## US Navy demos recovery of CO2 and production of H2 from seawater, with conversion to liquid fuel; “Fuel from Seawater”

##### 08 April 2014

Researchers at the US Naval Research Laboratory (NRL), Materials Science and Technology Division have demonstrated novel NRL technologies developed for the recovery of CO2 and hydrogen from seawater and their subsequent conversion to liquid fuels. Flying a radio-controlled replica of the historic WWII P-51 Mustang red-tail aircraft (of the legendary Tuskegee Airmen), NRL researchers Dr. Jeffrey Baldwin, Dr. Dennis Hardy, Dr. Heather Willauer, and Dr. David Drab used a novel liquid hydrocarbon fuel to power the aircraft’s unmodified two-stroke internal combustion engine.

The test provides a proof-of-concept for an NRL-developed process to extract CO2 and produce hydrogen gas from seawater, subsequently catalytically converting the CO2 and H2 into fuel by a gas-to-liquids process. The potential longer term payoff for the Navy is the ability to produce fuel at or near the point of use when it is needed, thereby reducing the logistics tail on fuel delivery, enhancing combat capabilities, and providing greater energy security by fixing fuel cost and its availability.

From an environmental perspective, such a combination of integrated NRL-developed technologies could be considered CO2 neutral. The carbon dioxide, produced from combustion of the synthetic fuel, is returned to the atmosphere where it re-equilibrates with the ocean to complete the natural carbon cycle.

Using an innovative and proprietary NRL electrolytic cation exchange module (E-CEM), both dissolved and bound CO2 are removed from seawater at 92% efficiency by re-equilibrating carbonate and bicarbonate to CO2 and simultaneously producing H2. The gases are then converted to liquid hydrocarbons by a metal catalyst in a reactor system.

The energy required to obtain these feedstocks from the ocean is primarily for the production of hydrogen; the carbon dioxide is a “free” byproduct. The process of both recovering CO2 and concurrently producing H2 gas eliminates the need for additional large and expensive electrolysis units.

In close collaboration with the Office of Naval Research P38 Naval Reserve program, NRL has developed a game-changing technology for extracting, simultaneously, CO2 and H2 from seawater. This is the first time technology of this nature has been demonstrated with the potential for transition, from the laboratory, to full-scale commercial implementation.

—Dr. Heather Willauer, NRL research chemist

CO2 in the air and in seawater is an abundant carbon resource, but the concentration in the ocean (100 milligrams per liter [mg/L]) is about 140 times greater than that in air, and 1/3 the concentration of CO2 from a stack gas (296 mg/L). Two to three percent of the CO2 in seawater is dissolved CO2 gas in the form of carbonic acid, one percent is carbonate, and the remaining 96 to 97% is bound in bicarbonate.

NRL has made significant advances in the development of a gas-to-liquids (GTL) synthesis process to convert CO2 and H2 from seawater to a fuel-like fraction of C9-C16 molecules.

In the first patented step, an iron-based catalyst has been developed that can achieve CO2 conversion levels up to 60% and decrease unwanted methane production in favor of longer-chain unsaturated hydrocarbons (olefins). These value-added hydrocarbons from this process serve as building blocks for the production of industrial chemicals and designer fuels.

 E-CEM Carbon Capture Skid. The E-CEM was mounted onto a portable skid along with a reverse osmosis unit, power supply, pump, proprietary carbon dioxide recovery system, and hydrogen stripper to form a carbon capture system [dimensions of 63" x 36" x 60"]. (Photo: US Naval Research Laboratory) Click to enlarge.

In the second step, using a solid acid catalyst reaction, these olefins can be oligomerized (a chemical process that converts monomers, molecules of low molecular weight, compounds of higher molecular weight using controlled polymerization). The resulting liquid contains hydrocarbon molecules in the carbon rang—C9-C16—suitable for use a possible renewable replacement for petroleum-based jet fuel.

The predicted cost of jet fuel using these technologies is in the range of $3-$6 per gallon, and with sufficient funding and partnerships, this approach could be commercially viable within the next seven to ten years, the Navy researchers suggested. Pursuing remote land-based options would be the first step towards a future sea-based solution.

