From the infrastructure, to transportation, to the smart home, and mobile devices, fuel cells will play a big role in the IoE.
There is no arguing with the fact that civilization is consuming power like never before. Even with a growing awareness of energy conservation at all levels, and across all types of platforms the world’s appetite for energy is growing, logarithmically. And technology is not going to be able to make conventional energy sources efficient, and earth-friendly enough to supply all that will be needed.
As the IoE evolves, there will be a huge increase in the number of powered devices – in the tens of billions, and eventually hundreds of billions, of devices. Of course, some of them will be legacy devices that will join the IoE without changing their power footprint. But there will be many new devices, which because they are devices on the IoE, can be designed to use green and alternative power sources. Even the simplest of devices with two-way communications will require a power source.
These devices will have a variety of power options to choose from. Some can use solar or wind. Some electricity from the grid. Others are prime candidates for emerging technologies such as energy harvesting or fuel cells. However, while some of the energy sources leave little, or no carbon footprint, others such as fossil fuels leave a huge carbon footprint. And many of the devices that use fossil fuels are perfect candidates for fuel cell power plants of one sort or another.
To address this, science and technology have been hard at work looking at existing platforms and developing alternative technologies that will both meet the energy demand and be earth-friendly. In some areas, such as solar and wind, the curve is at the knee. They are relatively mature and any progress in these area is generally incremental. But for other areas, such as energy harvesting and fuel cells, the future is bright. There is a lot of potential in both of them, especially fuel cells, which is a highly scalable energy platform.
Fuel cells are not anywhere close to new, but the exciting news coming from that segment is the advancements in their technology. Technology has, and will continue to make them more economical, viable, and efficient. But their real shining star is that they have an unlimited fuel source – hydrogen, and they only spent byproduct is water. Many think that hydrogen fuel cells can radically change the future of the energy landscape.
Fuel cells 101
There are many different types of fuel cells; AFC, PEM, DMFC, MCFC, PAFC, and SOFC (see glossary of terms at bottom of story). They all operate a slightly different manner. But in broad terms, energy is produced by the hydrogen atoms entering a fuel cell at the anode, at which time a chemical reaction strips them of their electrons. The hydrogen atoms are now ionized, and proceed thought the PEM to the cathode. At the same time, the separated electrons are routed to the load, usually via wiring and provide the electricity to do work. After their journey, they combine with oxygen fed into the cell and become water.
Unfortunately, hydrogen doesn’t exist uniquely as a gas on Earth because it is lighter than air, and escapes from our atmosphere in its natural state.
But it is the most plentiful and simplest element in the universe, and on Earth it is found combined with other elements – and, those elements are plentiful.
Hydrocarbons are one example. Hydrogen molecules can be found in compounds such as gasoline, natural gas, methanol, propane, coal, and many others. Hydrogen also can be “farmed” from water and biomass, and it has been found that even some algae and bacteria emit the gas. So there is plenty of hydrogen to go around. The challenge is creating devices that can use it as fuel, cheaply, safely, and reliably, and storing it. Its main downside is its volatility, making production and storage quite challenging, especially for applications where it cannot be adequately contained. And the biggest fly in the ointment is its potential explosive nature under certain conditions.
How to make it
The basic construction of a hydrogen fuel cell is shown in Figure 1. While there are several ways to product hydrogen, the two most common are steam reforming and electrolysis. Electrolysis can not only use water, but alkaline, as well.
Hydrogen is widely used for many different products so methodologies for farming it are fairly well understood, and mature. Therefore, once fuel cells become economical, and the technical hurdles for mass deployment are overcome, hydrogen-powered engines will radically alter the power landscape.
Much of the today’s hydrogen comes from within the CPI, where steam reforming is the most predominant technique of producing Hydrogen. There are two methods within this technology, SMR and SNR.
SMR works by the combining methane and steam. SNR works similarly, but only SMR is shown. Using high temperatures, and moderate pressures, steam and methane (or naphtha) are combined in catalyst-filled tubes where they generate a synthesis gas. Steam and hydrocarbon enter the reactor as feedstock, and hydrogen and carbon dioxide are generated at the end of the process. The endothermic chemical reactions for the methane compound are represented by:
These reactions produce hydrogen, which is then captured. There are other criteria to sustain the reaction, such as heat, as well.
Electrolysis is the second major method for generation hydrogen gas. Water and alkaline are similar, so the water method is presented. This method passes an electric current through water, which produces the hydrogen by splitting water molecules via a reaction process.
How this works is that current enters the electrolysis device through the cathode, is passed through the water the anode. This process evolves hydrogen, which is then collected at the cathode. The oxygen that is generated is collected at the anode. It is a relatively simple reaction given by:
Essentially, fuel cells generate electricity much like batteries, from an internal chemical reaction. However, unlike batteries, there are special requirements for containment, handling and safety.
