Ah, so now we use solar cells to produce electricity, with which we split water atoms into oxygen and hydrogen. And then later, we burn the hydrogen to AGAIN produce electricity, which we use for all kinds of other stuff...
I\'m wondering: every conversion costs an amount of energy, causing the efficiency to drop. So why transform electricity into hydrogen, and then back again? Wouldn\'t it be smarter to just skip the last two conversions, and just store the electricity directly? What do we stand to gain from these extra conversions?
Boiling Oil, what we gain is storage capability, portability, and slow accumulation/fast release capability. I don\'t think we need to compete on overall efficiency since there is generally less impact from the inefficiencies related to hydrogen than fossil fuels.
There are concerns about catalysts and storage chemistry/release rates that do merit concern, but they must be compared to the existing fuels and their dependence on a much larger infrastructure that limits our ability to operate independently, especially during natural disasters, etc. Rational safety factors may decrease overly shortsighted, purely economic, efficiency, but that has been true with every previous energy source I can think of.
Batteries tend to be expensive to produce, dirty, and lose their efficiency over time. Efficient hydrogen production has been sought after to take the place of batteries as a storage solution. Your name says is all boiling (heating) oil or heating salt are two other methods used to store energy produced by solar at times when the sun isn\'t out. The problem with hydrogen production has been older catalysts are expensive made from platinum. This is a cheaper way to get the job done.
You don\'t burn the hydrogen Dummy!! Use it in a fuel cell... For a super clean energy source when the sun isn\'t shining.
BoilingOil: Could you give an example of a way to \'store the electricity directly\'? Maybe I\'m dumb, but it\'s not a phrase that is making any sense to me.
Surely the best way is to feed surplus energy back into the grid, which is credited to your account. You don\'t need to store it. That\'s what we do in the UK.
fatfox-I think he means batteries. That point is addressed by jimyoung and Dimitri Leontari
It would be good if multiple conversions were not required to have readily available energy. Boilingoil, you are correct in assuming that most mechanical, electrical and biological systems conform to the second law of thermodynamics in that they always tend to increase entropy (or decrease the efficiency of conversion), this tends to be especially so if multiple conversions are involved. However energy conversion problems or efficiencies are generally confined to specific input to Ã¢â‚¬Å“desiredÃ¢â‚¬Â output conversions. The trick to sustainability is to reuse every output from the conversion process to increase overall Ã¢â‚¬Å“efficiencyÃ¢â‚¬Â. For example: a CHP (Combined Heat Power Generator) that converts methane (NG) into electricity at up to 47% eff. and that reclaims the heat from the exhaust/cooling system to warm buildings, the total efficiency can be up to 90%. Now if you use a biogas system to create the methane through anaerobic digestion you can use nearly any waste organic matter (including that from landfill etc) to produce a gaseous fuel that can be stored and compressed for use in vehicles or generation, using existing Natural Gas equipment. Anaerobic digestion is a naturally occurring phenomenon that consumes organic material (or Carbohydrates) and converts them to methane (Hydrocarbons), with the only process waste being pathogen free soil improving mulch. The beauty of this process is that it rides piggy back on human consumption ie more food consumption = more organic waste. Also it uses organic (plant or animal waste) waste that is no longer fit for human consumption, unlike biodiesel, ethanol etc. But I suppose the best thing is that organic material is solar powered through photosynthesis, and plants and animals store this energy chemically, in the form of carbohydrates and fats until it can be released in the biogas system. Might seem like a lot of conversions to achieve the desired output, but along the way it produces numerous benefits to the environment and humanity.
It is my opinion that hydrogen and any of its derivatives are products of fossil fuel focused development, for the exploitation of many for the benefit of a few...in this case they are obviously 'playing' with the figures to keep their 'efficiencies' high ;)
Capacitors will do this with a relatively low energy density, a battery obviously stores the energy chemically though
Boiling Oil. Electricity is an \"instant\" thing like light. You can\'t store light by shining it into a box all day then closing the lid. A capacitor stores electrons directly but storing a significant amount is impractical. So electricity needs to be converted into something else to store it. Like chemical energy or heat.... or hydrogen.
duh! Just shovel it into a skip! XD
May 18, 2010
Dr. Nocera's work was reported in Scientific American magazine in July, 2008, along with Dr. Bjorn Winther-Jensen of Monash University in Australia. Both scientists have developed low-cost substitutes for platinum - Dr. Nocera in the dissociation of water into hydrogen and oxygen, and Dr. Winther-Jensen in developing polymer electrodes for fuel cells. There are, however, alternative methods of splitting water molecules.
