Efficiently Producing Fuels from Waste CO2 and Off-peak Wind or Other Renewable Energy

The WindFuels™ Primer
- Basic Explanation for the Non-scientist

The WindFuels™ Basic Process Explanations.
WindFuels™. Now that is a word you have not heard before. So what are WindFuels™? The concept is really not complicated. We will use energy generated by wind to power processes that will recycle waste carbon dioxide into transportation fuels for automobiles, like diesel, ethanol or gasoline. We can also make fuels like jet fuel and propane. (We are talking mostly about fuels, but the FTS process can also produce ethylene and propylene which are used to make plastics – used in everything from textiles to tables.)

We'll recycle CO2 from power plants or other exhausts (which release CO2into the air, contributing to global warming). Because we have removed the CO2 from the air to make the fuels, using (burning) WindFuels releases no new carbon, making it a carbon neutral process. Replacing oil with WindFuels will reduce total CO2 emissions by 40%.

No experienced chemist has doubted that it is possible to convert CO2 to fuels. The problem has been that prior proposals for doing this conversion have had efficiencies of only 20% to 30%.

The combination of the eight major technical advances we have made over the past five years will now permit this conversion to be done at 60% efficiency. That’s high enough for carbon-neutral fuels made from waste CO2 to easily compete with petroleum on a cost basis, especially when the input energy is from excess wind energy in the middle of the night.

What we are doing is not magic. It is just good chemistry, physics, and engineering. Because we are using the carbon from waste CO2 rather than coal, we have to add a lot of energy from wind. However, when all the processes are properly optimized, the cost of this energy becomes affordable. It is a small price to pay to dramatically reduce greenhouse gases in the atmosphere and provide a limitless supply of clean transportation fuels.

Fuels like ethanol, gasoline and jet fuel are hydrocarbon fuels. Hydrocarbons and alcohols are chemicals that contain hydrogen (H), carbon (C) and oxygen (O). We will use water (H2O) and the waste (polluting) carbon dioxide (CO2) from power-plant smokestacks to provide the carbon, oxygen, and hydrogen needed to make fuels like ethanol (C2H5OH) and gasoline (C8H18).

Here's How: (Later on this page, we’ll explain each of these processes - and we will try to explain them in a clear way.)

Wind Farms

1. Wind Farms generate electricity for electrolysis and other processes.
2. Electrolysis is the process in which electric current is passed through water (H2O) to break the bonds between the hydrogen and the oxygen, yielding hydrogen (H2) and Oxygen (O2).
RWGS & FTS Plant
3. Reverse Water Gas Shift (RWGS) is used to produce carbon monoxide (CO) from carbon dioxide (CO2).
4. In a widely used process called Fischer Tropsch Synthesis (FTS), the liquid fuel production from hydrogen (H) and carbon monoxide (CO) occurs.


5. The resulting products will fuel our cars, trucks or jet planes and are:

Carbon neutral (WindFuels do not release new CO2 into the air. The carbon was recycled from exhausts.)

Renewable (Both wind and CO2 are replaced. In contrast – oil and coal which are used up are not renewable.)

Economical (competes on a price basis)

Contributing to Energy Independence!

Overview of FTS (Fischer Tropsch Synthesis)

The liquid fuel production from hydrogen, carbon, and oxygen occurs in the Fischer Tropsch (FT) reactor. FTS has been used in commercial production of liquid fuels of all types from coal or natural gas (gas) for over 60 years. FTS was used in Germany during WWII to generate fuels when crude oil was scarce, so the process is not new. The process has not been used much in the United States because oil was cheap and plentiful. Utilization of the FTS processes has been increasing, as coal and gas are now much cheaper than oil. (If we use waste CO2 in place of gas or coal in FTS, we can supply fuel and reduce the CO2 in the air.)

The FTS process uses catalysts to efficiently convert a feed mixture of carbon monoxide (CO) and hydrogen (H2) to hydrocarbons of all types. Different catalysts and different operating conditions can help “select” for higher yields of some hydrocarbons than others, but there will always be a mixture of different products created by the reaction:

In conventional FTS, the syngas is obtained from high-temperature reforming of coal or methane. Usually, the FT catalysts and conditions (pressure, temperature, and mixture) have been chosen to obtain mostly gasoline, diesel, and waxes from the FT reactor. Recent progress in the catalysts and conditions now allow high yields of ethanol, propanol, and butanol also.

Getting clean hydrogen - Electrolysis
Electrolysis is used rather than fossil fuels to generate the hydrogen for our WindFuels. Electrolysis is the process in which electric current is passed through water (H2O) to break the bonds between the hydrogen and the oxygen, yielding hydrogen (H2) and Oxygen (O2).

