Last month, the DOE held its 2006 Hydrogen Program Annual Merit Review, with principal investigators presenting the status and results of the approximately 250 hydrogen and fuel cell projects funded by the DOE.
Progress is being made on many fronts, all of which were represented in the various sessions of the review: production; delivery; storage; fuel cells; technology validation; education; safety, codes and standards; analysis; and basic energy sciences. Nevertheless, key barriers remain, particularly in the application of hydrogen for the transportation sector.
|One of DOE’s major focuses is on non-platinum catalyst technologies.|
Fuel cells. Key challenges for fuel cell systems remain cost and durability, according to Valri Lightner, the Fuel Cell Systems team leader for the DOE, in the fuel-cell Plenary presentation. In overcoming those issues, there are other challenges that require focus—especially electrode performance, particularly the cathode, where the amount of precious metal catalysts on the cathode need to be reduced.
DOE studies are showing that the stack represents 70% of the cost of the fuel-cell system, and that the electrode represents almost 70% of the cost of the stack—i.e., the electrode represents almost 50% of the cost of the fuel cell system.
Another challenge is understanding the way water moves within the stack to ensure that the membranes are properly hydrated and that the water is managed in such a way during shut down that the fuel cell can start up again.
The Fuel Cell team issued a $100-million solicitation and lab call (i.e., the labs are competing with industry on the same topics) with a focus on components that closed 7 April; selections will be in the fall.
And we’ve also added a topic to look at innovative concepts. So this would be a full fuel cell system but maybe something that’s not a cell, you know, maybe it’s got a different architecture or minimizes components in some ways. So we’re really looking for some kind of breakthrough technology that can meet our future technical target.—Valri Lightner, DOE
|Transportation Fuel Cell System Targets & Progress|
|(a) Based on 500,000 units per year.|
|Characteristic||Metric||2003 status||2005 status||2015 target|
|Precious Metal Loading||g/kW (rated)||<2.0||1.1||0.2|
|Lifetime (durability w/ cycling)||hr||N/A||~1,000||5,000|
|Start-up time to 50% rated power at|
|-20° C ambient||sec||120||20||30|
|+20° C ambient||sec||60||<10||5|
|Start-up and shut-down energy at|
|-20° C ambient||MJ||na||7.5||5|
|+20° C ambient||MJ||na||na||1|
|All current approaches to hydrogen storage are far from hitting the target requirements.|
Storage. Storage remains one of the critical barriers to realizing a hydrogen-fueled transportation system, and current storage systems are not meeting the DOE’s specifications of 6 wt% and 1.5 kWh/L by 2010.
The target is a system target, not just a materials target. In other words, the weight of the entire storage system (tank, support materials) is used as the basis for calculating the gravimetric density of the hydrogen. The capability of the material alone will have to be higher to meet the system target.
Neither high-pressure gaseous hydrogen nor liquid hydrogen—by themselves, not even with the context of the storage system—will meet the target, according to Sunita Satyapal, DOE’s Storage team leader.
So what our program is looking at really is material-based technologies for the long-term.—Sunita Satyapal, DOE
The work is focused in three primary areas—metal hydrides, chemical hydrides, and carbon/sorbents—each with different pros and cons.
So in summary, our message is that new materials and concepts are critical at this early stage. We’d like to ask the researchers to ensure that you address volumetric capacity as well, temperature, pressure, kinetics, not just weight percent anymore. Basic science is essential. We need to develop a fundamental understanding that complements the applied programs. We also need to keep an eye on engineering issues, right from the start. And these are just some examples of essential capabilities that we’re in the process of developing and we need to continue to develop as we move forward.—Sunita Satyapal
All presentations are available on the 2006 Merit Review website, as well as a transcript and webcast of the Plenary session.