Water split into hydrogen and oxygen on board a motor vehicle is possible right now, using the existing technology of photocatalysis. Photocatalysts, in the presence of light and in contact with water, dissociate water into hydrogen and oxygen. A simple gas separation system would direct the hydrogen and oxygen into a fuel cell, which will create electricity for electric motors to propel motor vehicles.
Light-emitting diodes [LEDs] emitting extreme ultraviolet wavelengths, would use battery electricity only at night or overcast days. Vehicle batteries would be recharged by excess electricity from the fuel cells, regenerative braking, household current, and solar cells on the vehicle's roof.
Water, of course, is the only portable non-carbon source of renewable fuel available in the huge quantities needed to supplant gasoline. Water requires no investment in exploration, drilling, refining, mining, transportation, service stations, or disposal of nuclear waste. Unlike carbon-based fuels, water is recyclable.
Hydrogen and oxygen also can be used in internal combustion engines that are designed to burn hydrogen; or the gases can be burned to heat boilers to create steam to drive turbines connected to electric generators in large electric generating plants, or the hydrogen can be used in stationary fuel cells to generate electricity for individual businesses or homes.
Titanium dioxide [the stuff that makes toothpaste and paint white] is a cheap and plentiful photocatalyst. Dr. Chris Sorrell at the University of New South Wales is working on water dissociation systems using titanium dioxide. (firstname.lastname@example.org) Australia has 40% of the world's supply of titanium dioxide.
In February, 2007, Dr. Manoranjan Misra of the University of Nevada/Reno, (email@example.com) announced that he had developed carbon nanotubes that dissociate water in the presence of light. He reported that: "The new power source is extremely cost-effective"
Expensive tris bipyridine ruthenium, reacting in combination with dioctadecyl or dihydrochlolesteryl esters, also dissociates water in the presence of light.
An article in the April 29, 2010 issue of Nature magazine by lead author Hemamala Karunadasa of the DOEs Lawrence Berkeley National Laboratory discusses "A molecular molybdenum-oxo catalyst for generating hydrogen from water." The catalyst can be used with clean or dirty water, or salt water, at ambient temperatures. Apparently, light is not needed to power the water dissociation.
Why are those in the U.S. Congress providing $4 billion to develop carbon sequestration technology when that will only serve to prolong our dependence on carbon fuels? In reality, Congress is pandering to the fossil fuel industries. Why is Congress not using that $4billion to develop portable, onboard water-splitting systems so that we can achieve total energy independence from fossil fuels?
to fatfox: your brain is fat-occluded with your instructors\' political bias or limited expertise. H2 from water, how did you get to co/co2, etc.? if done without loss of catalyst, and as described in this article, even if the niborate is partially \"lost\", remainder products are salvageable for recycling. i have been playing with these many various cheap compounds for about 75 years. and i think researchers are close. now go from bench/lab scale to using a swimming pool! isrealis had/have an alkaline desert salt pond functioning many years ago. i cannot find file, and illness interrupted my project and contacts. OldeAlchemist.
If this can be made to work at utility scale, it could be a revolutionary development. Unfortunately, it would only solve half of the hydrogen problem. The other half is storage and transport. Hydrogen has low energy density by volume. Even in its densest liquified form, liter for liter, it can\'t match gasoline or any other hydrocarbon for energy density, and cryogenic liquefaction takes a lot of energy. Adsorption media like metal hydrides and activated carbon have been researched for years, but they\'re either heavy, expensive and/or just haven\'t worked out.
@Fatfox and Warren52nz: Last time I checked, batteries had already been invented... And from what I was told, these things store.... eerrrhm.... ELECTRICITY! That\'s it!
