Audi Creates "Fuel of the Future" Using Just Carbon Dioxide and Water

EwanPalmer writes: German car manufacturer Audi says it has created the "fuel of the future" made solely from water, carbon dioxide and renewable sources. The synthetic "e-diesel" was made following a commissioning phase of just four months at a plant in Dresden, Germany. Germany's federal minister of education and research, Dr Johanna Wanka, said she has already used the fuel in her Audi A8, and the company hopes to produce at least 160 liters of the crystal clear fuel every day in the coming months. "This synthetic diesel, made using CO2, is a huge success for our sustainability research," Wanka said. "If we can make widespread use of CO2 as a raw material, we will make a crucial contribution to climate protection and the efficient use of resources, and put the fundamentals of the 'green economy' in place."

Comments

With the best will in the world...

[Viol8]

...renewables are going to have their work cut out for themselves just supplying a majority percentage of the power for national electricty grids. I'm not sure where they think the extra renewable power to do this will come from.

Now if they plugged the process into a nuclear power plant OTOH...

Of course the big question is how efficient is the process? Is it more efficient than just using the electricity to charge up batteries in an electric car for example?

Re:With the best will in the world...

[goodmanj]

You're right that we don't have enough renewable energy yet to make this a useful technology. But hopefully that day is coming.

Re synthetic diesel, it's like I've always said: screw the "hydrogen economy", hydrogen is cryogenic, low-density, and difficult to work with. You'd be better off joining those hydrogens to some nice stable carbon atoms to create a storable, pumpable, relatively safe room-temperature liquid fuel.

Is it more efficient than just using the electricity to charge up batteries in an electric car for example?

Maybe, maybe not, but I guarantee you it has a higher energy density than batteries, which is super important for vehicle applications.

Re:With the best will in the world...

[gtbritishskull]

Normally, diesel fuel is burned thus...

Diesel Fuel + Oxygen -> CO2 + H2O + Energy

So, I would assume the opposite would be...

CO2 + H2O + Energy -> Diesel Fuel + Oxygen

The reason why diesel engines have problems with NOx emissions is because the high temperatures and pressures in diesel fuel cause the nitrogen in the air to react with oxygen. Nitrogen is not normally a component in diesel fuel.

Along the same lines, cars burning this fuel would probably still have NOx emissions.

Re:With the best will in the world...

[pushing-robot]

No, my car has an air filter.

Re:With the best will in the world...

[nonsequitor]

Regardless of the efficiency of the process, overgeneration of renewable power is still a huge problem. Germany actually pays its neighbors to take it when the wind is blowing and the sun is shining as the price of electricity between utility companies goes negative.

There are a few things we currently do with excess power, the ideal option is to store it until we need it, such as with compressed air in salt caverns.

In many cases, they dump it as heat into rivers as the storage infrastructure simply doesn't exist. This new option seems to be a great way to sequester carbon and deal with excess power generated through renewables. It also reduces our dependency on oil without having to sell new vehicles to utilize it, which is a very good thing.

Re:With the best will in the world...

[LWATCDR]

"Is it more efficient than just using the electricity to charge up batteries in an electric car for example"
Think of ships, planes, and remote locations where you must transport fuel like Alaska.

"You're right that we don't have enough renewable energy yet to make this a useful technology. But hopefully that day is coming."
No it will not.
Nuclear is the key to low carbon power. Wind and Solar will help but they do not work well as baseload. Thorium based nuclear and possibly Fusion aka Lockheeds High Beta reactor is what is needed.

Re:With the best will in the world...

[tomhath]

Fossil fuel is solar energy.

Re:With the best will in the world...

