Patent Application
20240409832
Performance requirements for automobiles and trucks are becoming increasingly restrictive regarding properties of combustion: net CO2 and criteria emissions—CO, NOx and PM2.5. Although light-weight and short-range passenger vehicles may best be powered by electricity, trucks and many other applications require long range and the ability to transport heavy loads. Trucks as well as all other modes of transport can effectively meet the new emission requirements using low-cost, renewable methanol-ethanol blend fuels of our present invention. Preferably, our methanol-ethanol blend fuels will be used in engines operating at higher-than-usual compression ratios. Spark ignition engines may effectively operate at a broad range of compression ratios with our new fuel. Compression ratios of 10 to 18 may be used. Our new methanol-ethanol blend fuel may also be utilized in compression-ignition engines of high compression operating on the thermodynamic principles of the General Cycle as described in U.S. Pat. No. 11,454,165. Our fuel blends, when used in General Cycle engines, can provide higher power output efficiencies than have been available here-to-fore.
Our non-fossil fuel blends comprising methanol and ethanol optionally with water and other additives are among the best sustainable fuels due to their combined benefits of least cost and low emissions. An alcohol-blend fuel comprising these alcohols is compatible with existing fueling infrastructure and fuel-injection systems and is easy to manufacture by existing processes from almost any kind of waste. Our analysis has shown that General Cycle engines of suitable design show promise to perform at the highest efficiency—in some cases as high as 58% to 60%—when using our alcohol-blend fuels.
Prior research to develop clean fuels with low carbon emissions have concentrated in two areas: (1) gradual transition from fossil fuels by blending renewable fuels with fossil fuels, and (2) use of unblended fuel compounds, or a single fuel compound such as methanol with only small amounts of additives to control rheologic, corrosion, or ignition properties. A recent “Co-Optima” research program directed by the United States Department of Energy is illustrative of this focus on either unblended fuel compounds or blending them with fossil fuels. The final summary report of this research includes the following statement: “Jump-Starting Viable Solutions with Foundational Research—Co-Optima set out to make dramatic improvements to fuels and engines by examining the two research areas in tandem. By focusing on the fuel properties of bioblendstocks—components designed to be blended into gasoline or diesel fuel—in relation to a range of combustion strategies, the initiative discovered ways to deliver greater efficiency and lower emissions with both conventional and advanced engines.” While this research program refers to so-called “advanced engines”, in reality, only modification of combustion strategies to current engines were considered, and there were no example engines that were designed specifically to operate on renewable fuels such as alcohols.
However, engines are already being built to run on alcohols in two instances. First, several companies that build ship engines are building “dual-fueled” engines that can use either conventional bunker fuels or alternatively can use methanol in combination with bunker fuel. Secondly, light-duty vehicles such as cars and delivery vans may use methanol for fuel (primarily in China), or ethanol for fuel (primarily in Brazil). In the United States, there are “flex-fuel” cars that can operate either on gasoline or gasoline mixed with ethanol at up to 85 percent ethanol. This fuel is commonly called “E85 gasoline.” Also, Scania in Sweden manufactures trucks having compression-ignition engines that use ethanol for fuel, with a small amount of additives. In none of these cases is a substantial blend of renewable alcohols or other compounds used for fuel. It is important to point out that while the Co-Optima research looked at blending bio-fuels with fossil fuels, it did not cover fuel blends of only different types of bio-fuels, such as the alcohol blend fuels of our invention.
Thus we see that no other company or persons, save ourselves, have designed an engine for the purpose of operating on a blend of renewable fuels, nor has anyone planned to produce a renewable fuel comprising a blend of renewable alcohols that would be used in such an engine.
The best renewable fuels will have: (1) low cost, (2) production at high volume, (3) lowest emissions, (4) high process lifecycle efficiency, (5) low environmental impact in case of an accidental spill, and (6) minimal impact on transport norms. When we compare various possible renewable fuels regarding cost and net carbon emissions, we have found that methanol and ethanol are among the best sustainable fuels due to their combined benefits of least cost and low emissions. Further benefits can be realized by blending these two alcohols optionally in combination with other renewable components.
These alcohols and their blends fit all six requirements listed above. They can be used over a broad range of engine applications in transportation, heavy equipment, stationary engines, and combined heat and power (such as electric power generation with industrial process heat). But keep in mind that the engines will perform optimally only as they are designed or adapted for use with alcohol-blend fuels.