The minimum modular carbon capture and fuel synthesis unit is envisioned to be scaled-up by the addition individual E-CEM modules and reactor tubes to meet fuel demands.

NRL operates a lab-scale fixed-bed catalytic reactor system and the outputs of this prototype unit have confirmed the presence of the required C9-C16 molecules in the liquid. This lab-scale system is the first step towards transitioning the NRL technology into commercial modular reactor units that may be scaled-up by increasing the length and number of reactors.

The process efficiencies and the capability to simultaneously produce large quantities of H2, and process the seawater without the need for additional chemicals or pollutants, has made these technologies far superior to previously developed and tested membrane and ion exchange technologies for recovery of CO2 from seawater or air, according to the team.

$3-$6/gallon production cost presumably assumes that the input energy is free.  This is effectively true on a nuclear aircraft carrier (which is rarely steaming at full speed and can put excess power to other purposes), but questionable elsewhere.

Exactly. Energy balance is shown in the paper here:

Even then the machinery to produce the fuel would not be trivial. Believe it or don't, even on the mighty Vinson, packaging this fuel factory is no mean feat.

Electrofuels are at a very early stage. If it can be done @ $6.00/gallon now it is a great success. It could become a way to make intermittent (Solar, Wind etc) energy sources 24/7. This is the Navy at work, creating another incredibly expensive target for relatively cheap missiles to destroy. Many thanks for the link Herman. The calculations seem highly speculative to me. The report is full of phrases like: 'the theoretical amount of seawater needed is....' OTEC as a power source is wholly speculative, and the costings at this stage of the development of the technology are no more than WAGS. On page 9 they give the capital cost of Navy nuclear power at$1,200kw!
At that rate then never mind jet fuel, simply build barges, install Navy nuclear reactors on them and sell the power to the grid!

Either that is a massive underestimate, as it is way, way below the cost of civil nuclear power in the US, or the Navy can produce nuclear reactors at a fraction of the civil cost, even less than the Chinese, presumably due to not having to comply with civil nuclear regulation and regulatory delays etc.

Does the Navy really build reactors so cheaply?

@Engineer-Poet, this is true but $3-6/gal is nearly an order of magnitude cheaper than current fuel costs. Further, being able to produce your own fuel at multiple mobile forward points of operations has tremendous value. This seems like a no-brainer decision to me for the military... which is why they'll probably drag their heels, lol. @Davemart: I have a friend at Burns and Roe who has told me that the USN's capital costs for nuclear power are in the$1,000-1,500/kw range so that certainly doesn't seem out of line. No interest payments to make and no regulatory bodies to stop them.

At those costs, wire them up to the grid in floating barges and low carbon energy is solved.

Are you aware of the fortune we paid to ship Persian Gulf petroleum products to Afghanistan, thanks largely to the mafia-like bottleneck of Pakistan? And the runup in gasoline prices this caused? How Iraqi petroleum failed to come online to sustain Operation Desert Freedom, and the continued dependence we had on Gulf petroleum? On the other hand, our nuclear carriers are remarkably long-lived and now at least can deliver an ancillary return on capital (aviation fuel) which nuclear warheads cannot, unless you count the loss-inducing reprocessing of HEU and plutonium.

I'd say the mere act of determination in war counts as much as warmaking itself. Even Sheik Yahmani of OPEC quaked that alternative energy would put Big Oil out of business. Far from true, but it did put the fear of Allah in certain adversaries.

