Energy systems thinking a new design

"water vapour produced will carry considerable amounts of heat which can be recovered as saturated water vapour . "

 How  do you recover that heat, or any more than a small fraction of it ?

Generally anything cooler than super-heated steam is incapable of driving a mechanical system with any efficiency worth consideration.

As you rightly say, in a conventional system about 65-75 %of the energy released by combustion is not available as shaft horse power, it simply comes out as wasted heat we cannot use because the temperature difference relative to ambient is too low.

The old steam engine guys knew this and had triple expansion cylinders where the last one was essentially only 100C and venting into partial vacuum and a modern mutli-stage turbine does the same sort of trick but far more elegantly by having stacks of turbine blades at varying pitches and with various chamber volumes to extract energy at each stage of expansion and cooling, but you cannot break the 2nd law of thermodynamics.

I think there is commercial sterling engine unit recently been fitted to a power plant, unfortunately no pictures of whats inside the metal containeryet

The old steam guys certainly did know a lot , which is why they needed superheated steam for pistions and cylinders , the steam turbine changes things a little as its more to do with flow rate and how low you can get the pressure at the exhaust , Water vapour , superheated is carrying a lot of heat , which is why steam has continued in some processes however if we use the spent steam in a heat exchanger to pre heat BFW then less fuel is required ,to get to critical or super critcal steam pressures in the infeed to the steam turbine . 

A typical modern steam turbine will use around 50% of the steam energy which is usually condensed and fed back in to the boiler , although many large boilers to steam turbines use re heat sections . A typical solid fuel boiler will convert around 80% of the fuel energy to steam and around 50% of that steam energy gets converted into KW , hence why some of the old power stations are at 30% conversion of KJ to KW and even the most modern ones not using CHP cant yet reach 45% conversion . when you use CHP it gets to around 60% , however I believe my design will give an fuel to KW conversion of over 55% , as I can get much better heat recovery using a co fired (CH4 and solid fuel) oxy fuel system .

Just been doing some further calculations and think we would have enough fuel as a sort of bio solids/rdf mix at 10% moisture at around 18000kj/kg if we can get biosolids at 10% moisture in good kj fuel value . Looking at at a mixed fuel of around 18000kj/kg , and , probebably take around 15yrs to get a home grown biomass market beyond the current 2,500,000,000 kgs that isnt recycled . I was wondering if long leaf pine could be harvested every 15-20 yrs (to enable harvesting by direct uprooting ) might yield more biomass than 90yr planting of commercial conifer , also being as forest management is on the cards , there is the rakings from mature forests (around 2 every 90yrs ?). 

Just need the expansion and heat content figures and its looking good .

Even though ethanol is a good fuel to make , i dont think we can make enough to power a 500mw gas turbine and it would be difficult to gather it to a central user  so may be better to use ethanol locally . The hydrogen gas turbine is interesting , one maker is claiming 100% hydrogen can be used , my guess is that a purpose built gas turbine for hydrogen is the solution , but may not be 500mw .The hydrogen , oxygen fuel gas turbine would be a dream come true could do all sorts of power systems options with that and I think a good route to go for. I am not sure if the large battery is important now either , if we have hydrogen we have energy storagae for large fuel cells , and there are other solutions for peak plants for grids now , either pumped hydro or compressed air

The Hydrogen Oxygen combustion gas turbine would no doubt be a very useful thing , but i suspect 500mw is going to be difficult I think consumption wise this would be 260,000m3 of Hydrogen per hour plus 130,000m3 of O2 , 260,000m3 of hydrogen is 21,775kg per hr , so 1158mw of electrolysis ????

looking at Sequential oxygen combustion system , I think it can work well in 3 ways ,

1 when we have a surplus of CH4, it does act as gas balancer 

2 In the summer low of demands when the most spare wind energy is available 

3 we could certainly improve cement CO2 with it , depends how much of the 10,000,000,000 kg uk consumption you want to do , if this ammount of cement required then plant type and position will need configuring differently , in other words other than obvious sites dont draw anything till we can get figures , 

4 ethanol can be used for local specific power loads using reciprocating engine , should be making quite a bit if we really go for it  by 2030

It may be possible that any new cites have grids that reach so far and when times of surplus occures it goes to power station water electrolysis , not sure at moment but looks to me like we might have 2 sorts of grid , one that is one power station to feed an area , and one that has multiple power stations supplying it and multiple demands drawing from it .If national grid cannot deliver a high efficiency grid or grids might as well use gas engines at interconnectors , I think I can squeezein a 1000mw gas to steam turbine system at each site proebebly as 2 sequential 250mw lines , its peak electrical demands that are problem , but this bit of it looking good

I have no idea what that means.  What's the advantage of having two separate grids? 

Helios:

It may be possible that any new cites have grids that reach so far and when times of surplus occures it goes to power station water electrolysis , not sure at moment but looks to me like we might have 2 sorts of grid , one that is one power station to feed an area , and one that has multiple power stations supplying it and multiple demands drawing from it .