Energy conversion & chemical fuels

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Liquid fuels, due to their high energy densities, are currently the only practicable way of powering aircraft, and many other applications. However at present most liquid fuels are petroleum-based fossil fuels.

A major limitation of intermittent renewables, especially solar and wind energy, is the difficulty of storing energy when they produce it to use when it is needed. Also - particularly in the case of solar power - the areas it can most readily be produced are remote from the regions where it is most wanted and transporting it it a problem.

Efficient and economical conversion of low-carbon electricity to energy-dense chemical fuels - or even production of such fuels directly from solar or other low-carbon energy sources - is vital to de-carbonising much of our energy usage.


Hydrogen Production Wikipedia

Hydrogen production is the family of industrial methods for generating hydrogen. Currently the dominant technology for direct production is steam reforming from hydrocarbons. Many other methods are known including electrolysis and thermolysis.

The Hydrogen Economy Suzanna Hinson; Climate Answers; 6 Apr 2017

Discusses various means of producing H
  • Steam reforming: the vast majority of hydrogen produced today is through steam reforming. The fossil fuel source (usually methane) mixes with steam at high temperature and pressure and, using a nickel catalyst, it forms hydrogen and carbon dioxide. This process is currently two to three times more expensive than fossil fuels.
  • Partial oxidation: is similar to steam reforming but also requires oxygen. Partial oxidation can be used for other hydrocarbons including oil and coal. Although the efficiency is lower than with steam reforming the use of this process will depend on what natural reserves a country has – e.g. coal.
  • Water electrolysis: requires large amounts of electricity to split water molecules. However it may be a way of using surplus renewable power rather than overload the grid. Photoelectrolysis is a new technology that achieves the same results but using a solar cell rather than electricity.
  • Biological production: many species such as algae and bacteria produce hydrogen naturally through photosynthesis and fermentation but this is yet to become a commercial process.
and storage and usage of Hydrogen, mentioning the UK's [[H
1 Leeds City Gate]] project

Hydrogen from Water

Hydrogen can be produced from water by electrolysis. This approach is used in the Hebrides electricity to hydrogen project.


Hydrogen Production Using Nuclear Energy IEAE; 2013

Overview of the role of Hydrogen in the World's present and possible future energy mix, and discussions of programmes for nuclear production of Hydrogen in various countries, methods of production including the use of nuclear energy, applicability of various types of reactors, safety issues, and economics.

Nuclear Hydrogen Production Technology IEAE

Brief discussion of use of nuclear energy for Hydrogen production

Hydrogen is an environmentally friendly energy carrier that, unlike electricity, can be stored in large quantities. It can be converted into electricity in fuel cells, with only heat and water as by-products. It is also compatible with combustion turbines and reciprocating engines to produce power with nearzero emission of pollutants. Therefore, hydrogen could play a major role in energy systems and serve all sectors of the economy, substituting for fossil fuels and helping mitigate global warming.

Nuclear energy, in addition to its application for producing electricity, can also be used to generate hydrogen for direct use by energy consumers. Generating hydrogen using nuclear energy has important potential advantages over other processes. For example, it requires no fossil fuels, results in lower greenhouse-gas emissions and other pollutants, and can lend itself to large-scale production. As a greenhouse-gas-free alternative, methods of using nuclear energy to produce hydrogen from water by electrolysis, thermochemical, and hybrid processes are being explored. This paper briefly describes these three different processes.

Nuclear power plants can produce hydrogen to fuel the “hydrogen economy” American Chemical Society; 25 Mar 2012

Speaking at the 243rd National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society, Ibrahim Khamis, Ph.D., described how heat from existing nuclear plants could be used in the more economical production of hydrogen, with future plants custom-built for hydrogen production. He is with the International Atomic Energy Agency (IAEA) in Vienna, Austria.

