There are many areas in the world where water and soil are available but where electric power is not available for irrigation. Solar powered pumps that use photovoltaic panels to provide electricity to drive pumps work well but are too expensive to produce sufficient water for irrigation use. Proposals have been made to use solar thermal energy, but these require relatively expensive collectors and require photovoltaic panels to supply electric power to operate auxiliary equipment. This proposal is aimed at developing and demonstrating a solar thermal irrigation pump that provides a large flow of water inexpensively. The pump will perform without any electric motors, electric valves, or other electric circuitry. The purpose of the Phase I project will be to construct a small irrigation plant that pumps water by energy from the sky. It will prove that a new revolutionary expander (motor that operates on high- pressure gas) and a new high efficiency pump will work together to pump large quantities of water. Solar energy will be collected and used to boil a low-boiling working fluid at high pressure. The vapor will be used to drive the new expander, which will drive the pump. ANTICIPATED RESULTS & POTENTIAL COMMERCIAL APPLICATIONS OF RESEARCH Computer simulations show that a large quantity of water can be pumped with solar thermal energy using a small, inexpensive solar collector. This research will demonstrate that. There is a large market for this kind of irrigation pump not only in the U.S. but all over the world. Sale of these units will help reduce the U.S. trade deficit. Water has become a more critical commodity in the world than energy. The use of solar energy to pump water would reduce the use of fossil fuel that is used in electric power plants, and in gasoline and diesel powered pumps.