But most batteries in commercial use have a low probability of exploding. Hydrogen is much more volatile. That is not to say batteries are, impervious to explosion, and fires (especially lithium), but such incidents almost always occur under abuse conditions. With hydrogen, the potential for explosion is inherent and can occur under normal conditions because hydrogen gives up its electrons very easily. While hydrogen itself is a fairly stable molecule, it has the propensity to react with many different types of elements to form a variety of compounds. And that is where the problem lies.
Actually, hydrogen burns rather than explodes when oxygen and any ignition source is present, however minute. Obviously, with the ubiquity of oxygen and potential ignition sources, the problem is self-evident. And this is the major challenge that hydrogen power plants have to overcome, especially if they are going to be used in open environments, such as smart homes, vehicles and mobile devices from wearables to communicators.
Progress is being made, however, but large-scale integration of fuel cells in wide variety of devices is still several years off.
Scaling down; scaling up
One of the nice things about fuel cells is that they scale well, from milliwatts to megawatts. Back in 2008, Toshiba presented an actual working prototype of a cell phone that utilized the DFMC technology.
And late last year a British-based company, called Intelligent Energy, unveiled an iPhone 6 powered by a hydrogen fuel cell. The cell is so thin it can fit it to the existing chassis without alterations, and retaining the rechargeable battery. Preliminary specs show that it can run for an entire week. To “recharge” one simply adding hydrogen from a cartridge – instant charge up. The only noticeable difference from the standard version are the addition of some vents to allow the water vapor to escape. On the charger side the company also offers a hydrogen-powered iPhone charger called “Upp,” based on the same technology.
Imagine, in the near future, all one has to do to recharge their cell phone is to carry a small cartridge, or, perhaps, hook up to a public hydrogen refill station, pay a recharge fee, connect a hose and instantly the phone has a full charge. And, why stop there, this can be stratified across any number of portable device, including wearables.
Scaling up a notch, another British-based company, Arcola Energy, offers fuel cell developer kits to interested parties. Their inventory includes kits designs for homes, to transportation.
Going up, the world’s largest fuel cell park is in South Korea. The plant consists of 21 2.8 MW hydrogen fuel cells for an output capacity 59 MW.
So the potential for using fuel cells can be seen across virtually every power landscape – from smart phones to smart cities.
One of the changes the IoE will bring will be the deployment of the Internet of energy. Fuel cells will play a large role in the storage of energy, along with batteries, wind turbines, solar, energy harvesting, and traditional power sources. But, fuel cells along with the renewable or “free” energy sources will become one of the more prominent sources of energy for the IoE.
That is because fuel cells are very “green.” Fuel cells do not burn anything and have no direct carbon footprint. They are silent and mechanically simple. However, how the hydrogen is derived does have a carbon footprint, and the manufacturing of them has an up-front impact. Moreover, they do produce carbon dioxide. But compared to fossil fuels, and most battery technologies (which eventually end up in the refuse pile), they are as perfect a power source as is solar, and wind.
For objects of the IoE, such as smart phones and tablets, wearables, medical devices, sensors, smart homes and the like, fuel cells are lining up to become a viable energy source.
But they’re still not quite there yet. One of the most challenging issues is how to make hydrogen both cheap and conveniently available. Considering hydrogen’s volatility, that is a major challenge.
Storage is another challenge. Hydrogen is difficult to store in its quiescent state because it has such low density. Today it is generally stored in an altered state such as a cryogenic liquid or as a pressurized gas. However, one promising storage method that is being investigated is nanostructured carbons, which preliminarily show promise in storing large amounts of hydrogen at near room temperatures.
Another challenge is durability and reliability. Progress has been made, but temperature extremes, especially sub-zero conditions, affect the state of the water in the systems. The other aspect of this is that the purity of oxygen and hydrogen affect the efficiency of the system.
And, finally, there is the cost issue. While some progress has been made in getting fuel cell systems to be economically viable across a girth of applications, with the exception of vehicles and power plants, the costs are still too high to make them viable.
Fuel cells have been the touted as the solution to many of our energy issues today for quite some time. From a technical perspective, they offer a number of attractive options. However, there are a number of “ifs” in the equation, most of which have been discussed here.
Nevertheless, fuel cells are coming of age. The fact that a company would make a prototype that can power a cell phone for a week has wide-ranging implications. And that others are offering developer kits is also promising.
It is difficult to predict when fuel cell technology might hit the knee so economies of scale take over and the challenges are overcome. But once they do, they have the potential to ramp up and deploy like nothing we have seen in the power arena.
Glossary of terms:
AFC – Alkaline Fuel Cell
CPI – Chemical Process Industries
DMFC – Direct Methanol Fuel Cell
MCFC – Molten Carbonate Fuel Cell
PAFC – Phosphoric Acid Fuel Cell
PEM – Proton Exchange Membrane
SMR – Steam Methane Reforming
SNR – Steam Naphtha Reforming
SOFC – Solid Oxide Fuel Cell