SLAC / UToronto Catalyst

New Catalyst Lets Us Store the Power of the Sun Todd Jaquith; futurism; 29 Mar 2016

Scientists have found a way to “crack” water three times more efficiently using solar- and wind-generated electricity, which means it’s possible to store renewable energy for later use.

to Hydrocarbons

There are processes being investigated and developed for generating ethanol, methanol, methane (Natural Gas) and other hydrocarbons (and mixes of HCs) from CO

The sources of CO
can be atmospheric, concentrated CO
from industrial processes (such as cement production or carbon capture from combustion), or CO
dissolved in water (generally seawater). All processes require energy to drive them; this is usually electrical.


Steering CO2 hydrogenation toward C–C coupling to hydrocarbons using porous organic polymer/metal interfaces Chengshuang Zhou et al; PNAS; 15 Feb 2022

The conversion of CO2 into fuels and chemicals is an attractive option for mitigating CO2 emissions. Controlling the selectivity of this process is beneficial to produce desirable liquid fuels, but C–C coupling is a limiting step in the reaction that requires high pressures. Here, we propose a strategy to favor C–C coupling on a supported Ru/TiO2 catalyst by encapsulating it within the polymer layers of an imine-based porous organic polymer that controls its selectivity. Such polymer confinement modifies the CO2 hydrogenation behavior of the Ru surface, significantly enhancing the C2+ production turnover frequency by 10-fold. We demonstrate that the polymer layers affect the adsorption of reactants and intermediates while being stable under the demanding reaction conditions. Our findings highlight the promising opportunity of using polymer/metal interfaces for the rational engineering of active sites and as a general tool for controlling selective transformations in supported catalyst systems.

in seawater to aircraft fuel - US Navy

Scale Model WWII Craft Takes Flight With Fuel From the Sea Concept US Naval Research Laboratory; 7 Apr 2014 (via Internet Archive Wayback Machine)

Navy researchers at the U.S. Naval Research Laboratory (NRL), Materials Science and Technology Division, demonstrate proof-of-concept of novel NRL technologies developed for the recovery of carbon dioxide (CO
) and hydrogen (H
) from seawater and conversion to a liquid hydrocarbon fuel. Fueled by a liquid hydrocarbon—a component of NRL's novel gas-to-liquid (GTL) process that uses CO
and H
as feedstock—the research team demonstrated sustained flight of a radio-controlled (RC) P-51 replica of the legendary Red Tail Squadron, powered by an off-the-shelf (OTS) and unmodified two-stroke internal combustion engine. Using an innovative and proprietary NRL electrolytic cation exchange module (E-CEM), both dissolved and bound CO
are removed from seawater at 92 percent efficiency by re-equilibrating carbonate and bicarbonate to CO
and simultaneously producing H
. The gases are then converted to liquid hydrocarbons by a metal catalyst in a reactor system.

Fuel from Seawater? What's the Catch? Don Willmott; Smithsonian Magazine; 6 Dec 2014

Scientists at the U.S. Naval Research Laboratory recently flew a model plane using a liquid hydrocarbon fuel they sourced from the ocean

Zero emission synfuel from seawater John Morgan; Brave New Climate; 16 Jan 2013

Discusses US Navy and PARC processes for extracting CO
from seawater, and costings including nuclear costs

Hypothetical use of nuclear energy

Recycling CO₂ in U.S. Navy with SMR (Small Modular Reactors)] Don Larson; YouTube; 26 Apr 2015

Pulling carbon dioxide from seawater and recycling it into liquid fuel has been prototyped by U.S. Naval Research Laboratory. It needs to be scaled up, and provided with inexpensive energy to drive the process.

Hydrocarbon bonds in Camelina-derived JP-5 can be shaped so the fuel has higher energy density than petroleum-derived JP-5. NRL fuel has performance properties superior to fossil fuel sourced fuel.

SMR exist today in the Navy, on carriers and submarines. USS Enterprise had eight A2W reactors. They can be built, and expanded modularity. They do not require a site license.

FY 2013 procurement and delivery at sea was $6.60 per gallon. 540 million gallons for $3.6 BB. Current procurement presents logistic and on-station issues.

Don Larson gave this presentation for eGeneration at the 5th Annual Small Modular Reactor Conference, 2015 in North Carolina.

