Geothermal handbook: PlanninG and Financing power Generation t e c h n I c a L r e p o r t 2 / 2

Other Technologies
dry steam | 
Dry steam technology can be used when a geothermal reservoir produces pure hot steam, 
as in some areas of the United States (especially California), Italy, Indonesia, and to a lesser extent 
Japan and New Zealand. The technology is similar to flash or conventional steam, except a separator 
to separate fluids and steam is not necessary; units are large and operate with high efficiency.
Back pressure units
| Back pressure units are steam turbines that exhaust the incoming steam, whether 
dry or wet, directly to the atmosphere. This makes them compact, simple to install and run and the 
cheapest choice available. However, they are normally used for a limited amount of time (e.g., as test 
units or wellhead generators) until a better solution can be found, since the absence of reinjection 
hampers the long term use of geothermal power generation. Back pressure units have a lower 
efficiency relative to the other technologies mentioned above, which means they generate significantly 
less power from the same amount of steam. They can, depending on the chemical composition of the 
fluids and steam, be hazardous to the environment.