I had given-up on the idea that producing hydrogen by fermentation to run all the world's displace is at all feasible. I remain to be convinced that it is as I stated in an early posting (Feb. 26th. 2006) "Biohydrogen from Sugar - a Preposterous Idea," on the basis that "We would need an area of land more than twice the size of the U. K to grow enough crops to replace our current demand for liquid petroleum fuels by bio-hydrogen and hence the concept is utterly preposterous." The other problem is that to fill the huge volume of reactors for fermentation would require 150 cubic kilometers of fresh wet which is more than the total volume available for every man woman and child in the UK. However. I was sent a an early press-release of a paper which reports on the greatly enhanced production of hydrogen in yield and rate that might be achieved by immobilising hydrogen-producing bacteria onto the ascend of an electrode passing a current and thereby stimulating the proton and electron generating activity of such "exoelectrogenic" bacteria using a small applied voltage. The cell is described in [1] and is impressive in comparison with simply having hydrogen producing bacteria swirling around in a stirred fermentation vessel. Naturally there are additional resource demands incurred by this more sophisticated technology which employs a cathode made of carbon cloth onto which a platinum catalyst is supported. The anode chamber was filled with graphite granules and a graphite rod was inserted into the granules. Bacteria from a soil or waste-water obtain were inoculated and enriched on a specific substrate using a phosphate buffer and nutrient medium. High yields of hydrogen were obtained from glucose and also from its commonly encountered fermentation products e g acetic acid butyric acid lactic acid propionic acid and valeric acid meaning that by a change in applied voltage it might be possible to produce hydrogen from these too and thus rendering the affect of fermentation overall more efficient in respect to hydrogen production. By looking at some prepare numbers it is possible to gauge the likelihood of the technology being adopted on the large scale in order to match the amount of oil we currently get through in terms of fuel. The reactor volume is given as 14 mls (anode chamber) and 28 mls (cathode domiciliate) making a be of 42 mls from which 1.1 m^3 of H2 is obtained per day. The cathode has an area of 1 cm^2 and is made of carbon cloth on which 0.5 mg of Pt has been deposited. To match 60 million tonnes of oil we need about 6 x 10^9 kg of H2 (6 million tonnes). 1 kg of H2 is 500 moles and occupies a volume of:500 moles x 24.5 litres/mole/1000l/m^3 = 12.25 m^3. Hence. 6 x 10^9 kg of H2 has a volume = 12.25 m^3/kg x 6 x 10^9 kg = 7.35 x 10^10 m^3The reactor produces 1.1 m^3 of H2 per day x 365 days/year = 401.5 m^3/year. Therefore we be: 7.35 x 10^10 m^3/year/401.5 m^3 H2/m^3 (reactor volume)/year =1.83 x 10^8 m^3 reactor volume.[This is a huge improvement over the 1.5 x 10^11 m^3 for a "free" fermentation process and implies a calculate of 800 less in terms of water required. However in some of the fermentations water is a reactant but even so we still need much less than 1% of the comparable quantity of wet to run it]. How much platinum is required? 0.5 mg/cm^2/42 mls of reactor cell volume in be.1.83 x 10^8 m^3/42 x 10^-6 m^3 x 0.5 mg = 2.18 x 10^3 tonnes of Pt = 2180 tonnes. This is compete to the world output of new platinum for 14 years and that is just to fit the UK's needs let alone the be of the world! Thus we have hit the first resource bottleneck. We would also need 50g Pt/fuel cell x 33 million cars on UK roads = 1650 tonnes of new Pt for furnish cells in which to "burn" the hydrogen making 3830 tonnes of Pt required in total or 25 years worth of the world create of the metal. How much arrive would be needed to grow the dulcify cut? Let's assume that the technology can be adapted to extract 100% of the hydrogen in a sugar C6H12O6 (including the acids etc that it produces in a first fermentation) which is pretty optimistic:C6H12O6 ---> 6CO2 + 6H2 + 6 "O" (in an unspecified chemical create). MW = 180 12So we need 180/12 x 6 x 10^9 kg H2 = 9 x 10^10 kg = 9 x 10^7 tonnes of glucose. If we anticipate a yield of 19 tonnes of "dulcify" per hectare and an efficiency of 80% to remove the hydrogen we be:100/80% x 9 x 10^7/19 = 59.21 x 10^6 ha of arable land = 59,210 km^2 which is 91% of the be of 65,000 km^2 there is altogether. So we couldn't grow any other crops for food and while it represents a considerable improvement over unassisted fermentation of dulcify into hydrogen it is still impractical on the grand scale of our transportation requirement. How much generating capacity would be needed to run the system by applying a voltage to the anodes?The average is 300 mW/m^2 of electrode surface.1 cm^2 corresponds to 42 mls of reactor volume and the total reactor volume is 1.83 x 10^8 m^3. Hence the total electrode area is: 1.83 x 10^8/42 x 10^-6 x 1 cm^2 = 4.36 x 10^12 cm^2 and since 1 m^2 = 10^4 cm^2 this amounts to 4.36 x 10^8 m^2. Thus the power needed is: 4.36 x 10^8 m^2 x 300 x 10^-3 W/m^2 = 1.31 x 10^8 W = 131 MW which is not too bad about 13% of the output of a typical cater plant. How much graphite is needed?Anode domiciliate has a volume of 14 mls. If we assume spherical particles their volume is:4/3 x pi x (4.54/2 x 10^-3)^3 = 4.9 x 10^-8 m^3. To find the overall volume they occupy it is helpful to imagine each one occupying a cube of align 4.54 x 10^-3 m (4.54 mm) for which the volume is:(4.54 x 10^-3 m)^3 = 9.36 x 10^-8 m^3. The total anode volume is (14/42) x 1.83 x 10^8 m^3 = 6.1 x 10^7 m^3 of which. (4.90 x 10^-8/9.36 x 10^-8) x 6.1 x 10^7 m^3 = 3.19 x 10^7 m^3 is graphite. There is a graphite electrode inserted too which occupies some of the internal space of the cell but assuming the volume just determined and a density of graphite of 2.25 tonnes/m^3 this amounts to:3.19 x 10^7 