“G ET THE hell out of our way and stop funding the oil companies. That’s the thing that pisses me off,” thunders Trevor Milton, boss of Nikola, an American startup making hydrogen-powered lorries. His rage is directed at the government, and not for nothing does he sound like Elon Musk, the other clean-energy maverick with a company named after Nikola Tesla, developer of the alternating-current electric motor. He and Mr Musk are engaged in a race to decarbonise road transport.

Nikola, based in Arizona, has pre-orders for 8,000 hydrogen-fuelled trucks that will compete with Tesla’s battery-powered “Semis”, as well as other zero-carbon juggernauts made by Volvo, Hyundai, BYD and others. Many dismiss batteries and hydrogen in trucking because of the weight and volume needed to move heavy loads over long distances. Though both types of engine are more energy-efficient than internal-combustion engines (see chart), neither produces as much power per litre as conventional fuels, so they need far more storage space. Hydrogen has the additional disadvantage that it takes lots of electricity to make.

Yet finding ways to decarbonise freight is becoming increasingly important, because its share of CO 2 emissions is likely to rise as that of increasingly electrified light transport declines. Currently lorries produce about 2.5bn tonnes of CO{-2} a year out of an estimated total for all transport of about 9.5bn tonnes (not to mention the air pollution they generate). But emission standards for trucks are rare, unlike those for cars, and it is a fragmented business with lots of owner-drivers who cannot easily be corralled into taking collective responsibility for tackling climate change.

Reducing road-freight emissions can take many forms. Sweden is trying out power lines along a short stretch of road for heavy vehicles to hook up to, as buses do in some cities. Policymakers are also encouraging companies to move more heavy goods by rail, which has lower carbon emissions and may also be electrified. Biofuels such as ethanol could be used more extensively to curb emissions from internal-combustion engines. But since 2008, when China introduced battery-powered rubbish trucks for the Beijing Olympics, the most popular approach has been to use batteries in short-haul transport, especially along predictable routes where recharging is easy. McKinsey, a consultancy, estimates that in Europe and America, light- and medium-duty electric lorries could become cost-competitive with diesel ones in the 2020s. Journeys of more than 800km (500 miles) are more problematic because the weight of large battery packs reduces the amount of cargo that a lorry can carry, and long battery-charging times—perhaps 90 minutes a go—can penalise drivers who get paid by the mile. Enter the Tesla Semi, which Mr Musk promises will be on the road in America in 2019, with four battery packs to speed up charging. Some Tesla specialists estimate that their fuel system will weigh two tons more than that of a 40-ton diesel truck, meaning smaller cargoes. But that may not put off all users, especially since firms that use them can claim to be cutting emissions, making their products more environmentally friendly. Enter, also, hydrogen fuel-cell vehicles, which have a driving range and refuelling time similar to those of conventional vehicles, and an exhaust that is just water vapour. Companies like Nikola could find themselves in the vanguard of the hydrogen economy before it extends to heating, shipping and heavy industry. But first they have to overcome three challenges that will affect the future of hydrogen as a whole: making it, using it and transporting it. Start with hydrogen’s main drawback: it has to be manufactured. On Earth it is rarely found in isolation, instead forming compounds like natural gas and water. About 95% of today’s industrial hydrogen comes from fossil fuels. The most common method of making it is steam-methane reforming ( SMR ), which uses a catalyst to separate hydrogen from natural gas and steam. This method is used extensively in the chemicals industry but produces lots of carbon dioxide, which needs to be captured if hydrogen is to be produced with low emissions (see diagram).

The cleaner way is to use zero-carbon electricity to run electrolysers that split water into hydrogen and oxygen. This is a power-hungry process. For every unit of energy used, only 0.8 units of hydrogen is produced. So the cost of electricity is crucial, accounting for perhaps three-quarters of the price of hydrogen. And the price of emitting CO 2 is negligible (at least until governments make it more realistic) giving SMR a big advantage. But the paltry share of hydrogen produced by electrolysis is expected to grow because the more renewables are installed, the more prices drop. The IEA says that recent renewables auctions in places like Chile and Morocco suggest power prices of about $30 a megawatt-hour. At that price, hydrogen could be produced at $2 per kilo, making it competitive with SMR , which costs $1-3 per kilo.

