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PNNL solar thermochemical reaction system can reduce fuel consumption in natural gas power plants by about 20%; future potential for transportation fuels

PNNL’s thermochemical conversion device is installed in front of a concentrating solar power dish. Photo: PNNL. Click to enlarge.

A new concentrating solar power system developed by Pacific Northwest National Laboratory (PNNL) can reduce the fuel consumption of a modified natural-gas combined-cycle (NGCC) power plant by about 20%. The system converts natural gas into syngas—with higher energy content than natural gas—using a thermochemical conversion device installed in front of a concentrating solar power dish. The power plant then combusts the more energy dense syngas to produce electricity.

PNNL’s system uses a mirrored parabolic dish to direct sunbeams to a central point, where the thermochemical device uses the solar heat to produce syngas form natural gas. About four feet long and two feet wide, the device contains a chemical reactor and several heat exchangers. Concentrated sunlight heats up the natural gas flowing through the reactor’s channels, which hold a catalyst that helps turn natural gas into syngas.

The full CSP system. Photo: PNNL. Click to enlarge.

The heat exchanger features microchannels that are a couple times thicker than a strand of human hair. The exchanger’s channels help recycle heat left over from the chemical reaction gas. By reusing the heat, solar energy is used more efficiently to convert natural gas into syngas. Tests on an earlier prototype of the device showed more than 60% of the solar energy that hit the system’s mirrored dish was converted into chemical energy contained in the syngas.

PNNL is refining the earlier prototype to increase its efficiency while creating a design that can be made at a reasonable price. The project includes developing cost-effective manufacturing techniques that could be used for the mass production. The manufacturing methods will be developed by PNNL staff at the Microproducts Breakthrough Institute, a research and development facility in Corvallis, Ore., that is jointly managed by PNNL and Oregon State University.

Our system will enable power plants to use less natural gas to produce the same amount of electricity they already make. At the same time, the system lowers a power plant’s greenhouse gas emissions at a cost that’s competitive with traditional fossil fuel power.

—PNNL engineer Bob Wegeng, project leader

PNNL will conduct field tests of the system at its campus in Richland, Wash., this summer.

The US Energy Information Administration estimates natural gas will make up 27% of the nation’s electricity by 2020.

Wegeng noted PNNL’s system is best suited for power plants located in sunshine-drenched areas such as the American Southwest.

Wegeng’s team aims to keep the system’s overall cost low enough so that the electricity produced by a natural gas power plant equipped with the system would cost no more than 6 cents per kilowatt-hour by 2020. Such a price tag would make hybrid solar-gas power plants competitive with conventional, fossil fuel-burning power plants while also reducing greenhouse gas emissions.

The system is adaptable to a large range of natural gas power plant sizes. The number of PNNL devices needed depends on a particular power plant’s size. For example, a 500 MW plant would need roughly 3,000 dishes equipped with PNNL’s device.

PNNL’s system doesn’t require power plants to cease operations when the sun sets or clouds cover the sky. Power plants can bypass the system and burn natural gas directly.

Though outside the scope of the current project, Wegeng also envisions a day when PNNL’s solar-driven system could be used to create transportation fuels. Syngas can also be used to make synthetic crude oil, which can be refined into diesel and gasoline.

The current project is receiving about $4.3 million combined from DOE’s SunShot Initiative, which aims to advance American-made solar technologies, and industrial partner SolarThermoChemical LLC of Santa Maria, Calif.

SolarThermoChemical has a Cooperative Research and Development Agreement for the project and plans to manufacture and sell the system after the project ends.




That's brilliant, that would bring natural gas to probably 1/4 carbon footprint of coal for the same amount of electricity produced.


They could turn the syngas into DME and then into synthetic fuels as well. Low sulfur and no imported oil...most excellent :)

Kit P

"That's brilliant,"

The only thing brilliant at PNNL is the ability to suck money out of DOE.

"a 500 MW plant would need roughly 3,000 dishes equipped with PNNL’s device. "

A brilliant plan to make electricity with natural gas more expensive.


That is a lot of dishes in the present design but the payback is not bad. They save 20% in fuel cost, even with only 2000 hours per year of sun they can save $10 million per year. If they can keep the cost per dish under $10,000 they have a 5 year payback.