[Rei]

"Maybe, maybe not"? Please, you know that the answer is "not even remotely close". Even when you start with petroleum as your feedstock and only waste 10-15% of the energy it contains in refining and distribution, you've still got the car only turning 20% of the energy therein into useful kinetic energy (25% in the case of diesels), versus an average of about 85% of the electricty into kinetic energy (minus about 8% transmission losses), plus automatically gaining hybrid-style regen. Even if the process was 100% efficient - which it won't be anywhere even close to that - just the difference in propulsion technolgies would put the EV at 4 times the efficiency. Based on related processes, I'd wager that this tech is probably along the order of 30% efficient, so you're looking at about 13 times more range per kWh on an EV than a ICE car fuelled by this fuel. Which means 1/13th as many square kilometers of wind turbines, 1/13th as many solar panel factories, 1/13th as many dammed rivers, etc. Yes, it really matters.

But come on, don't play dumb and pretend that you actually think that the efficiency of taking electricity, extracting gases from the air, converting them into a mixture of complex hydrocarbons, then burning them in an ICE and facing Carnot losses, is somehow "maybe, maybe not" more efficient than using the electricity directly.

it has a higher energy density than batteries, which is super important for vehicle applications.

It really, really isn't. Almost everyone on the planet would be driving an EV at today's energy densities if one factor was significantly improved, but that factor isn't energy density. It's cost per kilowatt hour.

A 250Wh/mi EV that can go 400 miles (8 hours driving without a stop at an average speed of 60mph) needs 100kWh. At a reasonably good but not spectacular 200Wh/kg, that's 500kg. Due to electric drivetrains' superior power density, switching a low power gasoline drivetrain to an equivalent electric one saves about 100kg. Switching a high power gasoline drivetrain to electric can save a couple hundred kilograms. So you're increasing the weight of a car by a few hundred kilograms. You really think your average consumer would give a rat's arse if their car is a couple hundred kilometers heavier if it lets them drive on fuel that costs a third as much?

Of course, these are only a couple of the issues (I'll ignore environmental ones for now because I know a lot of people here don't give a rat's arse about them). Added weight hurts handling on cornering. But EVs make better power to weight ratios easier, and especially improve performance on low end torque. They also give designers a lot more flexibility on placement of components, which can translates into things like more spacious interiors for a given vehicle footprint, and almost always means a lower CG. One has to charge, but one never has to go to a gas station, and most people would find plugging in in their garage much more convenient than a special trip to a gas station and standing outside in whatever weather. This leaves open the question of charge times, of course. But if you can drive hundreds of miles on a single charge and charge up on a fast charger during lunch and then take off again, it's pretty irrelevant. Gasoline cars need big tanks to minimize the inconvenience of having to stop for gasoline regularly in your daily life. Using fast chargers of course means having a fast charger infrastructure, but that's an eminently addressable chicken and egg problem. Modern li-ion batteries deal quite well with fast charges.

The short of it is, if today's batteries were cheap enough - no better density or anything else - electric cars would very quickly take over the market place. Other improvements in technology will improve the sales proposition, but they're not essential.

Re:With the best will in the world...

[Thelasko]

The reason why diesel engines have problems with NOx emissions is because the high temperatures and pressures in diesel fuel cause the nitrogen in the air to react with oxygen.

The high temperatures and pressures in the combustion chamber cause the nitrogen and oxygen in the air to react with each other to form NOx.

Source: I'm a diesel emissions engineer.

Re:With the best will in the world...

[Rei]

Saying "Now design a battery that can pull a 440,000 pounds or 200,000 kilograms triple trailer configuration across hundreds of miles of highway. " is silly, that's like saying "Now design a gas tank that can pull a 440,000 pounds or 200,000 kilograms triple trailer configuration across hundreds of miles of highway. " Batteries don't haul loads, electric motors do. And electric motors have far more power per unit mass and per unit volume than gasoline. Here's a comparison between a gasoline car engine and an equivalent power electric motor.