The Molten Salt Reactors Don Larson cites as capable of generating high temperatures capable of directly disassociating hydrogen from oxygen in water (bypassing electrolysis entirely) are being designed by Terrestrial Energy and Flibe Energy.

to alcohols

Atmospheric CO
to Methanol - University of Southern California, George Olah and Surya Prakash

Carbon dioxide-to-methanol catalyst ignites ‘fuel from air’ debate ANDY EXTANCE; Chemistry World; 14 JAN 2016

Chemists in the US have created a catalyst system that they say is the first to make methanol straight from the tiny concentration of carbon dioxide in Earth’s atmosphere.1 The approach developed by George Olah and Surya Prakash’s University of Southern California (USC) team uses milder conditions than existing carbon dioxide-to-methanol processes. It is an initial step towards realising the group’s vision of making fuel from nothing but gases from the air and renewable energy, Prakash tells Chemistry World. However, Harvard University’s David Keith, a leading expert on ‘air capture’ of carbon dioxide from the atmosphere, is sceptical the new process can deliver on that promise.

to alcohol "bionic leaf" - Harvard Uni + Medical School, Daniel Nocera, Pamela Silver et al

New “Bionic” Leaf Is Roughly 10 Times More Efficient Than Natural Photosynthesis David Biello; Scientific American; 1 Aug 2016

PV powers electrolysis of H
O, microbes use H
to convert CO
to alcohol

It converts CO
in the air into alcohol that can be burned as fuel

Chemist Daniel Nocera of Harvard University and his team joined forces with synthetic biologist Pamela Silver of Harvard Medical School and her team to craft a kind of living battery, which they call a bionic leaf for its melding of biology and technology. The device uses solar electricity from a photovoltaic panel to power the chemistry that splits water into oxygen and hydrogen. Microbes within the system then feed on the hydrogen and convert carbon dioxide in the air into alcohol that can be burned as fuel. The team's first artificial photosynthesis device appeared in 2015—pumping out 216 milligrams of alcohol fuel per liter of water—but the nickel-molybdenum-zinc catalyst that made its water-splitting chemistry possible had the unfortunate side effect of poisoning the microbes. So the team set out in search of a better catalyst and, as recently reported in Science, the researchers found it in an alloy of cobalt and phosphorus, an amalgam already in use as an anticorrosion coating for plastic and metal parts. With this new catalyst in the bionic leaf, the team boosted version 2.0's efficiency at producing alcohol fuels such as isopropanol and isobutanol to roughly 10 percent. In other words, for every kilowatt-hour of electricity, the microbes could scrub 130 grams of CO
out of the air to make 60 grams of isopropanol fuel. Such a conversion is roughly 10 times more efficient than natural photosynthesis.

Gaseous CO
to Ethanol - Oak Ridge

High-Selectivity Electrochemical Conversion of CO
to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode
Dr. Yang Song, Dr. Rui Peng, Dale K. Hensley, Dr. Peter V. Bonnesen, Dr. Liangbo Liang, Dr. Zili Wu, Dr. Harry M. Meyer III, Dr. Miaofang Chi, Dr. Cheng Ma, Dr. Bobby G. Sumpter, Dr. Adam J. Rondinone; Chemistry Select; 28 Sep 2016

Though carbon dioxide is a waste product of combustion, it can also be a potential feedstock for the production of fine and commodity organic chemicals provided that an efficient means to convert it to useful organic synthons can be developed. Herein we report a common element, nanostructured catalyst for the direct electrochemical conversion of CO
to ethanol with high Faradaic efficiency (63 % at −1.2 V vs RHE) and high selectivity (84 %) that operates in water and at ambient temperature and pressure. Lacking noble metals or other rare or expensive materials, the catalyst is comprised of Cu nanoparticles on a highly textured, N-doped carbon nanospike film. Electrochemical analysis and density functional theory (DFT) calculations suggest a preliminary mechanism in which active sites on the Cu nanoparticles and the carbon nanospikes work in tandem to control the electrochemical reduction of carbon monoxide dimer to alcohol.

