A customer called the EMPF Helpline with a question about using compact fuel cell technology as a battery replacement for hand held power tools.

A tremendous amount of research and development is currently investigating compact fuel cells to power electronic devices, and more efficient hand tools to reduce the need for the very high capacity cells that are now required. There are a number of offerings; power and capacity are rapidly increasing and viable fuel cell battery replacements that attach to a hand tool will be available. The use of fuel cells as an attached power source for hand held power tools promises to make the higher power and increased capacity available in a short timeframe.

A recent Navy ManTech study investigated the feasibility of expanding the use of battery hand held power tools and fuel cells to perform shipyard construction tasks. The study included an investigation into the technical readiness level, capability, and present market existence of small fuel cells as attachable battery replacements as well as compact fuel cells for use as an alternate power source with batteries as hybrid power for hand held tools. Further fuel cell capabilities were studied for powering battery charge stations off the commercial power grid or as replacements for small generators where their low exhaust and silent operation would be an advantage for use in confined spaces.

"Fuel Cell Manufacturing Challenges" and "Optimizing Fuel Cell Performance." were two articles that appeared in the August 2010 issue of Empfasis. They presented results of the data collection of fuel cell capabilities, fuel supplies, their advantages/disadvantages, fuel cell types, size, and power capabilities. Some information reported there is relevant for this topic as well.

One issue that must be answered in any application is an appropriate fuel source to supply the cell. In the one to 100 watt power offerings (which can power the targeted tool in lower power applications), methanol, propane, methane, butane, sodium borahydride, and ammonia borane are used as fuels in several types of technologies including direct methanol fuel cells (DMFC), reformed methanol fuel cells (RMFC), small solid oxide fuel cells (SOFC), and chemical hydride fuel cells. The investigation addresses fuel storage, safety, and handling issues that must be considered and resolved to have a cell form factor that is manageable and safely useable in the specific applications and atmospheres that the targeted tools are to be used. This is especially true due to emission issues of the fuel cell chemistries.

Of course, another set of serious issues are handling, size, and weight. To be used as an attachable power pack the supply must be low temperature, compact, and lightweight to limit the ergonomic, physical stress, and fatigue issues that are present for sustained use of hand held power tools.

Part of the tool power study reported on compact fuel cell availability via a survey performed by Concurrent Technologies Corporation (CTC) in Johnstown, PA. Some present offerings include devices for cell phone and laptop power and battery charging while others have a potential for use as tool power. For example, smaller capacity cells are presently being manufactured in specific form factors for cameras.

There are some promising fuel cells in the lower power region that could power some hand tools. One example from the CTC study is a device offered by PaxiTech in France. PaxiTech is marketing a planar fuel cell in the four to five watt power region that is adaptable as a flat package, expandable for additional voltage regions, and can be manufactured in many different form factors.

Another fuel cell is manufactured as an attachable accessory on a camera (Figure 2-1) by MTI Micro (Albany, NY). Based on direct methanol fuel cell technology, it features a five to 10 times increase in run time over a battery supply.

MTI Micro also offers a cord-free power pack that can replace current lithium ion and similar rechargeable battery systems in many hand-held electronic devices. Based on DMFC technology, the Mobion® fuel cell engine (Figure 2-2) has a power density of 84mW/cm2 while maintaining its fuel efficiency of 1800 Wh/kg (1.4Wh/cc).

There are many other small fuel cells currently available, the ones presented are just a few examples.

The study did not find any attachable, handle mount fuel cells available at this time with the sufficient power density and capacity to fuel a device used in metalworking. In this metalworking study, the offerings did not have the shift-long capacity for a sustained 13 watt output, even when accounting for a lower duty cycle. When requirements are needed in this higher power arena, a larger capacity cell is required and the focus shifts away from attached power to tethered power. But there is still a need for the attached power cells. The freedom that the battery powered hand tool offers is often required in many applications, especially in cramped spaces.

As R&D continues, fuel cells will improve in power as well as capacity and become more readily available.

For more information, contact the EMPF Helpline at 610.362.1320, via email at helpline@empf.org or visit the website at www.empf.org.