The heaviest haul vehicles *do* use electric drive. The vast majority of trains today, for example, are electric drive, and increasingly large haul trucks are switching to electric drive. The electric drive however is generally driven by either diesel generators or direct grid power to save the cost of having to buy batteries. Due to the battery cost, the largest ones out there re things like BYD's 60 foot / 120 passenger jointed bus and several models of 15-30 tonne haul trucks. The economics just aren't there for road trains like you're talking about at this point. It's not a tech issue, it's a battery cost issue.

Supplying the power is easy. Just thinking about it from a practical standpoint. These are batteries that can fast charge in half an hour or so. Discharging is generally easier on batteries than charging. But let's just say half an hour discharge. Li-ions now get up to a couple kilowatts per kilogram, but are only a couple hundred Wh/kg at best in terms of energy density. A road train may require something like 1000hp. That's 750kW electric. Actually less because you get a smoother torque curve, but let's ignore that. That's about 375kg of good li-ion batteries to be able to provide the needed power. Let's double that for poorer batteries, and add a bunch more for inefficiencies... let's go full overkill and say we need 1000kg of batteries to provide the needed power. 1000kg of batteries would hold about 200kWh of electricity. That's only 80 miles of range. Which is way less than you'd practically need for a road train.

That is to say, even with the most pessimistic look at it, even a pathetically under-ranged road train would have way more power than needed to run its engine. The more batteries you add, the more power becomes available. Power density is essentially a non-issue when dealing with li-ions.

Also look at aviation, liquid fuel is going to be the practical choice far into the future.

Aviation is the highest-hanging fruit, but it's still a fruit that is within reach, and the small-scale electric prop plane market has gone from almost nonexistent to rapidly growing in the past 5 years or so. And there's lots of transitional techs, such as driving the compressor with electricity, which allows you to get rid of the turbine and thus increasing engine power and efficiency while reducing part count and maintenance.

The motors and batteries also require rare earths with are in short supply and require massive mining operations to supply.

False. First off, only permanent magnet motors require rare earths. Most modern EVs, like Tesla's offerings, don't use permanent magnets. Secondly, lithium-ion batteries do not use rare earths; I don't know where you got this idea. Lastly, rare earths aren't actually rare. China dumped the market, pushing other producers out of business, and then suddenly started holding back production for domestic uses, creating a temporary glut, but it's already started resolving itself.

An it's just not a matter in installing fast chargers, widespread adoption would require an overhaul in the electric grid.

This is once again false but I've already lost enough interest in this conversation to have to dig up research papers for you, so I'm just going to tell you "Google It". There've been many studies

Re:With the best will in the world...

[Solandri]

Even when you start with petroleum as your feedstock and only waste 10-15% of the energy it contains in refining and distribution, you've still got the car only turning 20% of the energy therein into useful kinetic energy (25% in the case of diesels), versus an average of about 85% of the electricty into kinetic energy (minus about 8% transmission losses), plus automatically gaining hybrid-style regen. Even if the process was 100% efficient - which it won't be anywhere even close to that - just the difference in propulsion technolgies would put the EV at 4 times the efficiency.

Slow down there. You're comparing the complete-cycle efficiency for petroleum to just the end-stage efficiency for electric. That electricity needs to be made somehow. Toss in 40% efficiency for coal plants (we'll leave out pumping/mining and fuel transport costs for now, assuming they're similar for oil and coal), battery charging efficiency of about 75% (discharge efficiency is unspecified, but since the EPA mileage estimates are based on battery capacity it's safe to ignore it), and the 85% motor efficiency you've specified, and suddenly your EV is .4*.75*.85 = 25.5% efficient. Same as a diesel.

This is the big thing a lot of EV proponents miss. Their EV is cheaper to operate not because the EV is more energy-efficient, but because coal is so much cheaper than gasoline. Coal costs about $50 per ton. A ton of coal has approximately 24 GJ of energy. That's about 0.21 cents/MJ. Gasoline costs about $3/gallon, and has about 120 MJ/gallon, or 2.5 cents/MJ. For the same amount of energy, coal is an order of magnitude cheaper than gasoline, which gives the EV a huge advantage in terms of operating costs. This is not a bad thing - being able to transfer a cheaper but traditionally static energy source into use in a mobile application is an economic win. But don't confuse it for better efficiency.

