The development of hydrogen fuel delivery technologies is critical to the use of hydrogen as an energy carrier for transportation and stationary power. Hydrogen can be produced at centralized processing facilities and delivered in liquid, chemical, or gaseous form to fueling stations. Or, it can be produced in smaller amounts at distributed energy facilities to reduce the cost of hydrogen movement and handling.

With support from the Department of Energy's Hydrogen Program, Sandia develops system models to simulate power generation technologies that use hydrogen as an energy carrier. Researchers are currently developing a general model for distributed generation sites, called power parks, where generation is co-located with a business or an industrial facility that needs power. Power parks can be sited as a node on the electric grid in areas where local energy use or geographical factors makes an alternative energy source practical.

The DOE envisions the transition to widespread hydrogen distribution will likely begin with distributed generation of hydrogen. This eliminates the need, in the near term, for the construction of hydrogen pipelines. Instead, a distributed strategy takes advantage of existing distribution capabilities for fuels like natural gas. In addition, the cost of hydrogen produced at small-scale facilities may be reduced by combining power generation by fuel cells or engines to supply local needs.

Power parks use combinations of technologies, such as photovoltaic collectors, wind turbines, gas microturbines, and fuel cells fed by hydrogen generated by electrolysis or hydrocarbon-fueled reformers. Sandia's computer models use Simulink software to create a library of individual components for hydrogen production, storage, and utilization to generate electricity, along with components representing internal loads and electric distribution to the grid. These components are linked together to perform dynamic simulations of the power park and enable researchers to examine the thermal efficiency and cost of both hydrogen and power production.

The DOE demonstration facility in Las Vegas, Nev., is an example of a hydrogen power park.

A hydrogen generator located at the world's first hydrogen and electricity co-production facility in Las Vegas, Nev.

The hydrogen generator in the photo is designed to supply both a fuel cell stack and a vehicle refueling station. The system simulation computes the efficiency of the individual components and estimates the future cost of both hydrogen and electricity for a hybrid system of this type.

The hydrogen generator converts natural gas to hydrogen by steam reforming. A published analysis of reforming systems is available. While the maximum possible thermal efficiency for converting chemical energy stored in natural gas to hydrogen is 80%, the more practical expectation is that a system could operate at 70% efficiency.

For more information:
A. E. Lutz, R. S. Larson, J. O. Keller, "Thermodynamic comparison of fuel cells to the Carnot cycle," Int. J. Hydrogen Energy 27, 1103-1111 (2002).

A. E. Lutz, R. W. Bradshaw, J. O. Keller, D. E. Witmer, "Thermodynamic analysis of hydrogen production by steam reforming," Int. J. Hydrogen Energy 28, 159-167 (2003).

A. E. Lutz, R. W. Bradshaw, L. Bromberg, A. Rabinovich, "Thermodynamic analysis of hydrogen production by partial oxidation reforming," Int. J. Hydrogen Energy 29, 809-816 (2004).

Contact:
Andy Lutz
aelutz@sandia.gov
(925) 294-2761