Right now, billions of dollars are being spent worldwide to ramp up production of renewable fuels. For these new fuels, three serious limiting problems stand out: (1) price, (2) adequate feedstocks, and (3) engines suited to use the new fuels. The problems are most acute for engines of all sizes used in shipping of goods for great distances. All of the practical kinds of renewable fuel will be needed to satisfy fuel demands in future years. According to the International Energy Administration, ships will use 1.69 billion barrels of bunker fuel in 2023, with use continuing to rise at 1% a year, reaching 1.71 billion barrels (72 billion gallons) in 2024, which is more than double the entire world output of all renewable fuels! The fuel need for large on-shore engines is even greater. For example, the U.S. alone consumed 1.42 billion barrels of ultra-low-sulfur diesel fuel in 2021, a great part of which was used by heavy trucks.
Production of renewable fuels derived from agricultural crops and waste oils or fats—biodiesel, synthetic diesel, sustainable aviation fuel (SAF), and corn ethanol—are limited by the availability of biomass feedstocks. On the other hand, alcohols can be produced from a broad spectrum of waste. Methanol is easily produced from off-hour surplus electricity and “waste” CO2 emitted from point sources. More than 80 renewable methanol plants are under construction at the present time. While a substantial manufacturing capacity for renewable ethanol is available for current needs, future ethanol production may be limited by biomass feedstocks. On the other hand, renewable methanol production is poised to ramp-up, exceeding ethanol for fuel use.
Table 1 projects world production of liquid fuels in 2027. It shows that for the next several years the predominant supply of renewable liquid fuels consists of alcohols, yet they can only supply a small fraction of the amount needed to replace diesel fuel. We will show that a methanol-ethanol blend fuel can substantially increase the available supply of clean, renewable liquid fuel in the near future.
Table 1 also clearly shows the disparity between availability of the predominant renewable fuels and the size of the demand indicated by production of present fossil fuels. By 2050, gasoline may be replaced by battery power in light vehicles. However, combining methanol and ethanol together into a single fuel system can more readily supply the greater power needed for decarbonizing heavy transportation—trucks, trains, and ships. Our methanol-ethanol fuels are suitable for any desired transportation use. As will be explained below, methanol production can be increased more than most other fuels, and combining it with production of ethanol results in a substantial increase in renewable fuel production while concomitantly reducing net CO2 emissions.
Because of the acute disparity between renewable fuel supply and the great need described above, an important purpose for our invention is to obtain the maximum work from the energy value of the fuel. This is best accomplished by using our fuel in high-compression engines. The highest efficiency will be achieved by use of our methanol-ethanol blend fuels in compression ignition (CI) engines that operate according to the principles of the General Cycle. The low cetane numbers of methanol and ethanol do not naturally suit themselves to CI engine operation. Fortunately, four methods are already established to correct this problem:
The first two methods can provide exceptional power and efficiency when used with methanol-ethanol blend fuels in CI engines. An example engine having an increased compression ratio will be described below.
The fuel compositions of the present invention contain methanol and ethanol. While it is presumed that these alcohols are from renewable sources, this is not a requirement for our invention. Other optional elements of our inventive fuel may comprise:
A small amount of physical property improvers to promote the lubricity of the fuel. Examples are glycerol and PEG polymer. These compounds provide better flow properties and decrease wear on fuel handling parts in the engine, such as fuel pumps and injectors.
Cetane improvers for enhanced ignition. Some renewable ignition improvers that may be utilized in our present invention are: dimethyl ether (DME), methylethyl ether, diethyl ether, 2-methoxyethyl ether, ammonium nitrate, and 2-ethylhexyl nitrate.
A quantity of water, from one percent up to approximately 25 percent.
Advantages of Methanol-Ethanol Blend Fuels—(2) Methanol-Ethanol Blend Fuels have Lowest Renewable Fuel Cost
Five example fuel components will be described to show how they affect cost and performance of our methanol-ethanol blend fuels:
Note in Table 2 the exceptionally high energy value of 219,000 BTU assigned to one dollar's worth of added water. This high energy value results from the very low cost of water and a small increase in engine efficiency that water provides. In reality, the benefit of a small amount of water in alcohol fuels is far greater than this assigned value. This results from a reduced cost to manufacture alcohols obtained by leaving some water in them. Corn ethanol producers go to great expense to remove water from their product. This is needed to mix the ethanol with gasoline. The majority of this expense can be eliminated when using the ethanol as a component of a purely alcohol blend fuel, in which water is a beneficial component. For making our renewable alcohol blend fuel, the expensive water removal step in ethanol production can be omitted. This provides a substantial cost saving in the making of ethanol. It has been known for some time that water in a fuel increases power and efficiency. A good, economical point in ethanol distillation would leave about 10% water in the product.