Electrolyzers for efficiently splitting water into high purity hydrogen and oxygen have been in industrial production for decades. A solution of potassium hydroxide (KOH) in water is used because it has low resistivity and thus lower power loss. The addition of electrons at the negative electrode (also called the cathode) produces hydrogen gas (H2) and hydroxyl ions (OH-), which remain in the solution. At the positive electrode (also called the anode), electrons are removed from OH- ions, producing water (H2O) and oxygen (O2). A membrane that is permeable to the OH- ions (and possibly to water too) separates the two electrodes to keep the gases from mixing while allowing the electrical current to flow through it on the charge carriers. In practice, the solutions on both sides are continually flowing to maintain the desired salt concentrations. The two gases produced also contain a lot of water vapor (which is easily separated) but only minute traces (easily under 0.1%, and sometimes under 0.01%) of other impurities (primarily the other major gas, either O2 or H2).

Efficiency of commercially available 2 MW (megawatt) electrolyzers has typically been 73%. Laboratory experiments have exceeded 85% at higher pressures and lower current densities, and we have shown that the waste heat (at 160 0C) can be utilized at 30% efficiency. Total system efficiency of a 250 MW electrolysis system may eventually approach 90%.

A quick note about water, the FTS process will require about 5 gallons of water for every 3-4 gallons of produced fuels, which is at least an order of magnitude less than the water requirements for biofuels. Using reverse-osmosis, water sources as impure as seawater can be used, which would add only $0.01/gallon to the cost of the fuel produced. Water will not be a limitation.

Getting the CO: The Reverse Water Gas Shift (RWGS)
The next step is to efficiently get the carbon monoxide (CO) needed in the syngas from CO2. There is a very robust and efficient reaction that has been known for the past century as the water gas shift reaction (WGS). This is used in fossil-fuels FTS to generate hydrogen by combining CO (from fossil fuels) with steam at high temperatures (400-800 0C) to form hydrogen and carbon dioxide.

The fossil fuels FTS systems have no trouble getting carbon monoxide, and use excess carbon monoxide to get the hydrogen they need for proper syngas mixtures. The reverse is true for clean, renewable WindFuels. Through electrolysis, we can efficiently get all the H2 we need, but we need an efficient way of getting the CO.

The reverse of WGS reaction, known as the reverse water gas shift (RWGS) provides a robust method of producing CO and water from CO2 and H2.

Getting this reaction to achieve high yield of CO at high efficiency with low production of unwanted methane (CH4) has previously been a challenge, but we have shown elsewhere in detail how this can now be achieved achieved at very high efficiency.

The syngas (remember, the CO plus H2 mixture) then goes to the FT reactor, where it is adsorbed onto the surface of the catalysts (often small metal particles), where it is reformed into hydrocarbons (such as gasoline, propane, and diesel), alcohols (including ethanol and propanol), water, and waste heat. As these reactions are exothermic (heat is released), they proceed readily. The reaction efficiencies here are in the range of 70-85%, depending on the compound that is formed, with the higher efficiencies being for the light alcohols (methanol and ethanol). We have shown elsewhere in detail how the waste heat from the reactor can be utilized at over 40% efficiency.

The output from the FT reactor includes the desired products (alcohols, jet fuel, propane, etc.) along with a lot of unreacted inputs (CO and H2) and some undesired products – water, CO2, and methane. One of the most important keys to achieving high system efficiency is devising extremely efficient methods of separating and recycling the unwanted components. We have developed important improvements in separations and recycling. Elsewhere we have shown how this can be done.

Fossil-Based FTS is dirty. Windfuels are a path to true Global Warming Mitigation.
The biggest problem with fossil-based FTS is that an enormous amount of polluting CO2 is released – especially if coal is used. For every kg of coal used for coal-to-liquids (CTL) diesel, 2.2 kg of CO2 are emitted and 0.3 kg of fuel is produced. (Even NG-based FTS results in about 25% more CO2 total release than simply using conventional oil.) WindFuels uses similar FTS processes, but begins with carbon-neutral “syngas” (the feed mixture of CO and H2) made from water (H2O) and waste CO2 (from coal plants). This can be done at very high efficiency with zero net carbon release, as we show in detail elsewhere on this website and summarize below.

Below: Since the CO2 was removed from the air (or smokestacks) to make the WindFuels, no new CO2 has been released. The carbon was recycled. The net carbon from WindFuels is zero.