Nano-spike catalysts convert carbon dioxide directly into ethanol Morgan McCorkle; Oak Ridge National Laboratory; 12 Oct 2016

scientists at the Department of Energy’s Oak Ridge National Laboratory have developed an electrochemical process that uses tiny spikes of carbon and copper to turn carbon dioxide, a greenhouse gas, into ethanol. Their finding, which involves nanofabrication and catalysis science, was serendipitous. “We discovered somewhat by accident that this material worked,” said ORNL’s Adam Rondinone, lead author of the team’s study published in ChemistrySelect. “We were trying to study the first step of a proposed reaction when we realized that the catalyst was doing the entire reaction on its own.” The team used a catalyst made of carbon, copper and nitrogen and applied voltage to trigger a complicated chemical reaction that essentially reverses the combustion process. With the help of the nanotechnology-based catalyst which contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 percent. Typically, this type of electrochemical reaction results in a mix of several different products in small amounts. “We’re taking carbon dioxide, a waste product of combustion, and we’re pushing that combustion reaction backwards with very high selectivity to a useful fuel,” Rondinone said. “Ethanol was a surprise -- it’s extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst.” The catalyst’s novelty lies in its nanoscale structure, consisting of copper nanoparticles embedded in carbon spikes. This nano-texturing approach avoids the use of expensive or rare metals such as platinum that limit the economic viability of many catalysts. ORNL researchers developed a catalyst made of copper nanoparticles (seen as spheres) embedded in carbon nanospikes that can convert carbon dioxide into ethanol. “By using common materials, but arranging them with nanotechnology, we figured out how to limit the side reactions and end up with the one thing that we want,” Rondinone said. The researchers’ initial analysis suggests that the spiky textured surface of the catalysts provides ample reactive sites to facilitate the carbon dioxide-to-ethanol conversion. “They are like 50-nanometer lightning rods that concentrate electrochemical reactivity at the tip of the spike,” Rondinone said. Given the technique’s reliance on low-cost materials and an ability to operate at room temperature in water, the researchers believe the approach could be scaled up for industrially relevant applications. For instance, the process could be used to store excess electricity generated from variable power sources such as wind and solar.

Also at

Scientists Accidentally Discover Efficient Process to Turn CO
Into Ethanol
Avery Thompson; Popular Mechanics; 17 Oct 2016

Scientists at the Oak Ridge National Laboratory in Tennessee have discovered a chemical reaction to turn CO
into ethanol, potentially creating a new technology to help avert climate change. Their findings were published in the journal ChemistrySelect. The process is cheap, efficient, and scalable, meaning it could soon be used to remove large amounts of CO
from the atmosphere. The tech involves a new combination of copper and carbon arranged into nanospikes on a silicon surface. The nanotechnology allows the reactions to be very precise, with very few contaminants.

Gaseous CO
to Methanol - Air Fuel Synthesis, UK

The big question mark over gasoline from air Paul Marks; New Scientist; 22 Oct 2012

In a shipping container on a British industrial park, not far from where George Stephenson launched the world’s first steam railway in 1825, another transport revolution might be beginning. Every day the machinery inside produces half a litre of purified gasoline. It sounds humdrum until you realise one thing: the only raw material used is air.

Last week, Air Fuel Synthesis (AFS), a company in Stockton, UK, revealed the first successful demonstration of an idea that dates back to the oil crisis of the 1970s: that carbon, hydrogen and oxygen can be plucked from carbon dioxide and water in air to be converted into methanol and then morphed into gasoline.

However, amidst the headlines, some media coverage overlooked the key point: the energy efficiency of the process has yet to be demonstrated. This matters because the technique uses electricity for key stages. The inventors hope to use renewable energy sources to supply this, but it’s not yet clear if the system will be able to produce fuel at an affordable price.

Domain name currently for sale

to Methane

One issue with producing synthetic methane (also known as Renewable Natural Gas - RNG) either by synthesis from CO
or from waste (e.g. by anaerobic digestion - AD) is the global heating effect of the methane that inevitably leaks from such systems. Since methane is a very powerful greenhouse gas it is challenging to make these systems completely climate neutral, rather than simply less bad than using fossil gas.