Renewable methanol, or “green methanol,” is now being produced at close to the same prices as methanol made from natural gas or coal. For comparison, ULSD diesel fuel provides 52,660 BTU per dollar at the current (May 2023) L.A. benchmark price of $2.44 a gallon.
Of these potential fuel components, methanol and DME can be made at moderate cost from CO2 and electricity as well as from biomass. Glycerol is a low-value byproduct from biodiesel production that improves physical properties of alcohols, making them work better in pumps and injectors. Three of these fuel ingredients, methanol, ethanol, and glycerol, are available in substantial quantity and at low cost.
A comparison of cost and heat input is only half of the story. The energy output of the engine is equally important and that depends on the engine's (and fuel's) efficiency. Consider the following chemical equation for combustion of methanol in air:
In this reaction the number of gas molecules changes from 14.3 to 17.3. This change in number of gas molecules causes an increase in engine efficiency. All oxygen-bearing fuel components have this property. If one examines the above reaction with water added to the fuel, it will be seen that this molar increase in gas products increases further, providing an additional efficiency increase.
Also it is well known that oxygen-carrying fuels and additives increase engine power. Thus our methanol-ethanol blend fuels may provide higher power, and efficiency improvement of a few percent to as much as 10% higher than for present fossil fuels, depending on engine construction. Our research has shown that a General Cycle engine with a higher compression ratio, near 24.5 or higher, will run smoothly on our alcohol blend fuels. Benefits of combining optimal engine design and molar increase can raise engine efficiency to approximately 58% to 60% for our methanol-ethanol blend fuels, compared to 30% to 51% in the present art. Efficiency can play a tremendous role in the amount of renewable fuel needed to operate the world economy. A 50% improvement in efficiency could yield the economic equivalent of a 33% reduction in fuel costs.
Advantages of Methanol-Ethanol Blend Fuels—(4) Blending Methanol with Ethanol Lowers Carbon Intensity and Increases Renewable Fuel Output
Production of ethanol is a two-step process. First, cellulosic biomass can be converted into sugars by breaking down the cellulose and hemicellulose components of the biomass using chemical or enzymatic methods. Similarly, plant starches are converted to sugars using amylolytic enzymes. The second step is conversion of sugars to ethanol by fermentation. In this fermentation step, a sugar molecule is converted into one molecule of ethanol and one molecule of CO2:
½C6H12O6→CH3CH2OH+CO2
Methanol can be made from this CO2 molecule by reacting it with green hydrogen (produced by electrolysis):
CO2+3H2→CH3OH+H2O
Combining both of these processes in one facility would increase fuel production from biomass by as much as 70% and cut the plant's CO2 output to near zero. By exercise of our invention, these alcohols may be blended to form a superior, lower-carbon fuel. One may add another step—the dehydration reaction, converting methanol to dimethyl ether, or DME:
2CH3OH→CH3—O-CH3+H2O
Imagine a biofuel factory utilizing all three reactions, beginning with a biomass feedstock and “waste” electricity, and producing a fuel blend of ethanol, methanol, and dimethyl ether. All three mix well with each other. DME can also be produced directly from virtually any carbon-containing biomass or waste material. DME is miscible with methanol, ethanol, and water and is a useful optional additive for adjusting ignition properties of our methanol-ethanol blend fuel.
Oil and coal make a mess wherever they fall on the landscape and in their processing to useful products. Natural gas pollutes in the fracking and extraction process, or as it leaks into the atmosphere. But our new fuel mixes with water and if it leaks out on the land or into water, it quickly dissipates, either by evaporation, or it dissolves in water and degrades-no mess is left.
It is well known that methanol and ethanol burn very efficiently under a variety of conditions. Methanol-ethanol blend fuels burn with a clear, clean flame in open air for many fuel compositions, and they burn with corresponding clean exhaust in engines. These fuels have a high oxygen content and low flame temperatures which contribute to lower NOx formation. Additionally, the full cycle carbon intensity of our methanol-ethanol fuels is lower than that of machines powered by lithium batteries and even lower than vehicles powered by hydrogen fuel cells. This is a consequence of the high carbon intensity of lithium batteries and of grid electricity.