On page 9 they give the capital cost of Navy nuclear power at $1,200kw! ... Either that is a massive underestimate, as it is way, way below the cost of civil nuclear power in the US, or the Navy can produce nuclear reactors at a fraction of the civil cost, even less than the Chinese Naval reactors are small, modular, and built on an assembly line. They are built in a factory rather than on-site, and they've got quite a bit of experience with turning them out consistently and on schedule. Plus, there are no lawyers involved. This resembles the state of affairs under the AEC rules, when nuclear plants were actually cheaper to build than coal and were expected to completely replace coal by the turn of the 21st century. There are any number of nuclear technologies designed to be factory-built in modular units and delivered intact to the installation site (mPower, Hyperion, NuScale) and achieve similar economies. Our need for carbon-free power could support many times the production rate of naval reactors. It's ironic that the biggest fear of the Greens isn't that nuclear power cannot replace fossil fuels and provide prosperity AND clean energy, but that it WILL. @E-P, I had no doubt that SMR can be cost effective and safe, and would be ideal as baseload electricity provider for the grid to replace coal. However, despite the cost-effectiveness and relative safety of SMR as demonstrated in the USN fleet, no commercial shipping vessel has adopted this energy source for propulsion, due to liability risk? or due to anti-nuclear-prohibiting regulations? Perhaps with modern computers, advanced sensors and monitoring system and networking, and better fail-safe design, these type of SMR will be able to replace all coal-fired power plants in existence with the same safety records and cost-effectiveness as the USN nuclear powered fleet. @Roger Pham I believe the reason nuclear cargo vessels have not been adopted is because, at this time, any build would be a one-off and the refueling facilities and staff would be specialized/one-offs. As such, there is disadvantage to being a first mover. IMO, SMRs could work now but utilities are capital constrained as they have milked their equity to pay shareholders and pensioners. GreenPlease, The companies who are building Navy SMR can also supply the commercial shipping fleet using already proven design(s), or to re-power existing coal-fired power plants, if such a market exists. Those ex-Navy-trained nuclear engineer /technicians can find a second career aboard commercial vessels or to work in re-powered existing coal-fired plants, if such a job exist. Let's not forget that the$1,250/kW for a Navy SMR does not include the much larger decommissioning costs later at the end of the life of the reactor, perhaps many folds higher per kW, because almost everything in it is radioactive and must be disposed of properly to keep the workers and the environment safe...including the nuclear waste. It takes a loooong time to decommission a nuclear power plant!
On the contrary, solar and wind energy collectors contain no radioactivity and the materials can be recycled upon decommissioning, thus negating any associated tear-down costs.

Rod Adams says that the Navy keeps its nuclear expertise under lock and key.  Naval propulsion reactors are not for sale to the public; Adams himself advanced a very different nuclear technology for ship propulsion.

The actual cost of Naval Nuclear Propulsion is not easily compared to that of equipment used for utility power.

First of all, when the Navy expresses reactor output, they do so in terms of Mw(thermal). With only a couple of exceptions (the Tullibee and Lipscomb are the only ones I know), most of the energy produced by a naval reactor is used to drive steam turbines that connect mechanically to the propulsion shaft(s). Therefore, the 220Mw output of the S6W submarine reactor refers to the gross thermal energy output -- to translate that to a typical land-based reactor electrical output you would multiply by 0.3 or so. So the $1200/kw in this conversation goes to about$3500/kw on an apples-to-apples basis.

