Fossil Carbon Muddies The New Clean Fuels

Even if it gets its energy from the sun, the burgeoning sustainable fuels industry will only worsen climate change if it gets CO2 from the earth and not from the air, an expert on the carbon cycle said Tuesday.
Sustainable fuels are hydrocarbon alternatives to fossil petroleum that are made through photosynthesis—such as fuels made from algae or grasses—or thermochemical reactions. Potentially, they could emit only carbon that has been extracted from the atmosphere, providing a fuel with a closed carbon cycle for those industries, like air transport and heavy equipment, that may continue to need liquid fuels.
But that promise is squandered if sustainable fuels are made using fossil carbon, as some are currently, said Klaus Lackner, director of the Center for Negative Carbon Emissions and a professor of engineering at Arizona State University.
"It's a non-starter," Lackner said, "and in some ways it's detrimental because it entrenches a technology you really don't want to entrench."
Lackner stirred an otherwise staid discussion on carbon recycling Tuesday after Timothy Zenk, an executive vice president for Algenol, a Florida company, outlined his company's plan to buy CO2 that would otherwise be emitted from power plants and use it to grow algae that will be harvested for biofuel.
"In the business approach that we are taking, we actually want to purchase CO2 from our industrial large emitters," Zenk said during a webinar hosted by Arizona State University's LightWorks program in light-inspired research.
"We're actually paying $1 a ton for CO2 today. We have signed two long-term 24-year agreements to do that, so there is demand in the space for that new business model."
Algenol's fuel emits 69 percent less carbon than fossil fuels, Zenk said, and represents a more viable destination for carbon pollution than sequestration in the earth.
"Carbon capture sequestration really has a challenge because of the costs," Zenk said. "When you think of this in a portfolio approach, carbon capture and utilization may be the way of the future for the reduction of emissions."
But carbon sequestration, and nothing less than sequestration, is needed to counteract the release of fossil carbon, according to Lackner.
"While often it is stated that we have to reduce emissions, let me make one point very clear. If we want to stabilize the carbon dioxide in the atmosphere at some level—it really doesn't matter which level—you end up having to stop emissions virtually completely."
Even at one-third of current emissions, Lackner said, CO2 concentrations will continue to rise. Reducing emissions to 10 percent may pause the increase for a while, but it would eventually resume.
"Even if we stopped completely, it would take a very very long time to level things out," he said. "For all practical purposes, we have to stop emitting, and we have to do it relatively fast."
And not just stop emitting, Lackner added, but we will probably have to extract some of the carbon we have already emitted. To bring atmospheric concentrations to a safe level, he said, carbon that comes from the earth must be returned to the earth.
And all carbon emitted must be extracted:
" For every ton of carbon we put in the air, we have to take a ton back out. Even if that is made from synthetic fuels which are made without the help of fossil carbon, in the end if we put it in the air, we have to take it out."
Nonetheless, Zenk pointed out, the demand for hydrocarbon liquid fuels will not go away soon.
"The practical fact is that we're going to continue to use and burn hydrocarbons, and so the best way is to support the reduction of the intensity of carbon dioxide," he said, adding that Algenol would he happy to take carbon from the atmosphere, instead of the smokestack, if air capture were viable and affordable.
"We would be very satisfied in receiving that concentrated form of CO2 from air capture. It wouldn't eliminate our technology, it would actually uphold our ability to do what we want to do, which is to reduce emissions."
The debate then continued like this:
Lackner: Right, and I disagree with you on one point. If you had this as a bridging technology for a decade or two, I would say yes you are reducing CO2 emissions, but if your plan is to say for the next century we are going to see a lot of CO2 from fossil carbon sources like power plants, you cannot have that CO2 because you will ultimately put it into the air. So that CO2 must be stored because otherwise the power plant is not carbon neutral or you are not carbon neutral because you are burning fossil fuels.
Zenk: And I'm also displacing fossil fuels, and on a lifecycle basis the data is very clear, I reduce carbon emissions of fuels by 69 percent.
Lackner: I actually think this left out of the [calculation] the power plant itself.
Zenk: I'm not in the business of shutting down power plants of course, but there are a lot of technologies whether it be storage or other uses of carbon dioxide that are going to have to be part of a portfolio over the long haul in order to buy down the cost of storage.
Lackner: But you have to get rid of the fossil carbon…. If carbon came out of the ground, it has to go back into the ground, and you put it ultimately in the air. Yes, you help because you didn't use the petroleum you would have otherwise used, but the power plant made more CO2 than it made otherwise, and all of that CO2 ends up in the atmosphere.
Zenk: No disagreement, I'm just saying we are part of a portfolio, because my thesis is you're going to need dense hydrocarbon fuels for a very very very long time.
Lackner: Oh, that we agree on, but I'm saying you need to have the air capture source. Ultimately that CO2 you use has to come from the air in order to balance the books on the air.
Lackner sees a role for liquid fuels, he said, because he expects humans will have to reduce CO2 concentrations in the atmosphere by as much as 100 ppm—which will require the removal of about 1,500 gigatons.
Where to put all that CO2? It could be combined with hydrogen to make synthetic fuel, he said, and stored, serving as long-term backup power for renewables. Batteries can back up renewables in the short term—for hours or days—but stored fuel could back them up for weeks, months, seasons, or years.
Although CO2 would be released when the stored fuel is burned, the same CO2 would be removed again in a continuous cycle—as long as no fossil carbon is added to the mix.
Moderator Thomas Seager, an ASU professor who studies environmental decision making, tried to bridge the arguments by suggesting fossil CO2 could be used to foster carbon recycling fuel technologies until air capture becomes viable:
"As Klaus said, you're still putting it into the air, but changing the rate at which it enters the air, so ultimately to completely close the cycle I think we're all in agreement that it has to come from air capture," Seager said.
"But in the short term, these technologies have to get CO2 from somewhere, all of these technologies have to grow up, and it's a convenient source of CO2. It's part of the learning curve, I would say."
James Miller, a chemical engineer from Sandia National Laboratories, said the technology for manufacturing non-fossil fuels is mature, but the markets are not ready for it:
"From a technology point of view, can you do it? I think the short answer is you could do it tomorrow," he said. "Can you make money off it? In today's market, no."
Algernon's fuel is ready to go to market, Zenk said, but it needs policy support to assure investors that the market is stable enough to lower the risk of investment.
"We are now at the point where we can achieve commercial economics in our process," Zenk said. "It isn't that we can't produce low-priced fuels or competitively priced fuels, but in order to have a fair parity with the current set of incentives that are in place for fossil sources of energy, we need to have a system in place, whether its a renewable fuel standard or low-carbon fuel standard or another policy element, that provides parity with older technology."