Emily Grubert discussed the issues on Twitter ahead of peer review and formal publication of her paper "At scale, renewable natural gas systems could be climate intensive: The influence of methane feedstock and leakage rates" in IOP Science on 14 May 2020


Renewable natural gas (RNG) is a fuel comprised of essentially pure methane, usually derived from climate-neutral (e.g., biogenic or captured) carbon dioxide (CO
). RNG is proposed as a climate friendly direct substitute for fossil natural gas (FNG), with the goal of enabling diverse natural gas users to continue operating without substantial infrastructure overhauls. The assumption that such substitution is climate friendly relies on a major condition that is unlikely to be met: namely, that RNG is manufactured from waste methane that would otherwise have been emitted to the atmosphere. In practice, capturable waste methane is extremely limited and is more likely to be diverted from a flare than from direct atmospheric release in a climate-conscious policy context, which means that RNG systems need to be more destructively efficient than a flare to provide climate benefits versus the likely alternative management strategy. Assuming demand levels consistent with the goal of using existing FNG infrastructure, RNG is likely to be derived from methane that is either intentionally produced or diverted from a flare, so essentially any methane leakage is climate additional. Further, in a decarbonizing system, RNG will likely compete with lower-emissions resources than FNG and thus provides fewer net emissions benefits over time. Anticipated leakage is climatically significant: literature estimates for methane leakage from biogas production and upgrading facilities suggest that leakage is in the 2-4% range (mass basis), up to as much as 15%. Policy makers should consider that under reasonable leakage and demand assumptions, RNG could be climate intensive.

Coal to Liquid fuels

Proposal to use cheap nuclear power to drive coal liquefaction to provide liquid chemical fuels


Synthetic, affordable coal-based fuels could revolutionize the US economy. By harnessing next generation fission technologies, the costs of producing clean coal-based fuels would drop dramatically.

Syngas to liquid fuels

Integrated bioprocess for conversion of gaseous substrates to liquids Peng Hua, Sagar Chakrabortya, Amit Kumara, Benjamin Woolstona, Hongjuan Liua, David Emersona, Gregory Stephanopoulos; PNAS; 13 Jan 2016

In the quest for inexpensive feedstocks for the cost-effective production of liquid fuels, we have examined gaseous substrates that could be made available at low cost and sufficiently large scale for industrial fuel production. Here we introduce a new bioconversion scheme that effectively converts syngas, generated from gasification of coal, natural gas, or biomass, into lipids that can be used for biodiesel production. We present an integrated conversion method comprising a two-stage system. In the first stage, an anaerobic bioreactor converts mixtures of gases of CO
and CO or H
to acetic acid, using the anaerobic acetogen Moorella thermoacetica. The acetic acid product is fed as a substrate to a second bioreactor, where it is converted aerobically into lipids by an engineered oleaginous yeast, Yarrowia lipolytica. We first describe the process carried out in each reactor and then present an integrated system that produces microbial oil, using synthesis gas as input. The integrated continuous bench-scale reactor system produced 18 g/L of C16-C18 triacylglycerides directly from synthesis gas, with an overall productivity of 0.19 g⋅L−1⋅h−1 and a lipid content of 36%. Although suboptimal relative to the performance of the individual reactor components, the presented integrated system demonstrates the feasibility of substantial net fixation of carbon dioxide and conversion of gaseous feedstocks to lipids for biodiesel production. The system can be further optimized to approach the performance of its individual units so that it can be used for the economical conversion of waste gases from steel mills to valuable liquid fuels for transportation.

MIT researchers turn waste gas into liquid fuel

The Massachusetts Institute of Technology (MIT) process uses bacteria to convert the waste gases into acetic acid - vinegar - then an engineered yeast to produce an oil.

Plastic waste to liquid fuels

Chemists find new way to recycle plastic waste into fuel University of California, Irvine News; 21 Jun 2016

A new way of recycling millions of tons of plastic garbage into liquid fuel has been devised by researchers from the University of California, Irvine and the Shanghai Institute of Organic Chemistry (SIOC) in China.