What they're doing is steam reforming of methane, using solar heat to supply the reaction enthalpy for the endothermic reforming reaction. Makes sense. In conventional steam reforming, the enthalpy is supplied by partial combustion, which reduces the yield of synthesis gas.

If they can manage the SMR reaction in a small reactor at the focus of a solar dish, they should also be able to take it to the next level. By capturing some of the CO2 from the turbine exhaust and feeding it back to the the input stream, it's possible to further enhance the yield of synthesis gas. Some of the hydrogen produced by the SMR reaction combines with CO2 in the reverse water gas shift reaction, giving CO and water vapor. With the combined SMR and RWGSR, could be boosted by 50%, rather than 20%.

By storing some of the synthesis gas produced during the day for burning at night, what you've achieved is the holy grail of renewable energy: economical stored solar energy.

A Facebook User

Not really sure as to what to make out of it.... US Government is anyways flushing a lot of cash down the drain one more crazy idea should not make any difference to the hard working taxpayers.

And if they keep throwing random darts into space.... one or more might actually hit a non existent target...


The figure of interest is not the 60% solar to chemical but 60x55 = 33% solar to electrical. Wikipedia says solar thermal can get to 31% and photovoltaic over 40% (all lab research figures so comparing like with like). Being able to store the solar is good but then you can and will cycle the CCGT so what have you really gained?

The energy is increased but so are the number of molecules, increasing the volume and decreasing the energy density? My real question is does this affect the power rating of the power station, ie is a power station rated at 500MW for methane also rated at 500MW for syn gas?



You summed it up correctly. I have thought that making power plants into energy plants that make fuel and electricity is the way to go.


The problem is that 80% of the energy still comes from fossil fuel.

There are a couple of ways to make this system better.  One is to react the syngas back to methane and steam in a heat exchanger which pre-heats the gas turbine combustion air.  The other is to pre-heat the air directly, using e.g. a solar power tower.  This not only displaces carbon fuel, it increases the ratio of specific heats of the combustion products (less fuel burned to reach rated turbine inlet temp) which means the gases cool more during expansion, yielding more of their energy as work.

Roger Pham

Good point, E-P.
The European are working a hybrid solar Brayton-cycle turbine using concentrated solar heat to heat the compressed air to 800 degrees C, and then use the NG to heat the air to 1200 degrees C, thus using as much as 50% solar heat. If turbine inlet temp is lowered to 1000 C, then 75% of solar energy can be used. Perhaps they can combine this idea to make syngas, and then use the syngas to only top off the final heating stage of the compressed air, then perhaps >80% of the energy can come from solar heat.

Roger Pham

Good point, Silverthorn, and welcome back after a long hiatus!
Economical storage of RE is always welcome.

Kit P

“The only way to permanently destroy these fissile materials is to burn them up in specialized nuclear furnaces. ”

“Good point, Silverthorn, and welcome back after a long hiatus!
Economical storage of RE is always welcome. ”

Got to love the progression of fantasies for something that is never going to happen. If PNNL ever did anything the practical, they did not issue a pressure release.

“campus in Richland ”

PNNL does not have a campus they have a bunch of office building. The every day boring jobs that produce power and nuclear fuel were called production facilities. I am not saying there are not a bunch of smart people there. If we still needed to make nuclear weapons better than those mean old commies in the USSR, then PNNL would serve a purpose.

The problem at PNNL is not the first person there with a PHD has ever produced power. If this solar device actually worked and not actually a violation of the second law of thermodynamics; then no one is going to put 3000 very expensive devices around a gas fired power plant that is intended to run a few months in the summer and winter.

For the same reason, we do not build nuke plants to run 50% of the time. While the government does not demand that our money be spent wisely, customers who buy power demand that we do it economically.

Roger Pham

Hey thanks, KP, for the continued pessimism, which does serve a good purpose of allowing us to focus deeper into the subject matter.

>>>If this solar device actually worked and not actually a violation of the second law of thermodynamics; then no one is going to put 3000 very expensive devices around a gas fired power plant that is intended to run a few months in the summer and winter.

