Modular nuclear reactors promise cost-competitive hydrogen production
NuScale Power has released the results of a new evaluation that indicates that a single small nuclear NuScale Power Module (NPM) could economically produce almost 50 tonnes of hydrogen fuel per day. The study, originally conducted by the Idaho National Laboratory, says that the improved power output of the NPM allows it to produce 20 percent more hydrogen from water than previously.
The prospect of a hydrogen economy suggests a promising alternative to conventional power sources based on fossil fuels. For example, a hydrogen-powered motor car that burns the gas in a fuel cell to create electricity would have the eco-friendly, zero-emissions footprint of an electric car, but without the need for the eco-unfriendly battery banks, the slow charging times, and limited range.
However, a hydrogen infrastructure suffers from one major snag. Unlike fossil fuels, hydrogen doesn't exist in tappable deposits like natural gas. It has to be extracted from more complex molecules using large amounts of energy. In fact, 95 percent of the hydrogen produced in the world today comes directly from fossil fuels, with the biggest supply coming from steam methane reforming, where a mixture of steam and methane gas is put under high pressure while in contact with a nickel catalyst, to produce hydrogen, carbon monoxide and a small amount of carbon dioxide.
Around the world, scientists and engineers have been looking at ways to get around this by creating new catalysts or ways to split water into its component hydrogen and oxygen molecules using sunlight to either power an electrolysis process or to provide heat to crack the water molecules apart at high temperatures. The problem is that solar hydrogen plants can only work on a sunny day, don't scale well, and have a massive real estate footprint.
One plant proposed by the University of Colorado, for example, would use five 732-foot-tall (223-m) towers illuminated by 21.5 million square feet (two million sq m) of heliostat mirrors in a plant covering 1,200 acres (485 ha). For all that, it would produce 100 tonnes (222,400 lb) of hydrogen per day.
Those figures suggest the solar plant is twice as productive as an NPM, but NuScale says that its nuclear modules are designed to scale up by adding as many of the factory-built nuclear reactors as needed at a site. According to the new study, a single module generates 250 MW of heat or 77 MW of electricity. One, five, a dozen, or more such reactors could be installed on a site smaller than a conventional power station and located almost anywhere.
The method that NuScale uses to produce hydrogen is based on superheated steam and electricity. Water is heated to a temperature of 300 °C (572 °F) by the reactor and then the temperature of the steam is increased to 860 °C (1,580 °F) using two percent (around 1.8 MW) of the reactor's electrical output. This is then put through a high-temperature steam electrolysis system that works like a fuel cell in reverse. By pumping thermal energy into the system, the water breaks up into hydrogen and oxygen rather than combining the gases into water to get out energy.
According to NuScale, the process is cost competitive and by using nuclear reactors that also generate electricity, the small modular reactors can be switched into and out of hydrogen production as the demand for electricity fluctuates. In addition, the Oregon-based company estimates that a single NPM would reduce carbon dioxide emissions by 168,000 tonnes per year.
NuScale did not explain why a small nuclear reactor should be used for hydrogen production rather than a larger conventional reactor, but it's likely a matter of economics where a small reactor could affordably be purposed for hydrogen production where a larger and more expensive reactor couldn't be.
"The ability of our NPM to now produce even more clean hydrogen, in a smaller footprint, is yet another example of how NuScale’s technology can help decarbonize various sectors of the economy while providing additional revenue streams for customers," says Dr. José Reyes, Chief Technology Officer and Co-founder of NuScale Power. "Coupled with our proven design, unparalleled safety, and load following capabilities, this analysis further demonstrates that NuScale’s design is the gold standard in helping meet the demand for innovative solutions to challenging global energy needs."
Source: NuScale Power