exhaust/engine cooler heat recuperator

[Creativity]

true,
1)but turbo(you only mean an exhaust turbine attached,without compressor?) introduces a pressure restriction into exhaust and creates a back pressure.Back pressure is only a good thing on low rpm's when the valve timing has a big overlap in intake and exhaust(race machines,motorbikes => see yamaha EXUP valve).In all other cases back pressure is working against the engine(engine in exhaust phase has to push against this back pressure -loosing energy)
2)turbine spins in excess of 100.000 rpm's and the speed of it is varying by as much as 60%,there is simply no gear to gear it down to max 15.000 rpm needed by a standard alternator.So high speed alternator would be required capable of fast changing in rotation speed.

maybe you could go around second problem by using turbocharger to compress the air and then to run it through the other turbine with lower rpm's to run the alternator.

[Creativity]

i did some calculations yesterday,it seems that water steam is kind of tricky .It needs a lot of energy to turn water into steam (like 2,5 kW per 1 g per s) it is because of the high vaporisation heat.I will bring u a fast overview(with rough numbers):

turbine i bought will need 8cfm(250 l/min) of uncompressed air to produce 0,8 kW.But first this amount of air should be compressed to 6,5 bar (90psi).So roughly speaking i need 4,5 l of uncompressed air per s.1 g of water produce 1,6 liter of uncompressed steam,so i need let say 3g of water to be evaporated per s.
It is then 7,5 kW energy absorbed from exhaust.Alternator efficiency 60%.
7,5 kW vs 0,8 *0,6=0,48 kW produced. Quite low conversion ratio.By getting turbine to run on 30 bar(high pressure!) situation would be more beneficial.

Still! I looked around for other working gas/liquid.Best i found is methanol (unfortunately flammable).It has hear of vapourisation of an order less than water.
it takes 0,11kW to evaporate 1g of it.1 g of methanol produces 1 l of uncompressed gas=>4,5 g evaporated per s=> 0,5 kW absorbed
0,5kW vs 0,48 kW produced is a big step forward comparing to water.

but i still look to find some nonflammable gas liquid with vaporisation temp higher that 40*C (so higher than ambient air temp so i can condensate it)and vaporisation heat lower than that of water.

anyhow i see a methanol as a good working fluid for even inefficient solar heat panels (temp of vapourisation under normal pressure of 65 *C! ) to generate electricity.In the full sun u can easily get 120*C in an empty sun panel wit a lot of steam.Prefferably put is somewhere in the garden and not on the roof (still a bit concerned about the fire in case of leakege).Fortuanetely it would require a small panel and only small amount of methanol to run the thing,so fire would not be severe .Maybe i should build first a sun panel as a proof of concept.Cold side with condenser would be in the shadow.

(i just started with steam systems so i may make some mistakes here and there)

[Creativity]

in fact...to tell the truth i was a bit shocked yesterday when i did exact calculations,because even with all the loses heat to electric conversion was above 90%(for methanol).too good to be so easy
I guess i still don't get some concept around 

[Creativity]

OK i was looking around some more and found a mistake.I bring here my calculation so maybe someone could verify.
It goes about the solar heat mirror collecting the high temperature (at least 240 deg C) sun beam to evaporate the methanol.240*C is the critical point for methanol (above it no methanol can exist in a liquid form no matter how big is the pressure).Boiling point for methanol under normal pressure is 65degC.
Super heated methanol vapour ,under pressure of 6,3 bar goes through the air turbine of the grinder.Grinder exhaust 7 liters of air per second to produce 0,4 kW of mechanical power.turbine operates best at 5000 rpm (half of its max no-load speed) and runs alternator of efficiency = 60% producing around 0,24 kW electricity.(efficiency from wikipedia,grinder ratings from producent technical specifications)

now tricky part:

methanol has density of 792kg/m3 and 1,332 kg/m3 when evaporated under normal pressure so i calculated that it expands 600 times in volume.
Next i took the gas law (http://en.wikipedia.org/wiki/Ideal_Gas_Law) to calculate how much would volume increase if i heated this vapour to 250*C (isobaric).
T1=65*C,T2=250*C under normal pressure and V1=600  .V2=600*250/65= 2300.
I concluded that 1 l of methanol when evaporated at the temp of 250*C would occupy 2300 l of volume.

to get 7l/s i will need 3ml or 2,41 g of methanol evaporated per second at the temp 250*C.

methanol heat energy 2,55J/gK. to heat methanol from 60*C to 240*C(above it is just a gas and heat energy is way smaller ,so i  negated the 10*C of heating it),temp difference of 180*C:
180*2,55*2,41=1,1 kW power absorbed

methanol evaporation energy 0.11 kJ/g.To evaporate 2,41 g takes 0,265 kW

So in total 1,365 kW absorbed to create super heated vapour from liquid methanol.

Air turbine will turn it into 0,4 kW of mechanical power and alternator with efficiency of 60% will make 0,24 kW electricity.

I come to maximal efficiency of 17% not counting the mirror Sun concentrator efficiency and heat losses.

with sun rate of 1kW per 1m2 the system would put out 170W of electricity.

I think it is a great deal considering that we could swap alternator for a solid magnet generator (around 80% efficiency),the thermal loses will be small as only a small amount of installation would need insulation.
It is cheap too!
pneumatic grinder cost me 20E second hand,now i would need some used car airco cooler (50E+) if i want to run it in a closed cycle,some copper pipes (1meter of so),solar concentrator can be made out of a satelite dish covered with silver(i am looking for some info how to do it).
I think the whole system would cost like 150E max with second hand parts,producing 240W + heat from condensation of methanol in the airco cooler.

any suggestion folks?

[Creativity]

Besst for mirror would be an aluminium satelite dish.aluminium can be chemically or electrochemically put into a high reflective sufrace,with low cost
i made some extra calculations to see what would be the best max temperature to operate on.The lowerst temperature is around 150degC,then the vapour pressure rises to 6.5 bar and grinder can be operated on rated power.At 250degC pressure rises to 34 bar and i think i can't handle that much so easily ;)Also the temperature will rise only to the level of the pressure selected.If my setup will operate on 6.5 bar temperature will stay 150C.The higher the pressure the higher the efficiency on the turbine.Lower temperature means lower heat loses.
Good news is that some companies tried to use methanol already as a replacement for freons in home solar heaters!It is thus enough safe to use i guess.second thing is that it will use max 0.5 liter of methanol to run this baby