Moreover, I'm almost certain the $x/kw "capital cost" does not include the core itself. I'd bet my next quarter's billings that is separately costed as an element of the DoE budget authority. Naval reactor cores are wildly different from their civilian counterparts, with fuel configured not in separate rods but in a single unified structure of plates in a quite unique arrangement. Enrichment is stunningly high: over 90% compared to 2-3% in a civilian core. No, they cannot become "bombs" because of dispersion and configuration of fuel and cladding, but they are far more expensive than the already eye-wateringly high cost of civilian fuel. But the biggest reason you will not see a US Navy unit in ANY civilian application is the very different approach to operation and safety. Navy reactors have very few automated shutdown protections. Instead they are dependent on (1) an extremely robust negative temperature coefficient of reactivity throughout the range of power output in all phases of core life, (2) an inviolable and conservative safe operating envelope with significant structural and thermal margins, (3) zero tolerance for fission product daughters in the primary coolant loop under ANY conditions, and (4) a very highly trained operating team. They do not possess the exceptional strength of containment we expect from utility reactors (owing quite obviously to mass and volumetric limitations of the warship itself). They must also be able to very quickly recover from inadvertent shutdowns in order to maintain vessel propulsion in combat conditions (translation: fast recovery startup rates that would make a utility operator soil his trousers). THIS IS NOT TO SAY THEY ARE "UNSAFE" IN ANY WAY, but they simply are not the same thing as, say, an AP1000. Finally, as many mentioned here, the overall lifetime support (including essentially limitless years of safe storage of decommissioned waste materials) is in no way included in the "sticker price". A while back I heard of a SMR design that wouldn't have any decommissioning costs at end of the life, nor any need for "ex-Navy-trained nuclear engineer/technicians" to operate it. The idea was to just bury the reactor a thousand feet underground and it would run without tending because it was designed with passive controls, and it would have no decommissioning costs because once its fuel was used up you would just cut the output cable, leave the reactor in place and dig a new hole for a fresh SMR. The Hyperion E-P mentioned fits that description; http://phys.org/news145561984.html but I sure there must be others. I do admit to proposing that we site reactors in mines below cities, to achieve further defense in depth against radioisotope releases while making it feasible to use spent steam for space heating. Decommissioning such reactors would probably require removal of the fuel (residual heat output would otherwise be a problem) and would certainly require sealing coolant passages going to it. Other than that, entombing the empty reactor in concrete should pretty much do it. What appeals to me about SMRs is that they are small. The utilities are talking about facing a death spiral and building big power plants of any kind just runs the risk of emplacing another future stranded asset. Better to build lots of small power: Small, fast, flexible, distributed, and smart. Thanks, ai vin for the info. Also, the Hyperion reactor is about the size of the reactor in the Los Angeles-class of Navy nuclear-powered destroyer. A few of these could power a container cargo ship for 7-10 years at a time without refueling. Container ship needs steady power on 24-7 basis, so this would be ideal. While at port, the electricity power from the ship's nuclear plant can be plugged into the local gird to power the local grid in order for not having to throttle down the reactor. One issue of concern for nuclear powered container ships could be piracy. Seaborne piracy against transport vessels remains a significant issue (with estimated worldwide losses of US$13 to \$16 billion per year), particularly in the waters between the Red Sea and Indian Ocean, off the Somali coast, and also in the Strait of Malacca and Singapore, which are used by over 50,000 commercial ships a year. In recent years, shipping companies claimed that their vessels suffer from regular pirate attacks on the Serbian and Romanian stretches of the international Danube river, i.e. inside the European Union's territory, starting from at least 2011.

Modern pirates favor small boats and taking advantage of the small number of crew members on modern cargo vessels. They also use large vessels to supply the smaller attack/boarding vessels. Modern pirates can be successful because a large amount of international commerce occurs via shipping. Major shipping routes take cargo ships through narrow bodies of water such as the Gulf of Aden and the Strait of Malacca making them vulnerable to be overtaken and boarded by small motorboats. Other active areas include the South China Sea and the Niger Delta. As usage increases, many of these ships have to lower cruising speeds to allow for navigation and traffic control, making them prime targets for piracy.

A nuclear-powered cargo vessel would have no reason to operate at less than full speed/power in open seas; saving fuel would not be a consideration.  Given the superior speed, pirate-ridden bottlenecks like the Strait of Malacca could simply be bypassed.  The ship might even be able to make better time overall.

Roger: not to be picky but the Los Angeles class are Fast Attack Submarines (SSN-688 lead vessel), not destroyers.

E-P, this is true, and many ships do take the longer but safer route around the Cape of Good Hope. But hull speed is still hull speed so I wouldn't expect these ships to automatically make better time just because they are nukes.

However, given that only ~8 % of the world seaborne trade passes through the Suez Canal, it would be worthwhile to see which routes could be changed. The routes that save the most time by going through the canal start at either Ras Tanura or Jeddah, both are major oil ports. But of course we want to stop using oil so maybe we could cut that traffic altogether. ;)

http://www.suezcanal.gov.eg/sc.aspx?show=11

@Herman:
Many thanks for the very knowledgeable insights.

Al:
With no worries about fuel consumption in nuclear vessels, ships, even massive container ships I would imagine providing the materials strengths are up to it, could simply plane.
No pirate is going to catch a ship moving at 35 knots or so!
If that it practical, they would be a heck of a sight at sea whizzing along! :-)

Davemart: The simplest way of increasing the speed of a container ship is to just make it longer. As a bonus it could carry more cargo. If built to the "New Panamax" standard such a ship could be 1200 ft long and travel at 47 knots. However most ships travel at nowhere near their top speed in open waters for reasons other than fuel use. The violent slamming motion of a ship in a rough seaway is a major reducer of speed.

The comments to this entry are closed.