.
A microtubular ceramic membrane composed of three strongly bonded but, functionally distinct, concentric cylindrical layers. The outermost layer comprises the anode (+) and is riddled with interconnected microporous channels. The next layer is the electrolyte (E), a dense (non-porous) ceramic (compressive strength ~500-1000MPa) that conducts oxygen ions (O2-) but is impermeable to molecular oxygen (O2) and a poor conductor of free electrons. The cathode catalyzes the reduction of O2 to O2- and lines the central lumen through which air is pumped at near ambient pressure.

Both anode and electrolyte are exposed to SCW; the cathode however, being shielded by the electrolyte, is not.

Oxygen ions migrate through the electrolyte (at 450°C) driven by the transmembrane pO2 gradient5. Electrochemical oxidation of the fuel (CO and H2 derived by 'reforming' of feedstock) then occurs at the 'three phase boundaries' () on the surface of the anode, where the fuel in SCW, the nascent O2- ions, and the electron collector () co-locate.

The products of the electrochemical oxidation of biomass are (i) CO2, H2O, and a small amounts of mineral acids, (ii) free electrons, (iii) excess energy. The latter manifests partly as heat, and partly as the energy of the free electrons, which are collected and conducted through an external circuit back to the cathode where they are consumed in the production of more O2- ions.

Membrane composition:
Anode: Ni-YSZ (Yttria stabilized Zirconia); Electrolyte: YSZ; Cathode: La1-xSrxCo1-yFeyO3 on gadolinia doped ceria (x:0.0-0.4;y:0.0-1.0)

Refs:
1. J. Supercrit. Fluids; doi:10.1016/j.supflu.2008.09.007 ‘A perspective on catalysis in sub- & supercritical water’
2. Franks, F. 'Water, the unique chemical', in Vol.1, 'Water: A Comprehensive Treatise'
3. AIChE Journal; http://dx.doi.org/10.1002/aic.690430517 Fugacity Coefficients for Free Radicals in Dense Fluids: HO, in Supercritical Water

4. Biomass and Bioenergy; 10.1016/j.biombioe.2012.03.035 ‘Degradation pathways of holocellulose, lignin & á-cellulose from P. vittata fronds in sub- and super critical conditions’
5. J. Supercrit. Fluids; 10.1016/j.supflu.2012.02.031 ‘Hydrogen production from some agricultural residues by catalytic subcritical and supercritical water gasification’
6. http://www.nd.edu/~msen/Teaching/DirStudies/FuelCells.pdf

Click here for a 'printer friendly' PDF version of 'SOSWEC: the components'


Back to top

 

 

 

SOSWEC: advantages

1. General

increases the net energy yield from biomass by eliminating pre-combustion drying
extends the range of suitable biomass
simplifies the engineering required for oxidation in SCW

accepts a variety of carbonaceous feedstocks in addition to biomass
simplifies switching between fuels
enables co-combustion of multiple fuels
facile shut down and restart

1. Technical

passive delivery of oxygen ions through the SOFC membrane conserves the energy that would otherwise be used to generate and inject O2, either as a gas or as hydrogen peroxide, into the SCW.
low surface tension of SCW facilitates rapid permeation of fuel through the microchannels in the anode of the SOFC membrane
hydroxyl ions in SCW prevent carbon deposition on anode ('coking').
bulk of SCW remains relatively anoxic, thus minimizing corrosion of the SCW reactor
oxygen ions exiting the SOFC membrane react rapidly with fuel at the 'three phase boundary'.The pO2 in SCW thus remains near zero and the transmembrane pO2 gradient is maintained (see 'SOSWEC: the components').

 

Click here for a 'printer friendly' PDF version of 'THE SOSWEC: advantages

 


Back to top

 

 

 

 

SOSWEC: applications


The SOSWEC operates with two types of fuel: Biomass, and CHONS Compounds (liquids and solids composed primarily of Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur).

The Fuel Preparation Modules ensure that both types of fuel can be processed in the same SOSWEC.

Applications for the SOSWEC:

Sanitation and Water Purification
Power Generation
Multifunction


Sanitation and Water Purification

1. The Sewage Containment and Mineralization system* (SeCoM)
An autonomous, fully automated, high throughput micro-sanitation and water repurification system that discharges only climate neutral volumes of CO2. The SeCoM is the enabling device for the creation of a fully autonomous stand-alone toilet (no power input, no plumbing) suitable for 'Improved Public Facilities' (IPFs), watercraft, and residences of any type, anywhere, on or off the planet.

Power Generation

1. Micro-Generator.
Compact, lightweight, with no moving parts, it is silent, vibration-free, and with multi-fuel capability. Suitable for use as a portable generator, or as an alternative to the internal combustion engine for electrical power generation in hybrid, all-electric-drive vehicles or watercraft. Zero discharge of NOx, SOx, unburnt hydrocarbons, and carbon nanoparticles eliminates need for a catalytic converter.

2. Portable high pressure, high temperature, steam generator.

3. Combined Heat, Power (CHP), and Water Purification.

Multifunction

Suitable for micro-residences. Functions as above, but also provides hot water, steam, and hot air.

 

*Patent Pending

Click here for a 'printer friendly' PDF version of 'THE SOSWEC: applications

 


Back to top

 

 

 
 


© Institute for Residential Innovation Inc.