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Fuel cell basics

Hydrogen atoms enter a fuel cell at the anode where a chemical reaction strips them of their electrons. The hydrogen atoms are now 'ionized', and carry a positive electrical charge. The negatively charged electrons provide the current through wires to do work. Oxygen enters the fuel cell at the cathode and it there combines with electrons returning from the electrical circuit and hydrogen ions that have traveled through the electrolyte from the anode.

The electrolyte plays a key role. It must permit only the appropriate ions to pass between the anode and cathode. If free electrons or other substances could travel through the electrolyte, they would disrupt the chemical reaction. Whether they combine at anode or cathode, together hydrogen and oxygen form water, which drains from the cell. As long as a fuel cell is supplied with hydrogen and oxygen, it will generate electricity very efficiently.

History

Ask when we first began to hear about the uses a fuel cell might be put to and you'll usually hear about spacecraft or for transportation some way into the future. Ask when and where they were first invented and you will probably get estimates of around the early 1960s and at NASA. Not so. The inventor was one William Grove, an 1832 classics graduate of my alma mater - Brasenose College, Oxford.

In 1839-1842, Grove developed the first fuel cells (which he called the gas voltaic battery), and which produced electrical energy by combining hydrogen and oxygen. In developing the cell he showed that steam could be disassociated into oxygen and hydrogen, and the process reversed. The first demonstration of this effect, he gave privately to Michael Faraday, John Gassiot and Edward Brayley, his scientific editor.

Fuel cells are like conventional batteries, but batteries store electical energy whilst fuel cells produce it continuously providing fuel (usually hydrogen) and air are provided.





Hyundai ix35 now as an FCEV
1,000 for testing up to 2013 then at least 10,000 a year




I believe that water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable.
Jules Verne: The Mysterious Island

Meanwhile PetroSA is considering plans to build a R3.5billion liquefied natural gas (LNG) terminal in Mossel Bay to sustain its gas to liquids (GTL) plant that produces diesel and petrol. GTL emits around 25% more GHG's than even conventional oil refining. Haven't they heard that the world has to leave the vast majority of its fossil fuels in the ground to avoid catastrophic climate change?

 


Fuel Cells - Part 1

from Ian Perrin - 10th December 2012.

Sudden fluctuations in Germany's power grid caused damage at Hydro Aluminium in Hamburg last September when a sensitive monitor detected a drop in the voltage which lasted just a millisecond. Production stopped so quickly that the aluminum belts of the rolling mill snagged and hit machines, causing more than R100,000 damage. Twice more in the next 3 weeks the voltage weakened. Hydro is investing R1.3M to provide backup power and so protect itself from future problems. Industry is warning the German government that companies might be forced to leave if it doesn't deal with the issues fast.

The problem lies in the complexity of balancing renewable power loads when they form a large percentage of the total generating power. Four German states have 43% or more of their grid electricity dependent on wind power. The UK, however, cheered the fact that wind farm contributions broke their record 3 hours erlier in the same wind pattern as the one that damaged Hydro. The EU's 2020 target is 32% renewable energy in the UK. Of course, better load balancing, more storage and a broader European network may ease the problems by then, but SA would be wise to trail the US and EU by a few years in its adaptation to renewables. Is there another way forward? Yes - hydrogen fuel cells.

Green Hydrogen and its costs
Hydrogen is the 3rd most prolific element on earth and using it in a fuel cell produces virtually no greenhouse gases (GHGs). But to extract it and purify it is not so straightforward. Currently, it is usually made from natural gas. But that's a fossil fuel and so the life-cycle process produces GHGs.

We can extract hydrogen from water by electrolysis, which works like a reverse form of a fuel cell - water is split into its constituents (oxygen and hydrogen) by passing electricity through a cell. At first sight this may seem crazy. Take electricity, make hydrogen and use that to make less electricity than you started with. But remember that you can buy electricity at off-peak times much cheaper than at peak times. So, you can use cheap power and store the hydrogen you produce, then use that at peak times. Electrolysis and fuel cells become a way of storing electricity and much more efficiently than pumped storage of water. Since you can switch fuel cells on and off rapidly, this also becomes a way of balancing the grid and we can begin to see how the 'German' problem can be overcome. Wind and solar power paired with storage could power the grid 99.9 percent of the time.

Or you can store hydrogen and use it to power transportation. Now we have a green energy system that can be used to power our transport fleet. The electrolysis process can be housed in a standard 40-foot container. Currently that will produce enough hydrogen to fill around 100 vehicles a day, all with a range of more than 500Km. and taking less than 5min. to fill.



Can the Fuel Cell provide an alternative to the Internal Combustion Engine (ICE)?
The U.S. Department of Energy’s (DoE’s) National Renewable Energy Laboratory (NREL) recently completed a seven-year project to demonstrate and evaluate hydrogen fuel cell electric vehicles (FCEVs) and hydrogen fueling infrastructure in real-world settings. The project results show that fuel cell electric vehicles have advanced rapidly, and most vehicle manufacturers will introduce FCEVs to the market within 2 or 3 years.

First we have to get the cost of the cell in the vehicle down. Fuel cell system costs have decreased significantly over the past several years, from R2,150 per kW in 2002 to R365/kW in 2010 and are in sight of the US DoE's cost goal of R260/kW for 2015.

On the horizon is the use of carbon nanotubes instead of platinum in the cell's catalyst. Should that or other replacement materials come to fruition, the 2015 target will be met.


Next in line is the need to increase the lifetime of the fuel cell stack. Progress here is also rapid. From 46,000 km. in 2006 to 120,000 km. in 2010. But that needs to be doubled to reach the DoE's target.

A UK company, ITM Power seems to be well on the way to achieving both these targets

NREL tells us that "...there is optimism that manufacturers will introduce FCEVs to the market within the next few years." In fact most of the automotive industry is planning to introduce FCEVs by 2015, some of them in limited numbers during 2013.

So, what does all this mean for the South African transportation industry?
It is unlikely that SA will begin by manufacturing fuel cells and the equipment to produce and distribute the fuel. We have very little experience in that technology. Much more likely is that we will import it. But within a few years, I would expect manufacturing under licence would provide thousands of green jobs.

Since the infrastructure must be built from scratch, the first users will be fleet operators with denser distribution patterns. Government incentive schemes will be needed to aid the penetration of hydrogen as a fuel and allow us to reach our greenhouse gas (GHG) reduction targets. Transportation currently produces 27% of our GHGs. In the USA Shell is providing its own incentives by giving free refills. Remember, too, that 'gas' in the USA costs the motorist around R7 per litre, so being a competitor to it is harder there.

In summary:
·
Hydrogen fuel cell technology is on target to match ICE petrol and diesel engines within a few years.
· You will see announcements of new models using its technology from the automotive industry.
· Market penetration will be small to begin with, but grow rapidly.

The next part of our fuel cell story will highlight an imaginative project to trial hydrogen fuel cells integrated with clean renewable energy.


Sources : ITM Power. Energy Storage - The case for hydrogen
US DoE - www.fueleconomy.gov
DoE/NREL - http://www.nrel.gov/news/press/2012/1975.html


 
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