Four Phi Suea solar homes being developed in Chiang Mai, Thailand, will convert excess energy into hydrogen and store it in fuel cells.
Here is how the energy system functions: During daytime, excess solar power from PV panels is directed to run electrolyzers and produce hydrogen. Said hydrogen can then be transformed back into electricity using a fuel cell storage system at night.
Some 114 kW of photovoltaic panels will be capable of generating around 441 kWh of daily electricity. Excess electricity will be stored in two 2,000-Ah lead-acid battery banks. Electrolyzers will then convert additional excess power into hydrogen gas by applying an electrical current to water. The hydrogen will then be stored until it is needed, typically at night, at which point it will be changed back into electricity using fuel cells.
According to the US Department of Energy, “Hydrogen can be stored physically as either a gas or a liquid. Storage of hydrogen as a gas typically requires high-pressure tanks (350–700 bar [5,000–10,000 psi] tank pressure). Storage of hydrogen as a liquid requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is −252.8°C. Hydrogen can also be stored on the surfaces of solids (by adsorption) or within solids (by absorption).”
An electrolyzer is an electrochemical apparatus designed to perform electrolysis: splitting a solution into the atoms from which it is made by passing electricity through it. Electrolysis was pioneered in the 18th century by British chemist Sir Humphry Davy (1778–1829).
“It’s a dream to have 24-hour access to the power of the sun. With our renewable power system and hydrogen energy storage, we have fulfilled this dream,” said Sebastian-Justus Schmidt, initiator of the Phi Suea House project.
According to the developer, the first phase of the development has been completed and the energy system has entered the testing phase with the first three buildings. The system, states Thailand-based CNX Construction, is expected to be 100% operational when construction is completed at the end of 2015.
“The technology behind this system is still very new. There are some systems already running in labs at leading universities worldwide and small numbers of similar hydrogen energy storages have been deployed as backup power systems for telecommunications in remote areas, but the Phi Suea House is the first project worldwide where this ground-breaking technology is being used as the main energy storage for a multi-house residential development.”
CNX says the energy conversion process is entirely clean, with oxygen and water being its only byproducts.
When fully up and running, the system will reportedly be able to produce hydrogen at a maximum rate of 2,000 l (440 gal) every hour and will be able to store up to 90,000 l (19,800 gal). The daily demand for electricity is expected be around 200 kWh. The fuel cells will be able to produce 120 kWh at full storage, which should be adequate for nighttime use.
Images via CNX Construction