The Japanese town turning cowpats into hydrogen fuel

In Japan, a smelly waste product is being reimagined as a potential clean fuel of the future that is powering cars and tractors.

We're being eyed suspiciously by dozens of cows. Their breath fogs cartoonishly from their nostrils.

It's a brisk morning in snowy Hokkaido, an island in the north of Japan. The cold air carries the distinct scent of cow manure – a smelly yet familiar side-effect of the region's thriving dairy industry. Accounting for 20% of the country's landmass, this island is the second-largest in Japan. It's also home to over a million cows, which produce over half of the country's milk and dairy products.

We are visiting one farm in Hokkaido that wants to transform the source of the pungent aroma in the air into something valuable. They are turning cattle manure into hydrogen. 

When it is burned, hydrogen does not emit carbon, making it an attractive alternative to fossil fuels. There are widespread hopes it could be used as a sustainable fuel to heat homes and power cars, trains, aircraft and ships in the future.

But the most common way of producing hydrogen today involves using methane – a fossil fuel piped up from deep underground, meaning it is still associated with significant carbon emissions. Hydrogen can also be produced by splitting water using electricity, but this can be expensive and is only low carbon if renewable sources of electricity are used.

The Shikaoi Hydrogen Farm, however, is using a different source – a waste product that there is no shortage of on Hokkaido. Around 20 million tonnes of cow manure is generated in Hokkaido annually. If not treated correctly, it can be an environmental burden, producing significant methane emissions as well as affecting water quality if allowed to leak into streams and rivers. So can it instead be used as a source of sustainable energy?

"This project to produce hydrogen from livestock manure originated in Japan and is unique to this place," says Maiko Abe from Air Water, one of several companies involved in the hydrogen farm project. We are visiting the facility in Shikaoi, a town in central Hokkaido, to film an upcoming episode of the BBC's TechXplore focusing on Japan. "Shikaoi accounts for 30% of Hokkaido’s cow waste and urine, so it has great potential for renewable energy."

Launched in 2015 by Japan’s Ministry of the Environment, the project aims to convert agricultural by-products into hydrogen to supply the local, rural community in a circular economy. The cow excrement and urine is collected from local dairy farms before being fed into a anaerobic digester at a central facility. Here bacteria break down the organic waste to produce biogas and a liquid fertiliser. The biogas is then purified into methane that is used to manufacture hydrogen.

The plant now has a hydrogen production capacity of 70 cubic metres (18,500 gallons), with an onsite fuelling station that can fill around 28 vehicles fitted with hydrogen fuel cells per day, says Abe. Although the fuel can be used by cars with fuel cells, the plant's fuelling station has been specially designed to accommodate agricultural vehicles such as tractors and forklift trucks. These farm vehicles are difficult to electrify with batteries due to their size and the type of work they do. The hydrogen-powered vehicles are used around the farms' sites, reducing the emissions that would otherwise be created by using other fuel sources. 

Cattle-made-hydrogen is also stored in canisters that are transported to provide power and heat to other facilities in the area, including a local sturgeon fish farm and the nearby Obihiro Zoo.

But hydrogen isn't without its problems. It needs to be stored in high-pressure tanks as a gas, and can be prone to leakage due to its low molecular weight. It can also degrade metal storage containers, leaving them embrittled, and is easily ignited and so requires additional safety precautions when handling it.

Hydrogen can also be stored as a liquid by chilling it to cryogenic temperatures of below –253C (-423F), but this can be energy intensive and requires large amounts of additional infrastructure.

Hydrogen has nearly three times the energy content of petrol (gasoline) when taken by mass alone. But its low molecular weight also means that by volume, the energy packed into a litre of liquid hydrogen is a quarter that of petrol. Put simply, as the lightest gas in the Universe, hydrogen takes up more space kilogram for kilogram than petrol. This means a lot more storage space is needed for hydrogen compared to fossil fuels like petrol, diesel and natural gas. It also means producing and storing it at scale can require large amounts of energy and infrastructure.

But as well as these hurdles, the hydrogen farm project in Hokkaido also faces other challenges specific to northern Japan's climate.

Hokkaido's subzero winters means new technologies are needed to produce the hydrogen stably without the small amounts of water vapour in the methane freezing.

Using agricultural waste as a methane source to produce hydrogen is relatively uncommon, but it ultimately uses the same process as is used to produce hydrogen from natural gas: steam reforming. Here, steam heated to 800C (1,472F) reacts with the methane to produce hydrogen, along with the byproducts carbon monoxide and carbon dioxide (CO2). 

In the case of cow manure, however, says Abe, the project remains sustainable as this carbon originated in the grass the cows grazed on: "Since it was originally in the atmosphere, it is considered carbon neutral."

In addition, it helps to prevent the methane that would otherwise have been emitted from the manure from getting into the atmosphere, where it is a potent greenhouse gas.

Leftover slurry from the manure after the biogas has been extracted is sprayed as fertiliser onto nearby fields, while formic acid – which is both used in and created by the processes – could be offered as a preservative for cattle feed, says Abe. 