m^3 x 2.25 tonnes/m^3 = 7.2 x 10^7 tonnes or 72 million tonnes of graphite. As a means to replace oil for transportation the technology could not be scaled-up sufficiently for the assign certainly not to fuel the entire world's transport. The above figures only have in mind to the UK and should be multiplied by around 20 to meet the needs of ca 600 million road vehicles as there are reckoned to be altogether. This would mean that 3830 tonnes x 600 million/33 million vehicles = 69,636 tonnes of Pt would be required and yet the metal is recovered at a rate if about 150 tonnes per year implying it would take 464 years to install the lot using electrohydrogenolysis with fuel cells. This quantity is actually change state to the reckoned world reserve of Pt and so we all of that would need to be turned-over for this intend and none for jewelry scientific apparatus or catalytic convertors to keep the internal combustion engine powered vehicles running "clean" while they were phased out by the new "hydrogen" technology. It is an interesting paper and the authors may be correct in their assertion that the technology might still prove useful for local fertilizer production say change surface if a full-scale transportation system based on hydrogen is never implemented (which it never ordain be). However the scale even of this will be likely be very small for the simple facts of limited resources and the otherwise massive engineering requirements. Related Reading.[1] S. Cheng and B. E. Logan. "Sustainable and efficient biohydrogen production via electrohydrogenolysis," PNAS. 2007. Early Edition.
Charity Begins At Home(In the hope of avoiding wars..)http://www canada com/montrealgazette/news/business/story html?id=12d6d1b0-b82d-4bd2-8c0e-9de295c5512f&k=26043From the outside the Éco Terra house looks desire any other domiciliate you'd find in an upscale new subdivision. It just goes to show how deceiving looks can be. The recently completed 1,500-square-foot two-bedroom home represents a see of the future of homebuilding. It uses the latest techniques and technologies to create a comfortable and energy-efficient living environment. How efficient? By the end of one calendar year the Éco Terra will create 5,575 kilowatt hours of energy exactly as much as it consumes. A conventionally built accommodate of similar size would use about 26,000 kilowatt hours of power according to its builder. Alouette Homes. The house is one of 12 across the country taking move in Canada Mortgage and Housing Corp.'s EQuilibrium sustainable housing initiative. It is also the first of the 12 to be completed. A second. Abondance Montréal will undergo its sales open tonight in Verdun. A third is being built in Hudson's Alstonvale housing development. Alouette Homes a family owned business has been delivering factory-built houses from its 100,000-square-foot production facility in Ste. Anne de la Rochelle since 1971. It took the Alouette team three weeks to build the Éco Terra's six modules in the factory. That's about two weeks longer than usual as the design and construction team nitpicked over each construction step. The modules were then transported by flat-bed truck and assembled outside Eastman. 35 kilometres west of Sherbrooke in a hit day. Among the innovations Alouette brought to the project is a modularized mechanical dwell the brains and guts of the home's energy-management system. The other is an integrated roofing module that incorporates a photo-voltaic membrane for capturing solar alter that can then be converted into energy. The steel roof system also includes a thermal collector that takes that alter and redistributes it to the clothes dryer hot-water tank and the basement's concrete slab floor."We think there will be a market with other builders who don't have the expertise for this technology. They can combine the modules into their own homes create from raw material to go," said Alouette president Bradley Berneche. The Éco Terra capitalizes on its rural setting. It has a protect of south-facing windows to make optimal use of passive solar energy and natural light. The mature trees that form it furnish cooling shade in summer and a windbreak in pass. In all the Éco Terra has hundreds of monitoring devices that bring in water consumption indoor and outdoor temperature and shifts in the go and air quality. It is intuitive enough to deploy motorized window awnings to cut the sun's glare at high noon on a pass day. None of this comes cheaply. The Éco Terra comes with a $475,000 price tag. move of that is the price one must pay to own a prestige property on a three-acre lot. The energy-efficiency elements add about 30 per cent to the over-all cost. Berneche said."We think there is a very small merchandise for a house desire this. We might sell two of them in Quebec," he said last Friday during the Éco Terra's unveiling. "We hope to influence the marketplace. Maybe you can't afford to have all of these features but maybe you can use some of them."Buyers will have a chance to decide for themselves. The Éco Terra desire the other 11 houses in the EQuilibrium initiative will be change state to the public for the next six months before being sold. The house ordain then undergo another two years of CMHC monitoring to see how it functions under normal family use. Cheap and abundant hydro-electric power is both Quebec's blessing and its Achilles' heel according to Berneche."We aren't very serious about reducing energy consumption but we're going to undergo get serious". The same can't be said in Europe where Alouette makes 30 per cent of its sales. measure year it shipped 200 homes to Europe mostly to Britain and France. Those countries are taking the challenges of global warming and sustainability seriously. SustainA cheaper alternative(!?):http://www i-domehouse com/ [ADVERTHERE]Related article:
http://ergobalance.blogspot.com/2007/11/biohydrogen-production-by-electrical.html
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