Well, actually, the solar output can be stored, like Silverthorn discovered. If 50% solar energy can be used to make the CO like he has suggested, and this can be stored for extended periods of time, then the solar output of fall and spring can be used to make CO to be used in the summer and winter in order to greatly reduce the NG to consumption by 50%. The great thing about this is that the CO can be stored much easier than H2, due to no problem with Hydrogen embrittlement and hydrogen leakage problem. What is there not to like about this? No more intermittency problem associated with solar energy with this device! No more problem of making and storing H2 like many here have suggested.

Furthermore, this same solar device can be used to make hydrocarbon from synfuel, another way to store solar energy!
Or, solar PV's from rooftops can be used to make H2, then the H2 will be incorporated into the carbon from waste biomass and make hydrocarbon fuels for later use in existing infrastructure, using solar thermal heat at >70% efficiency to greatly boost the efficiency of the process. What is there not to like about this concept?

Kit P

“for the continued pessimism ”

On the contrary, I think that the US power industry will have no problem supply the power needs of Americans with insignificant environmental impact forever and a day.

You do not hear me moaning about AGW, pollution, or resource depletion.

“What is there not to like about this concept? ”

It is science fiction. PNNL has a concept and until these scientists can show engineers like me that is practical, it does not matter because none will get built.

What Roger et al do is take a concept and let their imagination run wild producing science fiction

Ten miles north of the 'PNNL campus' is Columbia Generating Station pumping out about 1200 MWh of power every hour while releasing almost no ghg. If more power was needed, one of the partially built plants could be finished.

Roger Pham

>>>>"You do not hear me moaning about AGW, pollution, or resource depletion."

No one here is moaning about AGW, nor GW, nor pollution, nor resource depletion. However, it is our collective responsibility to the future generations to bring SUSTAINABILITY into every actions of our lives. Only one word that we all need to remember: "Sustainability."

>>>>"It is science fiction. PNNL has a concept and until these scientists can show engineers like me that is practical, it does not matter because none will get built."

Please kindly read each article carefully before posting comments. This article clearly states: "Tests on an earlier prototype of the device showed more than 60% of the solar energy that hit the system’s mirrored dish was converted into chemical energy contained in the syngas."
So, it's not science fiction. It's here and it's real! A prototype has been built and demonstrated 60% efficiency! What more can you ask for? AND they are trying to make it even more efficient and ways to mass produce it cheaply! I don't have to use any imagination on this thing, because a picture of the prototype is included in the article.

Roger Pham

One more positive note that I'd like to add about this solar device is that the 60% solar efficiency is really outstanding! If used in CCGT of 60% efficiency, then the final electricity efficiency could be ~36% efficiency! This, in comparison to solar PV currently capable of 15-20% efficiency, almost double! Thus, a solar farm using this device only needs 1/2 the active surface area for the same output, AND the solar output can be stored on a seasonal scale for little to no extra cost! What is there not to like about this revolutionary solar device?

Kit P

"So, it's not science fiction."

To repeat my self, PNNL concept is impractical.

Roger's concepts are science fiction.

Roger Pham

>>>>"To repeat my self, PNNL concept is impractical."
Why? Please kindly give us your engineering analysis and supporting data. We owe it to the visitors of GCC to provide supporting factual data or analyses to support our assertion.

50 years ago, the Internet and the PC's that we are using now to reach each other are science fiction. 25 years ago, the iPhone and iPad and WiFi and G4 network are science fiction, but Steve Jobs didn't think so!Now, a typical teenager can walk on a sidewalk, chew gum and using Facebook all at the same time!


This is not a stunning breakthrough but it is interesting. I have advocated CO2 reuse, taking CO2 sequestered from power plants and using it for synthetic fuels.

It turns out this is one of the major options our government is exploring, if it becomes widespread we could cut out CO2 emissions in HALF. But there are some that say half is not enough, so I guess we should all forget that.

Roger Pham

This may be a perfect 50%-solution half-way house to utilize existing electricity generation via CCGT in combination with solar energy directly coupled with means for storage of solar energy.

Of course, wind, solar PV, nuclear, etc will continue to provide the grid with zero-carbon electricity, to be supplemented with CCGT power plants at certain times to match supply with demand. This method by PNNL can make CCGT power plants 50% greener.

