SOLAR-JET aims to ascertain the potential for producing kerosene from concentrated sunlight, CO2 captured from air, and water.

http://www.solar-jet.aero/

Sounds like an interesting EU funded project !?

A litre of diesel in the UK is about € 0.714 before taxes according to the EU Energy Portal.
€ 0.596 in Sweden.

So that says we need a €0.286/litre carbon tax, doesn't? That'd be about €0.42/kg of carbon or €1.54/kg of CO₂. Matches well with suggestions I've seen elsewhere of US $100 to $200/tonne of CO₂ which had seemed to me to be very low.

Posted By: HalcyonRichardAll the fuel produced from renewables is carbon neutral.

Are they not taking a clean fuel and turning it into a dirty (but granted easier to use) fuel?

Having quickly looked at their website I can't see any mention of the source of the carbon dioxide that is used as the basis of the fuel, but presumably when the fuel is burnt it is released into the atmosphere along with particulates and various other by products of combustion?

No less damaging to the environment than fossil fuels save for the actual drilling process? Just dressed up as being carbon neutral to make it seem so.

Hi Chris,
The carbon dioxide is from the atmosphere. This chemically reacts with water under the right conditions/temperatures. The products are methane and oxygen. i.e. 2 molecules of carbon dioxide plus 2 molecules of water plus energy become 2 molecules of methane plus 3 molecules of oxygen. Chemical equation is -

2 X CO2 + 2 X H2O TO 2 X CH4 + 3 X O2

When the fuel is burnt the CO2 is returned to the atmosphere. So it is carbon neutral. The fuel is very pure and has far less contaminents than natural gas. Further reactions produce higher chain carbon based fuels. If diesel is produced then it would probably have the same problem as conventional diesel as regards particulates.

Richard

PS this system can also be used to generate aviation fuel. This replaces fossil fuel. There is currently no other way to do this apart from biomass options.

Posted By: fostertomcompared to turning same ingredients into electricity made 'portable' via batteries for transport?

When it comes to aviation or the road freight industry battery power doesn't really cut it does it?

This appears to give society the option of continuing down the IC path without the reliance on fossil fuels.

Not truly green and still polluting but appears to be a little better than the current options, no?

Posted By: HalcyonRichardWith the big renewables being highly variable something needs to iron out the peaks and troughs

Are they really highly variable. They vary, but it is very predicable, usually a few days in advance. That is just a capacity issue really. Install enough, in enough places and it will supply the demand.

As I have hopefully shown on the grid stability thread, a small amount of storage in millions of homes is all that is needed. Even allowing for losses.
If you want to store and release quickly, you need a system that can do this, pumping air and steam though a high voltage, collecting the condensate, getting rid of the by products safely, storing the condensate, shipping it to point of use and then burning it, is probably not a brilliant solution. Though it will have some uses somewhere.

Posted By: HalcyonRichardBut if you get cloudy and windless month in the winter you may need to install many times the average demand

Yes, and that is the problem.

When I compare renewable technologies, I use PV as the benchmark. Basically because it converts our most abundant energy source to our most useful energy supply, it is also reliable being non mechanical. it just sits there doing its thing.
There was talk of these Redox batteries improving (not that I took much notice), but that may be a better use of storing energy. Though transport, especially flight, benefits from throwing the converted fuel out the back, it reduces mass, better than throwing cargo or passengers out the back.

Posted By: fostertomthat's why it's so scary that everyone's ignoring it.

It is generally ignored because it is not a good measure without putting bounds on it.
Take any bounds off, and it becomes a nonsense unit, but we have done this before.

Hi Tom,
I think I have this right - but would like to see what you think. The diagram is from WIKI :-

http://en.wikipedia.org/wiki/Energy_returned_on_energy_invested

Wind turbine EROEI Europe/USA is 18. The energy to gas (methane) is say 70% efficient. Gas to energy is 60 % efficient. Pro rata the cost of 1 kWh of wind energy to 1 kWh of "gas" Then the EROEI is about 7.5. Ignoring the wind energy. So hope this logic stands up.

Wind 1 kWh in 18 kWh out. Energy to gas 18 kWh in PLUS 0.6666 kWh "running/operating" @ conversion efficiency of 70% and back of 60%. Then energ out = 18 x 0.7 x 0.6 = 7.56 kWh

Energy input = 1 + .66666 EROEI for wind to gas to electicity is 7.56/1.6666 = 4.53

So best to use wind as it is generated. But it is not that bad to use it to smooth out differences in supply and demand. Surprised at solar PV EROEI of 6.8.

Richard

I don't see anything about 'bounds' by name, unless you mean it starts off saying
"The natural or original sources of energy are not usually included in the calculation of energy invested, only the human-applied sources"
I agree with that, and said it in my post above.

Do you mean
"How deep should the probing in the supply chain of the tools being used to generate energy go? For example, if steel is being used to drill for oil or construct a nuclear power plant, should the energy input of the steel be taken into account, should the energy input into building the factory being used to construct the steel be taken into account and amortized? Should the energy input of the roads which are used to ferry the goods be taken into account? What about the energy used to cook the steelworker's breakfasts? These are complex questions evading simple answers. A full accounting would require considerations of opportunity costs and comparing total energy expenditures in the presence and absence of this economic activity."

I say Yes to all that, and probably more, to the max anyway. If you're applying 'bounds' by saying No to that, then I'd call that incomplete or self-deceiving accounting; for example we see plenty of

"However, when comparing two energy sources a standard practice for the supply chain energy input can be adopted. For example, consider the steel, but don't consider the energy invested in factories deeper than the first level in the supply chain."

AFAIC the Wiki article magificently supports what I wrote above.

Posted By: fostertom
I say Yes to all that, and probably more, to the max anyway.

There has to be a cut-off point somewhere though, for purely practical reasons. We don't have infinite knowledge available about every conceivable input, and at a certain point they become trivial.

I have just had a look around the www.sunfire.de /Bilfinger website and I get the impression that they are looking for investors that don't understand technology.
On the technical pay they claim that they can produce 250 kWh from 600 lt, that is under 1/2 kWh per litre, or a twentieth of normal kerosene. Not sure if this is a translation problem or what, but there seems to be little real evidence that this system works at a large scale.

Hi Steamy,
They have been working with the Frauenhof Institute. I have also done work with Frauenhof. They carry out R&D for industry and are part subsidised by the German government. Sunfire have working systems. I would think it is a typo/translation error.

Richard

Hi Steamy,
Is this the stuff :-

Power output: 250 kW up to several MW, equivalent to 600 Liters/d up to several thousand Liters/d

Fooled me for a bit as well. It states power then liters/day. So I would think that 250 kW for a day for 600 litres of fuel. i.e. 250 x 24 kWh/ 600 litres This gives 10 kWh/litre.

Richard