Hydrogen Snake Oil – Part 1 – Making Hydrogen.
As it was with the snake oil salesmen, and often is with our politicians, we are being sold a bill of goods, and a panacea solution to a very real problem. The problem is our insatiable thirst for energy, and the solution is The “Hydrogen Economy”. While it is being sold as a “futuristic way” to solve our energy problems, I am going to offer my opinion here that it is deflecting our vision and efforts from more serious and realistic goals.
Hydrogen as a transportation fuel is fraught with technical problems. Serious and debilitating problems …..
The first problem is that hydrogen is NOT a fuel at all. It is an energy carrier, the same as electricity. For every watt, BTU, Joule, or gigadyne that we get out of hydrogen, we have to put at least that much into it. And, since in the real world of physics there is no free lunch, we actually have to put in much more.
Free hydrogen does not exist on this planet. We cannot drill for it, mine it, or make a magic box that will spit out limitless amounts of it. We have to manufacture it. This is not a trivial task. Hydrogen has an affinity for just about everything. It binds to carbon to create hydrocarbons – our fossil fuels, and it binds with oxygen to create water – the substance of life. In order to manufacture it we have to break those bonds – and then, akin to keeping a pack of wolves separated - we have to keep it from re-bonding with what it likes until we can use it. So, we will stop calling hydrogen the “fuel” of the future. If anything, it is the energy distribution system of the future, although I seriously doubt that.
This essay will be in four parts. The first part will look at how we manufacture hydrogen, the second will explore how we transport and store it, and some of the challenges that entails. I will devote the entire third part to using hydrogen in our vehicles. Finally, in part 4, I will explore what is really behind this deception, (did I mention money?), describe the one or two, utopian, scenarios where hydrogen COULD be a viable energy carrier, and take a brief look at the state of the hydrogen art today.
There are currently two major ways to manufacture hydrogen today. The first is via that again futuristic sounding process “electrolysis”. It is really simple, you may have done it in a science class. Many more are doing it to generate small amounts of hydrogen, and large amounts of cash. We take water, pass an electric current through it, and out comes hydrogen at one end, and oxygen at the other. It IS that simple.
But, wait, did I mention “pass an electric current”? Therein lies the rub. We need an electric current. A large electric current. Ignoring a little bit of heat energy we need, we also have to input at least as much energy (BTUs) in the form of electricity into the process, as there will be energy contained in the hydrogen that comes out. In fact, in actual practice, the most efficient processes operate at about 70% efficiency. So, we have to input 30% more energy than we get out. So here is our real world, 70% efficient formula for getting hydrogen from electrolysis.
Water – plus - 48 Kilowatt-hours (KWh) of electricity = 1 Kilogram of hydrogen and .5kg of oxygen.
Let’s put that in perspective. 1 Kilogram of hydrogen is 11.1 Cubic Meters (392 Cubic Feet) at atmospheric pressure. That amount of Hydrogen contains 125,000 BTUs – About the same as a gallon of gas. About the same as 37KWh of electricity. We put 164,000 BTUs into this process via electricity. We recovered 125,000 BTUs out. What we have done, so far, is to WASTE 11 KWh of electricity to manufacture a substance that contains the same energy as one gallon of gasoline. A substance that takes up over 3000 times as much space as that gasoline, and, a substance that still has to be distributed, stored, and used in some way to power a vehicle, complete with many more significant losses along the way. And that is with a very efficient form of the process. Many electrolysis cells only obtain 50-60% efficiency.
Consider briefly, that same 48KWh of electricity, applied to a current, viable, production EV like, say, the Tesla Roadster (at .217 KWh/mile) will take you about 221 miles down the road. In style, comfort and at a high level of performance. How does Hydrogen compare in a vehicle? Well, we will address that thoroughly in part 3. Hint – not very well… But, back to our supply discussion.
The fact is that electrolysis, in addition to it’s energy losses, is not a cost efficient way to create hydrogen.
Because of this, virtually all the industrial and commercial hydrogen in this country, and in the world, is created by another process. Steam reformation of natural gas (Specifically the methane that constitutes 80-95% of natural gas).
Did I say Natural Gas? Why yes. The most common and cost effective way to manufacture hydrogen is by converting a fossil fuel. A non-renewable hydrocarbon resource.
It turns out, if you heat natural gas to a hot enough temperature, and pass it through a catalyst, the chemical bonds holding the hydrogen and carbon together are broken. We get hydrogen out one end, and carbon, in the form of both carbon monoxide and carbon dioxide, out the other. The heat is about 900-1000 degrees Celsius, that’s 1800 degrees Fahrenheit for us Americans. The catalyst is a precious metal, like platnium.
