Are Emissions-Free Fossil Fuel Power Plants Too Good to be True?
Carbon capture and storage technology, which can bury up to 90 percent of the power plant emissions, according to the EPA shows promise but still has huge hurdles to overcome. The technology is expensive and unproven — the captured carbon must remain permanently trapped underground — and in requires massive public subsidies. All of the US-based projects, which are still in the demonstration phase, are publicly-financed in part.
However, Net Power thinks it is on the road to success. “You’re definitely not the first person to say that,” admits Walker Dimmig, a spokesman for Net Power, when asked if the company’s technology is too good to be true. Earlier this week the company said it is building a zero-emissions plant in Texas, which it says is a “first-of-a-kind.”
“Every piece of equipment except for the turbine is already in operation today,” Dimmig told Environmental Leader. “We’ve done thousands of thermodynamic models, and others have done the same. We’ve even tested the novel combustor that the turbine needs. Everything indicates this works the way we believe it does. And now we’re building the demo to confirm it. I guess you could say the only downside is that it doesn’t exist yet and we’re having to go prove it. We have a great deal of commercial interest, but since it’s a brand new technology, everyone wants to see if it will work.”
Dimmig says the company says it expects its future utility-scale power plants using Net Power technology will be able to sell electricity at a comparable cost natural gas power plants.
Net Power is a collaboration between Exelon Generation, CB&I, and 8 Rivers Capital. Almost two years ago the company announced it had secured funding for the $140 million project. This week it broke ground on the 50-megawatt demonstration plant in in La Porte, Texas.
The power plant uses Net Power’s power generation technology with inherent carbon capture, which means it doesn’t require expensive, efficiency-reducing carbon capture equipment.
“Traditional carbon capture approaches begin by assuming today’s best methods of power generation, such as natural gas combined cycle, are also the best starting point for developing a carbon capture system,” Dimmig explains. “So they design additive systems that bolt onto traditional plants to capture, cleanup and then compress their emissions streams. By their very nature, these systems will always be cost-additive to existing technologies: if you add a bunch of equipment, complexity, and processes that require energy, these systems will by necessity lower the efficiency and increase the capital cost of current plants. The only question is can we get those increased costs to an acceptable level; so far, it hasn’t worked out.”
Net Power, on the other hand, produces a high-pressure, high-quality CO2 stream that can be removed via a pipeline and sequestered or used in various industrial processes, including enhanced oil recovery.
The company says this works because:
- It uses CO2 (instead of steam) as the working fluid to drive a turbine. “So, when we go to remove part of that working fluid, it’s already in the condition needed to put it in a pipeline,” Dimmig says.
- The power plant uses an oxy-combustion system, which means it burns fuel with pure oxygen instead of air. This produces combustion products of CO2 and water, while eliminating NOx and other impurities. The system then removes water from this working fluid.
- It recycles the majority of the CO2 working fluid back into the front of the combustor, rather than using that hot CO2 to boil water and drive a steam turbine. “Because most of what we put into our combustor is hot, recycled CO2, we are able lower our oxygen needs, and therefore lower its overall cost impact on our system,” Dimmig says.
The demonstration plant will generate power that will be fed to the grid. Net Power expects commissioning to begin in late 2016 and be completed in 2017. The company says the 50MW plant will also provide the validation to begin constructing the first 295MWe, commercial-scale Net Power plants.
Lux Research analyst Daniel Choi says the major advantage of Net Power’s technology is that the emissions-free aspect. The company’s primary competition comes from companies developing carbon capture utilization and sequestration technologies; “however, because Net Power has a bottom-up approach to cleaner power generation — whereas CCU/CCS is fitted to traditionally designed plants — it is a promising long-term solution for new projects,” Choi says.
The downsides to Net Power’s technology involve cost — because the process requires an extremely pure oxygen stream, it needs to also build a cryogenic air separation unit, which is very capital intensive — and future finding, Choi says. Most of the $140 million Net Power raised in 2014 will be spent on the demonstration project, which means it will need to raise more money to build the 295 MW commercial plants.
“Overall, the company is well positioned to capitalize on the overall trend toward lowering carbon emissions,” Choi says. “The management team has a solid technical background, and the company is supported by major players. If the demonstration and planned commercial project are successful, NetPower may be able to fully take advantage of the shift from coal to natural gas power not only in the US, but possibly in other countries as well.”
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