Kit P

“Why? ”

So you are asking me to explain why putting 3,000 dishes around a 500 MW fossil plant is impractical.

There are fundamental concepts that many here do not understand about producing power. You hear this all the time.

“Internet and the PC's ”

These are power consuming electronic devices. Consumer electronics are greatly enhanced by reducing power consumption.

However, the fundamentals of producing power have not changed. Wires and pipes have to be a certain size to carry the load.

“using Facebook ”

Assuming he did not die of exposure. There is a huge difference between need and want.

Producing power is very high capital cost so we make conservative choices to unsure that our customers 'needs' are met.

So what is practical?

Sixty years ago making power with coal was a very practical way to meet our customers needs. Still is very practical. The use of the heat form the sun was around but not very practical way to produce power on cold winter nights. Producing power with fission was not yet practical. A statement by one person about power to cheap to meter was an example of science fiction.

I like science fiction it is fun to think about.

Today, fission is a practical way to make power when a lot of power is needed as demonstrated by 20% share in the mix.

We have a long history of high temperature solar. None have been demonstrated the least bit practical and they all have a big natural gas pipe line.

“widespread we could cut out CO2 emissions in HALF ”

Or we could build zero emission nuke plants instead of 700 g/kwh gas plants.

“if it becomes ”

If this , if that, maybe, might, would of, could of, should of; none come place to actually doing it everyday.

So the answer to Roger's, the reason why is engineers make practical choices. This will never be one of them even if your goal is to reduce ghg. It is not up to me to demonstrate what is practical. PNNL will fail. They always do.


The DOE never seems to tire of throwing money at the problem of supply side management. At least here in Ontario we have put wind turbine installations on hold but you have to wonder how these projects get ramped up so rapidly. Oh right, lobbyists !

Meanwhile there seems to be precious little interest in promoting improvements that could be immediately beneficial on the demand side instead. Sure there is Time of Day metering with its punitive rates at peak periods, but no domestic electric water heater control that could allow power operators to remotely dump these significant low priority loads as peak periods are encountered.

Other low tech solutions bring into question the reason for the poor availablility of LED fixtures for residential housing.
It seems that unless you are prepared to use AA batts or wall sockets there seems to be a dearth of LED powered ceiling fixtures to be found in local stores.


I don't think the fossil fuel industry is looking for ways to increase their consumption of solar energy. Any kind of financial success for your competitors can lead to enhanced supplier deals, manufacturing and operational improvements, further financial support and potential break throughs from real operations lessons. Why would fossil energy want to encourage that for solar? Technically we can analyze costs and processes all we want but motivation is important too. I doubt Fossil energy is motivated to add to the customers of solar energy.


Oh right T2, it MUST be the lobbyists because lord knows the other side doesn't have lobbyists. And even if they did they couldn't possibly be better funded, what with the miniscule profits the fossil fuel industry makes. [sarcasm mode OFF]

Roger Pham

Good point, demand reduction cost less than building new zero-carbon electric generation. However, please realize that we are awashed with energy potential all around us. Wind energy potential is 40x the total electricity consumption. Solar energy's potential is probably 1000x our total energy consumption. Nature's energy is bountiful if we know how to harvest it. That's also the DOE's mission in sponsoring this PNNL project.

The biggest goal is not about saving money. It is about sustainability and it is also about creating jobs. Renewable Energy (RE) can do both. The Energy Companies' role is to bring energy to society while making their living. If RE will be cost-competitive with fossil fuels, or will be made that way if the external costs of fossil fuels will be taken in to account, then the Energy Companies will go the RE route. The DOE's role is also to ensure that RE will be competitive with fossil fuels.

Regarding "practical", what was practical in the past may not be practical in the future. Over a century ago, horse-drawn carriage was practical. Now, it is no longer practical. If you were to talk to a horsewhip maker or buggy maker back then, they will tell you that automobiles are not practical because they are very noisy and emit noxious fumes!

With on-going research and development in RE, RE will be the most practical in the near future. Advancements in nuclear energy also will make this more practical. The grid can support about up to 50% nuclear energy, mostly as baseload power. Fossil fuels will no longer be practical, for many obvious reasons.

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