Some may say that the CO2 from coal is eventually released, and this is therefore not carbon neutral. However, many of those same people have probably either bought carbon offsets or at least looked into the idea. The principle of carbon offsets is to reduce carbon emissions elsewhere to offset the carbon you are generating. Well, the coal from the coal power plants (which provides electricity to hundreds of millions of homes) emits billions of tons of CO2. If we recycle that CO2 to produce WindFuels, it will still eventually be emitted, but oil and natural gas – as well as much more environmentally destructive fuels such as coal-to-methanol, tar-sands fuels, and oil-shale fuels – are NOT burned and are therefore NOT emitting CO2which reduces overall greenhouse gas emissions.

Eventually, the CO2 can be taken from the atmosphere rather than from smokestacks, but that will be more expensive. Today, using CO2 from the atmosphere might make the WindFuels 40% more expensive. Thirty years from now, we’ll probably be able to do it for just an 8% cost penalty. We can’t wait 30 years to get started. We'll start with CO2 from smokestacks.

Perfectly Solving the Grid Stability Challenge.
We’ve all probably heard it will not be possible to stabilize the power grid if much more wind energy is added, and the result would be frequent regional grid failures and blackouts. Without a solution to the energy storage problem, that would be true. The electric grid stability challenge arises from changes in grid supply (power plants, wind, and solar) not being able to follow the changes in grid demand (from users) quickly enough. Wind power is often greater in the middle of the night when demand is minimal. “Clean coal”, nuclear, and many of the older natural gas power plants take many hours to turn down, and there is not a cost effective method of storing energy other than pumped hydro storage, which is not an option in most areas. (Compressed air energy storage, CAES, will be either very expensive or quite inefficient.)

WindFuels will only draw power during off-peak hours when there is excess renewable energy available at very low cost. Off-peak power rates are often under 15% of peak rates to encourage more use of it. The WindFuels electrolyzer can respond within milliseconds to changes in supply and demand. It will completely solve the grid stability problem by storing the excess peak grid energy temporarily in compressed hydrogen and then converting it to liquid fuels (which are easily stored and distributed) at a fairly steady rate around the clock. Storing enormous amounts of energy in hydrogen is considerably more expensive than storing energy in liquid fuels, but storing enough hydrogen to keep the FTS plant going steadily around the clock (to efficiently convert the hydrogen to liquid fuels) will not be either too expensive or too risky.

Improving the competitiveness of fuels from CO2.
The Windfuels process seems unquestionable destined to be the dominant, sustainable solution for transportation fuels in the future, but electrolyzers today are still expensive. Hence, the capital outlay for the electrolyzers (for perhaps the next five years) may be beyond what most investors wish to consider in today’s risk-averse world.

That has motivated us to begin developing a less expensive “bridging” approach to synthesizing fuels from a combination of CO2, methane (from shale gas), water, and renewable energy. The outcome of this research is a process we have dubbed CARMA-GTL, for Carbon dioxide Advanced Reforming of Methane Adiabatically, with GTL. As explained in a paper recently presented at the national ACS meeting, as long as low-cost natural gas is available, our CARMA-GTL process reduces the electrolyzer requirements by a factor of three to ten while actually increasing plant efficiency. Since most of the carbon in these fuels comes from shale gas (only a minor fraction comes from CO2), these fuels are only slightly carbon neutral (like most biofuels). However, the CARMA-GTL plants will be much less expensive than Windfuels plants, and they will be able to steadily transition to using more renewable energy and less shale gas. Developing this technology will begin to drive the cost of electrolyzers down and allow investors to become more comfortable with coming Windfuels paradigm.

Western Research Institute's
Test Fischer Tropsch System




Better than sequestration?

Sequestering a ton of CO2 prevents one ton of CO2 from being emitted into the atmosphere, adding a significant cost burden.

Pumping one ton of CO2 into a WindFuels plant would profitably create about 170 gallons of liquid fuels (~0.56 tons), which keeps additional fossil fuels from being consumed .

Since the CO2 is removed from the air (or smokestacks) to make the WindFuels, no new CO2 has been released. The net carbon from WindFuels is essentially zero.

Net CO2
added to the atmosphere
for 1 ton of various liquid fuels:

0.2 tons
Ethanol from established corn fields
2.9 tons
Conventional Oil
4.4 tons
Deep Sea Oil
5.3 tons
Heavy Oil
5.7 tons
Oil Shale, ICP
6.0 tons
Tar Sands
6.0 tons
Oil Shale, ATP
6.5 tons
10 tons

Shockingly, newly plowed grasslands converted to crops releases tons of CO2

(see Science 319, 1235-1238, Mar 21, 2008.)

We are using wind energy because it is the most cost effective renewable power source in the United States. In some countries, another renewable energy source like solar or geo-thermal would be more appropriate.






















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