Audi making diesel from water, CO2, and electricity.

I am not sure about the practicality of this. Reading an article it sounds more like an R&D pipedream than reality, and if it turns to somewhat economically viable at ~$100/barrel with Keystone XL and Saudi OPEC powerplay it will never take off the ground.

 

Missed that. It takes filtration/separation, electrolysis, reaction to make blue-crude out of CO2 and water, and from this blue-crude it will need more energy/resources to get diesel.
Here can I find it in the text?

 

Highly unlikely...they are probably using the bogus numbers...dino diesel does not have to be synthesized from scratch, it already exists in nature.

 

Trollbait, The first step is hydrolysis in both FCV or this "bluecrude" process.

If to a FCV - fill up tank and 65% TTW efficiency, water tailpipe product
If to the rest of the path to e-diesel - reaction, further refining, 25% TTW efficiency and complex tailpipe emissions.

 

If I was a betting man, which I am not, I'd buy some H2 FCV stocks. The is so much institutional fear that FCV may be disruptive technology we are <not> hoping for.

 

Feeling confident ? Volunteer to be the next rat.

 

Color me skeptical about the energy lifecycle until I can read a scientific paper, but CO2 capture is pretty easy, e.g at centralized power plants. The difficult part is finding something to do with it.

Consider coal burn at a power plant:
First pass ~ 35% thermo efficiency, ~ one Kg emitted CO2 per kWh
--
Then the collected CO2 + 1.0 kWh electricity -> 0.7 kWh diesel

So we can view this as a way to convert coal to diesel that costs 30% of coal's energy.

 

Coal to fuel conversion was already made in WW2 by the Germans.

About that second pass, if 1 kWh electricity comes from coal, then e-diesel will only be 25% "coal efficient". And another problem of capturing CO2 at coal plant is that you capture also a lot of other emissions.

 

Audi is not planning to make gasoline, they are doing methanol for cng cars, ethanol to blend in gasoline cars, and diesel. Once they have the methane they can convert it to diesel using the same technology shell is using and sansol is planning.

I'm sure it was a typo and yes the start is electrolysis to produce H2.

To provide hydrogen for fcv first you need to build the fcv, which are much more expensive today than similar diesel vehicles.(not sure what audi costs but a bmw 328d which seems much nicer than a mirai costs over $10,000 less than a mirai after tax credits in the US. say the bmw (37 mpg combined epa( needs 65% more diesel than the mirai (? miles/kg) needs 10,000 psi h2.

Both are using renewables right? How much less will that renewable diesel cost than the compressed hydrogen? Probably alot. Sansol thought they could make diesel for about $4 gallon from natural gas. Lets say that is $4 more than the hydrogen cost, or $4*1.65 =%6.60 more than renewable hydrogen processed at off peak times.

Now look at what you have to build to fuel the mirai with hydrogen. Each station costs $2M+ each. If you are doing renewable hydrogen centrally, you need to liquify it, and truck it which costs more than that extra diesel cost right there. So you have to build electrolysis at each station, have a tank big enough to store it, compress it, etc. NREL says if you only have 50,000 cars that will probably cost $12/kg. Get 15% of the cars on hydrogen, and you may get it down to $2/kg+cost of hydrogen if you overbuild wind as they are planning in germany. Today its much cheaper to build the wind turbines and convert to diesel, than to build the hydrogen fueling infrastructure. You can also use this wind in plug-ins/

I would bet that the renwable diesel + diesel car infrastructure, costs less per mile unless some big breakthrouhs are found with fcv and hydrogen. Germany, the US, Japan and others are funding research, but it is a long shot.

 

I see PHEV and BEV as the only near future solution and a simple PHEV like PiP should not be that expensive in near future.

As I said earlier 5 l/100 km of e-diesel is equilinat to more than 70 kWh/100 km and a car like 328d will never reach it
FCEV with 1 kg/100 km uses from 50 to 79 kWh if it's from water electrolysis

 

GasperG, I agree completely on the first point.

On the second, the fuel cell lobby argument on renewable electricity is it will be so cheap that it doesn't matter how much less efficient it is. Let's take an optimistic 50 kwh to make 1kg of hydrogen at a station. In a diesel you might get 60 km (37 miles) on that energy, in a fcv 100 km (62 miles), in an average (104 mpge) plug-in you go 247 km (154 miles). Now in a big central plant you can just turn on the electrolyser when power has excess renewables, and locate this near the wind farms. A stand alone station is not likely to do this unless it has a very expensive tank that lasts a week. I would posit that the hydrogen fueling infrastructure would cost a lot more than the extra wind farms. Charging a plug-in at night would take a lot less net renewables than either other option. Der Spiegel noted that even in 2050 there is unlikely be enough cheap renewables in germany to run a large volume of hydrogen cars, and small volumes make the fueling infrastructure/kg or km very expensive.

Note on this cheap intermittent renewable hydrogen we could make methanol or ethanol more cheaply per unit of energy and blend it with gasoline in a flex fuel hybrid or phev. That would probably be the most cost effective way to use this renewable hydrogen for transportation.