The New Use of an Old Source of Energy
The history of water-driven mechanisms goes back at least four thousand years. At first, the only ones were water wheels, until in ancient Greece, as early as the second century B.C., both the propeller turbine and the free-jet turbine (known as the Pelton turbine) came into use. Strictly speaking, patents should not have been granted for either of these in our times, since they were actually "prior art". These wooden predecessors of our modern sophisticated turbines do not differ from them in principle: they are all based on rotation, and the designers of the Greek propeller turbine were presumably aware of the transverse lift effect already.
Then as now, these rotating engines proved to need a head of water. Only a single traditional hydraulic engine manages without a head: the simple stream wheel. In minimum-sized installations with a volume flow under 1.5 m³/s and a speed of flow over 3 m/s, it can still do yeoman service today; but it is not commercially viable for generating electricity.
The stream wheel is a pure resistance wheel, and simply cannot provide electricity at a profitable price at a low speed of flow. Other possible ways of utilizing the kinetic energy of flow of the rivers without damming them or having a head of water, a large number of which can be found in patent office records, fail the financial test. Most of them would still be inferior even to the millennia-old stream wheel.
In most cases, the reason for this is that the lifting force of the current is not made use of. But without it they remain second-rate - birds flying and our modern reaction turbines make use of this force.
The bird flies forwards, but the blades of the turbine are meant to stay in place, and must therefore rotate about an axle, which necessitates concentration and location at a dam site for geometrically necessitated, economical reasons.
We could only abandon rotation in this case if it were possible to have the camber of the lifting surface reverse automatically through the force of the current when a certain limiting angle of excursion was reached, so that a wing suspended by an axle in the current would execute an oscillating motion. This seems very difficult, for in practice there is no question of using something elastic, it would have to be the kind of steelwork used in hydraulic engineering.
However, this is not impossible by any means. The strongest evidence that the thing one is searching for exists is the search itself. Such a new type of transverse lifting body would begin to move sideways at right angles to the current, reverse its direction, and return.
It exists. Let it be called Transverpello
Lutz Kroeber 2007