A method of making espresso and a portable espresso machine incorporating
that method that is compact, lightweight, requires low power, and is
readily transportable. The quantity of water required to make espresso is
heated to the brewing temperature in a boiler equipped with a piston. The
piston is driven by an electric motor. During the brewing cycle, the hot
water is pushed by the piston through the compacted coffee contained in
the portafilter. The rate of piston movement is chosen such that the
coffee in the portafilter is infused by the hot water at the high
pressure necessary for making espresso, typically about 100 psi or
higher, and also such that the contact between the coffee and water is of
a duration suitable for making espresso, typically about 15-25 seconds.
The components are thermally insulated and strategically placed to
minimize the size of the machine and allow for portability.