Currently, the electricity needed to produce and store the hydrogen comes from the national grid. But Abe says there's potential to shift to green energy, given Hokkaido’s promising sea, wind and geothermal potential, thus reducing the carbon emissions of this electricity.

Still, other challenges remain. The high cost of the hydrogen compared to fossil fuels and low demand mean expanding the operation is difficult. 

"The construction costs of hydrogen stations are very high," says Abe. "Since hydrogen vehicles are not yet widespread, we're keeping our filling capacity low to manage initial investment. As adoption increases, we'll expand supply."

To encourage hydrogen vehicle adoption in the area, hydrogen prices are subsidised by the plant, matching the cost of petrol. Hydrogen refuelling stations are also being developed in major Hokkaido cities like Sapporo and Muroran.

Japan is the world leader in hydrogen vehicles and has invested considerably in developing the technology. But for now battery-powered electric vehicles remain cheaper than hydrogen powered ones.

Though it's unlikely that cow manure alone will ever meet Japan's hydrogen demand, it could contribute significantly, and Shikaoi is creating a model for a circular economy that it hopes will show how costs can fall with the economies of scale. 

And there is growing interest in other parts of the world in using waste materials to produce hydrogen, with pig dung, poultry waste and even coconut husks having been explored as potential feedstocks. In Thailand, vehicle manufacturer Toyota is even exploring the use of hydrogen made from chicken waste to fuel its vehicles.

Meanwhile, engineers at the University of Illinois Chicago in the US recently developed another promising method to make hydrogen involving manure. In their case, they used the manure, along with sugarcane waste and corn husks, to make biochar, a carbon-rich substance which vastly reduces the amount of electricity needed to convert water to hydrogen.

"We are the first group to show that you can produce hydrogen utilising biomass at a fraction of a volt," says Meenesh Singh, a chemical engineer at the University of Illinois Chicago who led the project.

In the southern Japanese city of Fukuoka, on Kyushu, meanwhile, another waste product is being used to produce hydrogen – and here the dung is from humans.

For more than a decade, hydrogen has been created at the city's sewage treatment plant for use in hydrogen-powered vehicles. Most recently it has been used to fuel a fleet of zero-emission rubbish trucks.

Akira Miyaoka, hydrogen utilisation manager for Fukuoka City, says trucks that transport daily products are the town's main source of CO2, rather than large factories as in many other cities. "So we are working to reduce CO2 emissions from commercial trucks," she says.

The initiative started as a collaboration between Kyushu University and Fukuoka City, but now involves several major companies including Toyota.

"Sewage is something that is steadily discharged every day in the daily lives of citizens, so by making effective use of that sewage and extracting hydrogen as energy, we can achieve local production and local consumption of energy," says Miyaoka. 

Generating hydrogen from human waste starts with water from various household sources – including showers, dishwashers and toilets – arriving at the treatment plant. As the water is cleaned, the residual sludge is kept as a source of biogas and converted into hydrogen. 

"Sewage and biogas contain various impurities, so the process begins with the process of removing those impurities, which I think is a little different from other hydrogen production processes," says Miyaoka.

In 2024, Toyota helped the city launch Japan’s first hydrogen-powered service vehicle fleet, including ambulances, delivery vans and bin trucks. Officials at the sewage treatment plant say it is capable of producing 300kg (661lbs) of hydrogen in 12 hours – enough to fuel 30 trucks. 

The rubbish trucks head out six nights each week, each collecting 1.7 tonnes (3,700lb) of rubbish, all while running silently and emission-free on the bodily waste of the people they are collecting other waste from.

Fukuoka's sewage-to-hydrogen fuelling station has been around since 2015, and several other countries around the world are now adopting a similar approach.

Concord Blue has developed waste-to-energy plants in Germany, India, Japan and the US, converting waste and biomass into hydrogen and bioenergy. Several water authorities in the UK are also working on projects to derive hydrogen from sewage.

A prototype race car has also been developed using sewage-derived hydrogen in the UK. The Warwick Manufacturing Group (WMG), in partnership with Severn Trent Water, is harnessing microbes that generate hydrogen fuel from waste. They anticipate the technology could hit the mainstream within five years, despite existing challenges. (Read about how sewage-powered cars could be the future of motorsport.)

On a larger scale, aviation accounts for 2% of global carbon emissions, and researchers in a UK lab have developed jet fuel made entirely from human sewage.

Still, despite the promise, all of these technologies have yet to be delivered at significant scale.

Whether in rural or city landscapes, the Japanese projects we've seen during in filming are inspiring because they have the local community at their heart.

While adoption of hydrogen cars has stalled, hydrogen truck adoption is increasing gradually and it is these larger heavier industrial vehicles that contribute most significantly per vehicle to greenhouse gas emissions.

By reimagining waste as a resource, these projects demonstrate that energy can be found in even the most unlikely of places.

* Paul Carter is the presenter of TechXplore. You can watch his report from the Shikaoi Hydrogen Farm and on other sustainable technologies in Japan in TechXplore Japan: From North to South when it airs on 15 March 2025 on BBC News.

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