Direct-hydrocarbon fuel cells

Table 3 shows that the power density produced from the single chamber is at the level of the conventional double chamber for the direct hydrocarbon fuel cell. Since the fuel utilization data in these studies were not provided, it remains unclear whether the overall efficiency of the single chamber fuel cell is at the level of double chamber. 

The direct hydrocarbon fuel cell has shown a great promise for its simplicity and significant potential for further improvement in the power density. Enhancing the current density for intermediate and low temperature solid oxide fuels requires innovation in both materials development for electrode catalysts as well as fabrication approaches. 

Anode Materials for Direct Hydrocarbon Fuel Cells. 756... 

In the early days of fimdamental studies of fuel cells, great efforts were made to develop direct-hydrocarbon fuel cells ", light paraffin molecules such as propane and ethane, as well as unsaturated compounds such as ethylene were studies in this context The form in which hydrocarbons are adsorbed on platinum was the subject of controversy at the time, because it was assumed that it would influence the catalytic... 

The advantage of producing liquid hydrocarbons instead of ethanol is that it avoids the need to change the complex and costly infrastructure for fuel distribution and use (engines), and on-board (on car) or on-site (at the fuel pump) reforming to H2. With respect to this alternative it would be preferable to use directly ethanol fuel cells (see next section). 

Most fuel cells are powered by hydrogen, which can be fed to the fuel cell system directly or can be generated within the fuel cell system by reforming hydrogen-rich fuels such as methanol, ethanol, and hydrocarbon fuels. Direct methanol fuel cells (DMFCs), however, are powered by pure methanol. 

As well known, these hydrocarbon fuels are not suitable for use directly for fuel cells, even for the solid oxide fuel cell (SOFC).3 A hydrocarbon fuel processor would be required to produce a suitable fuel such as hydrogen or synthesis gas for fuel... 

A new version of MCFC technology - the direct carbon fuel cell (DCFC) - is under development at the Lawrence Livermore National Laboratory in the USA. Instead of using gaseous fuel, a slurry of finely divided carbon particles dispersed in molten alkali metal carbonates is fed to the cell. The carbon is made by the pyrolysis of almost any waste hydrocarbon e.g., petroleum coke), a process that is already carried out industrially on a large scale to produce carbon black for use in the manufacture of tyres, inks, plastic fillers, etc. The pyrolysis reaction yields hydrogen that can itself be utilized in another fuel cell ... 

An alternative to the use of H2 as fuel is methanol, which is a liquid fuel and easy to handle. This can be directly transformed to electrical current in a DMFC (direct methanol fuel cell). The DMFC allows a simple system design. However, presently achieved performance data of DMFC is not satisfactory and material costs are too high. As another alternative, methanol or hydrocarbons (e.g. natural gas, biogas) can be transformed to hydrogen on board the electric vehicle by a reformation reaction. This allows use of the H2-PEFC cell, which has a higher level of development. The reformate feed gas may contain up to 2.5% carbon monoxide (CO) by volume, which can be reduced to about 50ppm CO using a selective oxidizer (Wilkinson et al. [1997]). 

---