**7. Economic overview analysis and potentialities**

All possible application and the alternatives of the proposed device must be investigated. It appears obvious that a UMGT will be utilized in the two main area, already covered by the large scale machines:


The primary application filed will be the first one; the higher energy density respect to a chemical battery with an overall efficiency of the 5-10% is sufficient to render a UMGT more attractive on the market. Substantially fuel tank is the bigger component, for which reason, in the developments of such machine, the researchers have to obtain low consumption than to high power output, thanks to the possibility to satisfy the power requirements through "modular clusters". Besides the possibility to feed every type of portable device, a such generator could go satisfy the power requirements of aircraft onboard systems, in terms of redundancy and higher operational temperatures, in comparison to the conventional battery packages. The competition with the large scale power plant is not possible, because is not imaginable of achieve efficiency of the order of 50-60%. The situation would be various in the moment in which will be possible to obtain, for example with regeneration, efficiencies

mechanical tests on the material. The adoption of this technique wants substantially to reduce the excessive long times of bonds production of the CVD or the DRIE on SiC wafer, caused by the speed of material deposition and recording, and to the lack of accuracy of the

All possible application and the alternatives of the proposed device must be investigated. It appears obvious that a UMGT will be utilized in the two main area, already covered by the

The primary application filed will be the first one; the higher energy density respect to a chemical battery with an overall efficiency of the 5-10% is sufficient to render a UMGT more attractive on the market. Substantially fuel tank is the bigger component, for which reason, in the developments of such machine, the researchers have to obtain low consumption than to high power output, thanks to the possibility to satisfy the power requirements through "modular clusters". Besides the possibility to feed every type of portable device, a such generator could go satisfy the power requirements of aircraft onboard systems, in terms of redundancy and higher operational temperatures, in comparison to the conventional battery packages. The competition with the large scale power plant is not possible, because is not imaginable of achieve efficiency of the order of 50-60%. The situation would be various in the moment in which will be possible to obtain, for example with regeneration, efficiencies

EDM (Electro Discharge Machining).

Fig. 28. Micro Reaction Sintering phases

large scale machines:

• the power generation • the vehicle propulsion.

**7. Economic overview analysis and potentialities** 

about 20-30%. So the lower performances could be compensated with the advantage of the redundancy, the lowest noisiness and the UMGTs compactness. Such levels are still the much far being reached. On the other hand, in the emergency applications, where the efficiency is not a limiting requirement regarding the compactness, succeeding to contain the costs, a UMGT would not have rivals. Three requirement that render this device a lot attractive are therefore, compactness, redundancy and lower noisiness thanks to the speed frequencies of hundred of kHz (beyond the audibility threshold) and to the length small scale (the exit flow is quickly stirred with the surrounding atmosphere). In propulsion system this device is considered as one of the more attractive relatively to little reconnaissance planes (100-1000 g of takeoff weight), thanks to the high thrust/weight ratio, which scale with the inverse of the length. The ICE motors currently under construction for these applications, are ten times greater, much noisy and with greater fuel consumptions. The possibility to use UMGT cluster, for the propulsion of great aircrafts is remote, as it seems improbable to succeed to obtain lower consumption to performance parity, without to count eventual difficulties of assembling process, due to the elevated number of necessary devices (at least 105). The determining factor in the diffusion of a UMGT system resides , however, in the production cost. In fact, the production of this devices presents high manufacturing cost, tied to the complex technologies to adopt, amortizable with the production in large series scale. According to an esteem of the MIT (a CMOS silicon wafer of 200 of millimetre of diameter can cost \$ 600-1000), if produced in large scale, a wafer of MEMS generators could produce several kW to the cost of several thousands of dollars for the fabrication. The result is a specific cost of 0,5-5 \$/W. Other considerations have to be done for civil application and for higher power rate (within the UMGT power rate). Here below it is discussed a practical case study.