The efficiency values of methanol-ethanol blend fuels are greater than for fossil hydrocarbon fuels, gasoline and diesel fuel, in high-compression engines, and in particular in high compression engines operating according to the General Cycle. This is because of the oxygen carried by the fuel and a molar increase in the combustion as has been explained. This is not to suggest that one gets greater power output per gallon; in fact the energy content of our alcohol blend fuels is roughly half that of fossil fuels. But the energy content going in versus the energy flowing out of the engine (the definition of efficiency) is better for alcohol-blend fuels.
Our methanol-ethanol blend fuel can be the path to a low-carbon, clean-fuel-powered economy. The exact desired fuel composition for any engine application will be a combination of methanol, ethanol, water, and other optional additives. The proportions of these components can vary over a wide range. There are many types of engines and applications for our new fuel compositions. Each type of internal combustion engine and application may benefit from a specific renewable fuel blend. We conceive of compositions for our new methanol-ethanol blend fuels falling within the following bounds of composition:
Our methanol-ethanol blend fuels when combined with high-compression engines constitute a substantial improvement over the commonly-employed renewable power sources, which are lithium batteries or hydrogen fuel cells. Our new fuel compositions are found to have the following property ranges, shown alongside properties of liquid hydrogen fuel and also lithium battery properties in Table 3:
Thus we see that our methanol-ethanol blend fuel has a substantially higher energy density than competing renewable energy sources, although somewhat less than—approximately one-half—the energy density of today's gasoline, which has 114,760 BTU per gallon.
Our alcohol-blend fuel is preferably absent of any fossil hydrocarbon fraction. This is to eliminate separation of the fuel due to the presence of water. In no instance do we believe that a presence of more than 15% fossil hydrocarbons creates a preferable alcohol fuel blend.
A methanol-ethanol blend fuel has many other general properties that are substantial improvements over those of other energy choices:
As a further elucidation of how our methanol-ethanol fuel may be applied, we will now describe a specific methanol-ethanol blend fuel composition for use with a General Cycle engine such as the one described above. This example fuel, referred to as “MERF” (Methanol-Ethanol Renewable Fuel) has the following composition:
Using the costs and other properties given above, this low-cost renewable fuel is estimated to have the following characteristics:
Our methanol-ethanol blend fuels generally have high octane values, in the range of 90 to 140, unless ignition accelerators are included. Compression ratios of 10 to 18 may be used, with a compression ratio of 15 being highly preferred. Spark ignition engines with compression ratios as high as 18 may be used to obtain exceptionally high engine efficiency. Of particular importance is the application of our methanol-ethanol blend fuels to operation in CI engines operating according to the principles of the General Cycle. For such engines, compression ratios as much as 24.5 or even higher are desirable.
For an alcohol-blend fueled CI engine, a major purpose of a high compression ratio is to achieve sufficient temperature and pressure due to compression that the alcohol blend fuel will readily ignite when it is injected. A compression ratio of 24.5 or greater is required for our methanol-ethanol blend fuels without cetane improvers. Lower compression ratios may be used as cetane improvers are added. Our General Cycle engine described in U.S. Pat. No. 11,454,165 demonstrates that higher efficiencies may be gained at compression ratios of 19 or greater when combined with an Atkinson ratio greater than 1.0. Preferable Atkinson ratios are in the range of 1.1 to 1.6, with peak efficiencies at 1.3 to 1.4 depending on the particular engine and fuel parameters.
The following described General Cycle engine in Table 4 is of a particular design for operation with a methanol-ethanol blend fuel of the present invention.
While an alcohol blend fuel may be developed that works in an engine of conventional prior art design, constructing an engine to use the methanol-ethanol blend fuel of our present invention is the preferable path to net-zero carbon emissions and superior engine efficiency. We believe that fuel design and engine design go hand-in-hand. It is a self-imposed limitation to only fit a fuel to a particular engine, and we dispense with this thinking.
This application claims the benefit of U.S. Provisional Patent Application No. 63/507,087 filed Jun. 8, 2023.
| Number | Date | Country | |
|---|---|---|---|
| 63507087 | Jun 2023 | US |
