Whatever happened to OCGT or even CCGT?

[Nym]

Why after the APT-E was scrapped did no-one think to start using an Open or Combined Cycle Gas Turbine as motive power again.

The OCGTs aren't terribly efficent, but the CCGT could be ussed for traction, so long as it was running for a reasonably long distance, as it takes about 10mins to ramp up an CCGT plant, OCGT takes meirly 15 - 30 seconds, and thats damn close to diesel. Although you could have a Semi-Combined cycle for train heating and non-traction electrical supplies. So you could kick the ass off of Diesel in both KW/m^3 but maybe not on fuel power density, but all that would be coming out of the exhaust is water, come on, the goverment want more envimomentaly friendly, clouds are friendly, and if you run them here, no-one will notice the extra cloud anyway!

 

[djw1981]

IIRc transport of the gas was the issue - it had to be safe from explosion and fire in a collision. In order to reduce the space that the gas took up, it was proposed that it be pressurised, which altered the risk of fire in a collision unacceptably. There would also be lots of Co and CO2 pumped out, it would nly be cleaner in terms of no soot and particulate matter, but teh CO2 would still be anti Kyoto AFAIk.

 

[Nym]

What about Hydrogen OCT or Fuel Cells then?

 

[O L Leigh]

I'm still firmly of the belief that hydrogen fuel cell technology is a "blind alley" as far as green energy is concerned.

It's certainly being missold as being "zero emissions". The vehicles themselves may only be putting out water vapour, but the pollution has just been shifted to another part of the manufacturing and consumption chain. Likewise, because the only commercially viable means of producing hydrogen gas relies on natural gas, it won't break our reliance on the dwindling reserves of fossil fuels.

Sorry if this is off-topic.

O L Leigh

 

[Nym]

Exactly the same as things like electric cars, pepole don't relise that the electricity still comes from prime movers turned 31% of the time by coal and 37% of the time by Gas, with somting like Hydrogen Production, which can be made by Electrolysis, a very fast ramping production means which can drasticly level out electricity consumption so power stations wouldn't have to be ramped as quickly. So ultimatly it's still fossil fuels, but will mean that we can switch to more efficent generation as it wouldn't need to be ramped as quickly... Generaly the quicker you can turn it on or off, the less efficent it is. CCGT, Nuclear and Coal being the most efficent at 87%, 75% and 34% each, where as Diesel Generators and OCGT which is used for fast ramping in peaks is about 10 - 20% efficent, and doesn't have as longer lifespan, so if you can level the demand out with hydrogen plants, we can make more efficent use of the baseline plants which are more efficent.

Nym - Engineer in training

 

[O L Leigh]

Nym: OK, now you're talking engineering-speak which means that you've lost me totally.

However, commercial production of hydrogen gas cannot currently be done using electrolysis because the energy requirements are too high and the process too inefficient. Instead, it uses a process called "Steam Reforming" in which natural gas reacts with steam at very high temperatures (700-1100 Celsius) in the presence of a metallic catalyst. Unfortunately, the resulting brew comprises a large proportion of carbon monoxide that needs to be refined out to make the remaining hydrogen suitable for use in fuel cells, as carbon monoxide would rapidly "poison" a fuel cell.

At least a battery electric vehicle could be charged from a domestic wind turbine or solar generator, thereby removing fossil fuel from the equation altogether.

O L Leigh

 

[Nym]

Overall efficency and usage ratio of solar cells in the UK, Energy out / Maximum Potential Solar Energy Falling on the Cells

About 0.5%!
Wind power 30%, only effective when the wind is the right speed in the right direction

Anyways, Even the power density is getting better in batteries, it is still wayyyy toooo low!

 

[O L Leigh]

Maybe so. But if you're after a green private transport solution for journeys of a distance greater than you can manage on a bicycle, it is currently the best option.

I appreciate that the engineering and efficiency figures don't necessarily stack up, but it's a free ride and doesn't rely on energy generated by questionable means.

O L Leigh

 

[Nym]

Questionable means?

Shal I make my next sudgestion of a MAGNOX powered loco? AGR Powered? or make it PWR to be modern, would put a bit of strain on the cumbrian coast line through for re-fueling

 

[O L Leigh]

Perhaps I should have been a bit clearer and said "environmentally questionable".

From a green perspective, just plugging a battery electric vehicle into the mains means that there is a high chance that the energy being used has been generated either from fossil fuels or nuclear power. I would suspect that there aren't that many environmentalists that would be happy about that. Plugging into a wind turbine or solar generator means that they would be charging up on free renewable energy that has a zero carbon footprint, does not deplete finite energy resources and does not create highly dangerous by-products that are difficult to dispose of. In that sense, it could be said that the majority of the energy consumed in the UK is coming from "questionable" sources.

But then surely we're drifting even further off-topic...?

O L Leigh

 

[Nym]

OK, cerious question now, is a 200GW small reactor too powerful for a train?

 

[O L Leigh]

Answer: Very probably. A Cl317 at flat chat requires only 900V for the traction motors. I've no way of working out the wattage for these units, but 200GW sounds way too high.

I think the shielding and safety case in the event of a bump would preclude this anyway.

O L Leigh

 

[Nym]

might be able to babeyfie the reactor to the size of a 37, but I know I won't be the one to do it, Don't like nuclear, won't ever work on it. Seen what cock ups in nuclear medicine do. Anyways, I don't mind being near them, and it seems that nuclear is the only viable zero emmision option for the UK, unless we buy in from somwhere like Swizerland where they have enough hilly bits and run on mainly hydro, although somone came up with the idea once of lining the sides of lines with wind turbines...