If you remember, all the energy we hope to eventually get from our hydrogen has to be put into it to “make” it. Plus a little – actually a lot – more to allow for the process losses. The energy we put into the steam reformation process is primarily the BTU (energy) content of the natural gas feedstock.
In addition to the natural gas, we also need the afore-mentioned heat, to make steam, to make the process work. Well, fortunately, a steam reformation process can make use of waste energy (energy not put into the hydrogen) to make that heat, improving the overall efficiency of the process from poor, to sort of good.
And, just what is that efficiency? For a typical large SMR (Steam Methane Reforming), the energy efficiency is quite high – 80-87%. Of course, throw in extensive maintenance requirements, the regular replacement of expensive catalyst material, and a little bit of electricity to run all the pumps and compressors, and the economic efficiency suffers quite a bit. But, in our non-economic model , we don’t care about that. So, here is the result from an actual plant:
We put in 141 Cubic Feet of Natural Gas, we get out our 1 Kilogram of Hydrogen. 144,000 BTUs of natural gas in, 125,000 BTUs of hydrogen out. MUCH better than electrolysis – which is one reason this is the preferred method.
(Of course, we could have just burned that Natural gas in an existing Natural Gas Vehicle and saved the losses, but again, that is for part 3… Sorry.)
But, wait, there’s more. Remember I mentioned one of the products was carbon? Well, since we started with a hydrocarbon (natural gas), if we take out the hydrogen, we are left with the carbon as a byproduct. Indeed, steam reformation produces the same amount of carbon emissions as would have happened had we just burned the natural gas. So, Will Robinson, we have another problem, one of the ones we have been trying to eliminate with all this alternative energy stuff – Carbon emissions. To be fair, they are much easier to trap and sequester here than in, say, a coal burning power plant. But deal with them we must. More cost, complexity, and another hit on hydrogen’s ever-poorer performance.
Just a short word about Steam reformation in a sensible recent quote from the US DOE (energy.gov)
“DOE is not funding research activities for large-scale central production of hydrogen from natural gas. DOE efforts are focused on distributed natural gas reforming for the transition period only. Large-scale hydrogen production from natural gas reforming is a mature technology, and natural gas resources in the United States are limited—15% of the natural gas we use is imported. Producing large amounts of hydrogen from natural gas in the long term would only trade U.S. dependence on imported oil for U.S. dependence on imported natural gas.”
I also would like to point out that, to my knowledge, all of the ballyhooed methods of producing hydrogen from things such as biofuels, or biomass, depend on steam methane reformation as described above.
There are a couple more exotic ways to create hydrogen. But, no matter the method, the basic laws of physics say we not only have to put as much energy into it as we get out, but, because no process is perfect, we have to put in more. Believe me, there are no “magic boxes”. magic catalysts, or free energy processes. Indeed, if there were, they would violate a number of fundamental laws of physics and thermodynamics. While some might argue – well we don’t know everything (and they would certainly be right) these are BASIC, well proven and accepted laws of science. The chances are mighty slim.
And, so finally, I do want to mention one other way that we can conceivably produce hydrogen. Coal Gasification.
The first thing we do is make syngas (town gas) from coal. We do that by injecting oxygen and water into a reactor (the gasifier) under high heat and pressure. The output of this reaction is a mixture of carbon monoxide and hydrogen (the syngas). We can then put that gas through the same reformation process as above and get hydrogen and carbon dioxide out. Yes, it produces nearly the same amount of CO2 as if we had burned the coal. Amazing how these things work out.
Coal gasification is really a subject for another article. While the process is being examined for the production of syngas (and gasoline via the Fischer-Tropsch process.), it is quite controversial, and in the very earliest stages of research. This article is about hydrogen, and to my knowledge there are no serious considerations of making transportation hydrogen from this process. It is dirty, inefficient, produces a number of toxins, and is still using a non-renewable fossil fuel (that, incidentally, we rely on heavily for our electricity).
I will write that article soon. In the meantime, here is a link to more information on Coal Gasification:
http://en.wikipedia.org/wiki/Coal_gasification
That’s it for part one. Stay tuned in the upcoming week or two for parts 2, 3 and 4. There is much more to cover, and many, many, more challenges facing that hydrogen economy. We have just scratched the surface.
I know you can’t wait.
Reference conversion factors;
1 Gallon = .133 Cubic Feet
1 KWh = 3414 BTUs
1 kg Hydrogen = 1.003 GGE (Gallon Gasoline Equivalent)
1 kg Hydrogen = 392 Cubic Feet at 1 atmosphere.
Tesla roadster reported energy usage is .217KWh per mile. Or 4.7 miles per KWh.
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