As world oil prices skyrocket, thousands of households in energy-poor Japan are taking part in an ambitious experiment to use fuel cells to light and heat their homes.
Since the prime minister's official residence became the first house in the world to be equipped with a domestic fuel cell in 2005, about 3,000 households have signed up to have the grey boxes installed outside their homes.
The project aims to thrust Japan to the forefront of a "hydrogen society" that has kicked its addiction to fossil fuels and produces affordable energy while spewing out far less of the greenhouse gas that is blamed for global warming.
"The principle of fuel cells has been known since the end of the 14th century, but their first practical use was not until 1965, aboard the American spacecraft Gemini 5," said Michihiro Mohri, a senior vice president at Nippon Oil Corp.
The fuel cells produce electricity and hot water through a chemical reaction between oxygen and hydrogen extracted from natural gas or other fuels.
"The hydrogen needed can come from various sources - hydrocarbons, natural gas, bio mass or rubbish" to create methane, said Mohri.
While the fuel cells do not emit carbon dioxide, some is produced by the system during the process to extract hydrogen from natural gas, although less than traditional forms of power generation.
As well as producing electricity, the fuel cells also ensure a steady supply of hot water for households. With no motor inside, the machines are also silent.
"Households with the system are also no longer at the mercy of power cuts during natural disasters," said Mohri, an obvious plus for people living in one of the most earthquake-prone countries in the world.
The government-sponsored fuel cell scheme involves a clutch of Japanese energy and technology heavyweights including Nippon Oil, Tokyo Gas, Sanyo Electric, Toshiba, Matsushita Electric Industrial, Mitsubishi Heavy Industries and Toyota Motor.
The government estimates there could be demand for 550,000 domestic fuel cells a year in Japan within a few years. There are 48 million households in Japan, of which 25 million live in individual houses.
For now, however, the system is expensive at about two million yen, or some US$19,000, excluding installation.
Japanese automakers are also chasing the fuel cell dream, working to create a viable car which would produce power through a chemical reaction between hydrogen and oxygen and leaving water as the only by-product.