Higher demand for electrolysers will lower their price, too. Graham Cooley of ITM Power, a British company based in the city of Sheffield, says that the price of the electrolysers his firm produces has halved to £800 ($1,000) per kilowatt (k W ) in three years. (Others claim lower prices.) He puts this down mainly to volume production. ITM Power is currently building what it says will be the world’s largest Polymer Electrolyte Membrane ( PEM ) electrolyser, with a capacity of 10 MW , for Shell in Germany. Mr Cooley expects the cost of electrolysers to fall to about £400 a kilowatt by the mid-2020s.

The main technologies used for electrolysis are PEM and alkaline. Alkaline electrolysers are more established and cheaper, but bulkier. PEM is becoming cheaper and has faster response times, which works better with intermittent renewables, and can be used on a small scale, which is suitable for hydrogen refuelling stations.

Nikola has helped boost production of alkaline electrolysers. In June it awarded a contract to Nel—a Norwegian company that was once a part of Norsk Hydro, which built the first such electrolysers in 1927—to supply 448 of them, plus fuelling equipment for Nikola trucks. They will have a total capacity of 1,000 MW , or 1.5 times all the electrolysers Norway has produced since 1927. The lorries will be leased by Anheuser-Busch, an American brewer, and others.

Dickon Pinner of McKinsey, a consultancy, reckons that, though at present levels electrolysers are still “out of the money”, their costs could fall a lot through industrialisation, as has happened with wind and solar, especially if China embraces the technology. A price on carbon would also make them more attractive.

Not only will hydrogen have to be produced more cleanly and cheaply, the cost of using it as a fuel must also come down. The instrument of choice is the fuel cell, which works like electrolysis in reverse, turning hydrogen back into electricity and water to power an electric motor. Fuel cells are not new; they provided power for the spacecraft that put the Apollo astronauts on the Moon. But until now they have been too pricey for widespread terrestrial use. They feed hydrogen to an anode and air to a cathode. Both are sandwiched around an electrolyte. Hydrogen electrons released at the anode travel through an external circuit to the cathode, making electricity.

America’s Department of Energy says the cost of fuel cells for use in small vehicles, currently $53-60 per k W if produced at scale with the best available technology, will need to fall to $40 per k W to compete with internal-combustion engines. Fuel cells will also have to be more rugged and better able to operate in freezing weather, and more refuelling stations will be needed, along with better systems for getting the green hydrogen to them. Nikola’s Mr Milton says its electrolysers will be powered by solar power, wind farms and hydro, most of it coming from off-grid sources.

Making clean hydrogen at scale will also require supply chains. Setting up a new infrastructure for delivering it could be prohibitively costly, especially in developing countries. (Nel recently showed off its hydrogen filling stations, hand-assembled in Denmark and costing about €1m, or $1.14m, apiece.) Many of the best sources of renewable energy that could be used to power electrolysers are found in isolated places such as the Atacama Desert in Chile, Patagonia, Somalia, Tibet and Australia. Hydrogen is very hard to send through pipelines, and shipping it in liquid form requires very low temperatures and very high pressures.

Get on board

With encouragement from Japan, which wants to be a leader in the hydrogen economy, Australia is working on a solution to this that could also benefit another freight sector: shipping. Michael Dolan of the Commonwealth Scientific and Industrial Research Organisation ( CSIRO ), an Australian body, notes that as yet there are no ships that can move hydrogen as a liquid (other than space ships, which burn liquid hydrogen).

To avoid the drawbacks of liquefying hydrogen it can be converted into ammonia via the simpler (though energy-intensive) Haber-Bosch process. Counterintuitively, there is a greater mass of hydrogen in a litre of liquid ammonia than in one of liquid hydrogen. The ammonia can then be shipped in liquid form—and some of it could be used in ships’ engines if they are modified.

Hydrogen fuel-cell vehicles, alas, cannot burn ammonia, and so it would have to be converted back into hydrogen after shipping (at additional cost). In August, CSIRO demonstrated, with some excitement, that a Toyota Mirai and a Hyundai Nexo could be fuelled with high-purity hydrogen extracted from ammonia using its membrane technology. The membrane allows the hydrogen through while blocking other gases.

All this may put the world’s truckers closer to the post-carbon era. But to get the economies of scale to bring hydrogen costs well down, non-fossil energy needs other big drivers of demand. One, which may use carbon capture and storage, is heating.