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?
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, says:
This project to produce hydrogen from livestock manure originated in Japan and is unique to this place,
“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.
Producing and storing hydrogen at scale can require large amounts of energy and infrastructure
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.
Abe, says:
The construction costs of hydrogen stations are very high,
“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.”
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The Japanese town turning cowpats into hydrogen fuel, source