(sorry for the sarcasm... nasty habit I have)
Give it up. Batteries have too many drawbacks to be used on the utility level. They\'re very expensive for each kWH of capacity. The battery pack for one electric car costs tens of thousands of dollars. You\'d need a million times that capacity for a small city. Batteries would need space between them for cooling, since all batteries heat up during charging and discharging. They degrade over time, so they\'d need to be tested and replaced. If one cell in a large bank of batteries fails catastrophically, it can damage quite a few more. Have you seen the videos of flaming laptops? And yes, even batteries waste some electricity as they charge. That\'s the law of the universe for you. No process is perfect. There are always some losses. Because if you really think about it, you\'re not \"storing electricity directly\" in a battery when you recharge it. You\'re using electricity to reactivate the anode and cathode. It\'s a chemical reaction. Then when you need it, the electrolyte in the battery allows ions to migrate from one electrode to another, moving electrons in the process. Again, a chemical reaction. You\'re not storing electrons directly.
@ Spirit of 76 Boilingoil
Technically you are correct in your assumption that batteries (whatever type) are expensive and unlikely to be used at a utility scale. However economically this is not quite true. Firstly the overall price reduction in batteries, in particular that of LiFePo4 cells in recent years, has significantly improved their feasibility. The biggest development though is that of brilliant Shai Agassi (http://en.wikipedia.org/wiki/Better_Place) who envisages utilizing battery capacity from electric vehicles to support peak power, whilst only consuming off-peak power for charging. This smoothing effect between the two rates (ie buying at $30MWh off-peak, and selling at $300Mwh peak) can produce a substantial profit, especially if you consider that the vehicle owners are effectively paying for the batteries through their vehicle purchase. Other benefits include: intelligent network capacity buffering, physical demand following capacity (ie vehicles are charged at home and then driven to work with excess capacity, which then provides extra capacity to the company at which the person works (according to the current MWh rate), with enough reserves to drive home), greater renewable energy penetration through the ability to store intermittent generators like wind and solar, and a better utilization of base load generators. My point is that any system that exploits the economic principle of high demand/low supply=high price and low demand/high supply= low price can be economically profitable even if the capital cost of the system is exponentially higher than conventional systems. The ability to incorporate private transportation into a utility scale \'consumption buffer\' system should be common sense, seeing that there is about 10 times as much energy conversion capacity in vehicles (ie engines), then there is in electricity generation, and most of that conversion capacity is wasted because it is standing around doing nothing...or otherwise known as \'parked\'. Its about time we start to fully utilize all of our resources (ie increase our overall efficiency) throughout all of our systems, to produce a sustainable future. PS see my comment further up this column.
can also store energy as potential energy. E.g. pump water into a reservoir, then let the water back down again driving a turbine on the way to convert the potential energy to electricity.
Not sure what the efficiency would be, but it\'s at least basically clean.
Another form of energy storage that is showing significant promise is flywheels, but not the kind or size you may be familiar with related to car motors and such. Giant flywheels are being developed which will reside below ground, rest on magnetic bearings, and be contained inside a vacuum for near 0 resistance in the form of friction.
These flywheels can store massive amounts of energy by being \"spun up\" using motors over long periods at low rates while the energy is available (i.e. during sunlight), and then be \"tapped\" to reverse the process, using the inertia in the flywheel by spinning the same motors/generators to generate the electricity.
The fact is there are many ways to store, but i think JimYoung said it well earlier...storage capability (or capacity), slow accumulation, fast release capability (to meet high demands quickly), and portability are the main goals (though there are a myriad of other goals). In the case of flywheels, obviously we lose portability, but flywheels excel in several other aspects. Hydrogen on the other hand excels in portability, but it\'s sheer volume, weight, and difficulty to store and release safely and quickly both limits portability and also limits capacity.
I believe the best solution in many cases, is a combination of solutions. Perhaps we\'ll be utilizing some solutions or combinations of solutions for our portable needs (such as Hydrogen, Fuel Cells, Methane, and even smaller flywheels, etc.), whereas others (such as combinations of flywheels, heated salt, and water storage reservoirs, etc.) will be the storage method of choice for power grids and such. Each may not only be a more appropriate solution for its respective application due to size and portability (or lack thereof), but as in photovoltaic solar \"hot cells\", further benefit from secondary collection of heat converted into electricity to increase efficiency dramatically.
Whatever the solution(s), it\'s clear we are finally beginning to put our minds together as a global human race to seek these solutions with the right purposes in mind, renewable energy, green benefits, low carbon impact, and freedom from fossil fuel.
I applaud all attempts to thing outside the box on these fronts.
The elephant in this room is potable water is on the decline. Fracking has only made it worse. Also, a good read is Cadillac Desert by Marc Reisner.