Direct-methanol fuel cell
A subcategory of Proton-exchange fuel cells is the DMFC, or direct-methanol fuel cell; here, the methanol is not reformed, but fed directly to the fuel cell. One does not need complicated catalytic reforming, and storage of methanol is much easier than that of hydrogen because it does not need to be done at high pressures. The energy density of methanol (the amount of hydrogen in a given volume) is orders of magnitude greater than even highly compressed hydrogen. However, efficiency is low, due to the high permeation of methanol through the membrane, and the dynamic behaviour is sluggish. Methanol is also extremely poisonous.
As a result of these strengths and problems, DMFCs are limited in the power they can produce, but can still store a lot of energy in a small space. This means they can produce a small amount of power over a long period of time which makes them well suited to power consumer electronics such as cell phones and laptops but rules them out of automotive applications.
As of 2005, the record for the smallest fuel cell is held by Toshiba, at 22 x 56 x 4.5 millimeters. This device outputs 100 milliwatts at 10 hours per milliliter of fuel, and takes advantage of new technology allowing the use of undiluted (99.5%) methanol.
Reference: Toshiba press release