Despite its several advantages, renewable energy, such as solar and wind power, is known for being considerably less efficient than traditional fossil fuels. As part of a new project, recently published in the Proceedings of the National Academy of Sciences, an international team of researchers has come up with an innovative power system, known as “hydricity”, which effectively combines solar energy with hydrogen fuel to ensure round-the-clock electricity production.
Envisioned by scientists from Purdue University and Switzerland-based Feredal Polytechnic School of Lausanne, the system features a thermal power plant that uses specially-designed solar concentrators to harvest sun’s energy. The concentrators focus the incidicent sunlight, which then heats water to superhigh temperatures of around 1,000 to 1,300 degrees Celsius. The resultant steam powers electricity-producing turbines, while a series of reactors splits the water into its constituent elements: hydrogen and oxygen. The former is stored for later use.
Although more efficient than standard photovoltaic cells, solar concentrators usually require bright direct sunlight to be able to gather adequate energy. To ensure continuous power generation even after the sun has set, hydricity features a second energy source – the stored hydrogen that provides additional power to drive the steam turbines. According to the team, the system, which uses both high-pressure and low-pressure turbines, can generate hydrogen at nearly 50-percent efficiency and electricity at an impressive efficiency of around 46-percent. Speaking about the research, Rakesh Agrawal, a professor at Purdue University’s School of Chemical Engineering, said:
Traditionally electricity production and hydrogen production have been studied in isolation, and what we have done is synergistically integrate these processes while also improving them. In the round-the-clock process we produce hydrogen and electricity during daylight, store hydrogen and oxygen, and then when solar energy is not available we use hydrogen to produce electricity using a turbine-based hydrogen-power cycle.
The set-up, the scientists claim, has a sun-to-electricity efficiency of nearly 35-percent, as measured in a 24-hour cycle. This brings it at par with the best PV and battery systems. The hydrogen, produced during the process, can have a variety of applications, including transportation, chemical industry and so on. What is more, using hydrogen fuel actually ensures zero greenhouse gas emissions. Agrawal added:
The concept provides an exciting opportunity to envision and create a sustainable economy to meet all the human needs including food, chemicals, transportation, heating and electricity… [It] combines processes already developed by other researchers while also improving on these existing processes. The daytime and night-time systems would use much of the same equipment, allowing them to segue seamlessly, representing an advantage over other battery-based solar technologies.
Hydricity exists only as a simulated computer model, with the researchers currently moving towards real-life experiments. The research is being funded jointly by the US Department of Energy and the National Science Foundation.
Source: Purdue University