Yes you could argue that we can make electricity from renewables. But the vast majority of the cost of renewables is in the initial production of the turbine or PV panels. Operating costs are nearly nil (limited to maintenance). So for a fair comparison you then need to incorporate production and transport costs. At which point renewables lose because on a per Joule delivered basis, even with coal plants being only 40% efficient, coal is still cheaper than wind and solar power. (Wind is only about twice the costs of coal, so cheaper than gasoline, but I suspect solar would be about the same cost as gasoline.)

Re:With the best will in the world...

[tburkhol]

There will be another Chernobyl/Fukushima scale nuclear disaster.

Fine by me. Industrial accidents are part of the price we pay for our life of ease. If I have to choose between a 3MI, Chernobyl, and Fukushima spread over 40 years, and a Kingston, Macondo, Valdez, Fergana Valley, Ixtoc, Chevron Richmond - you know, the list of fossil fuel accidents affecting tens of thousands of people is just too long to go through. Nevermind the occasional train derailment and fire.

You design things as best you can against the problems you can think of, and you design mitigation plans against the ones you can't. Every time a new problem comes up, you improve the design. You can not live in a perfectly safe world. If you use electricity, you could shock yourself. If someone produces electricity, they could blow up. If you don't use electricity, a grue might eat you in the dark. Choose your risk, but try to be rational about it. There's nothing inherently worse about the nuclear boogeyman than the coal boogeyman, except that you've been living with the coal boogeyman for 2000 years.

Best Solution

[NEDHead]

If they could capture the water from the tailpipe, gather the CO2 from the air, and use a windmill on the roof of the car to generate the power to make the fuel, they could DRIVE FOREVER!!!

Re:Best Solution

[whopis]

My God man. If you were to do that, you would have a car that not only would drive forever, but it would generate more energy that it used.

Clearly that would cause the car to never be able to stop, and always continue increasing in velocity.

Your vision ends with a world covered in cars that driving all around forever, asymptotically approaching the speed of light.

Is that really the world we want to live in?

Re:So they've invented the plant?

[freeze128]

It's spelled "LAWN".

Re:Not enough resourcees

[Amigan]

Ethanol was going to save us. Then farmers / growers sold all their corn to ethanol producers, and the food chain suffered as feed for animals got more expensive, exports to 3rd world fell, and food riots started...

Re:Not impressed - make food with water, CO2 &

[Hognoxious]

why don't they stop at hydrogen? It's a great fuel

It's not a great fuel. It leaks, because the molecules are so small. It causes some metals to go brittle.

You can get round these problems by sticking it to chains of carbon. A convenient side effect of that is it makes it compatible with existing engines & distribution infrastructure .

Re:So they've invented the plant?

[DaChesserCat]

Not really. Plant metabolism is usually < 10% efficient at turning sunlight, CO2 and water into useful biomass. And the process for turning useful biomass into hydrocarbon fuels is < 100% efficient, so solar -> fuel is very low.

In their case, they're using intermittent power, from wind and solar, to do a modified Sabatier reaction and make methanol, which then goes into an integrated Fischer-Tropsch process to make longer-chain hydrocarbons.

The resulting solar -> fuel conversion efficiency is HIGHER than going through biomass production.

Re:Not enough resourcees

[Jeremi]

There isn't enough CO2 in the atmosphere to make this work.

That's okay, because they are unlikely to be taking the CO2 out of the atmosphere anyway. It would be much cheaper and easier to capture and reuse the outputs of an existing CO2 source (e.g. a coal plant) than it would be to suck CO2 out of the ambient air.

Soda

[unixcorn]

Shoot, now there will be a CO2 shortage and my soda will be flat.