<aside> ⚠️ Problem statement: Trucks account for 5% of the world’s total greenhouse gas emissions. Renewable diesel poises a perfect solution to transition the trucking industry to net zero emissions. The largest factor holding renewable diesel back from large-scale adoption is the high price of green hydrogen. Green hydrogen is a critical component of renewable diesel manufacturing but is twice as expensive as regular hydrogen because of the catalyst material used in the production process of green hydrogen which is responsible for 60% of the total cost of green hydrogen.
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Transportation is the world’s largest source of greenhouse gases. Three-quarters of the world’s cargo is carried by ocean-going ships. Despite this, trucks are the real culprit of greenhouse gas emissions: trucks make up [62%](https://climate.mit.edu/explainers/freight-transportation#:~:text=Breaking down freight emissions,62%25%2C of freight's emissions.), of cargo transportation emissions, accounting for 5% of the world’s total greenhouse gas emissions.
While an obvious solution may be battery-powered trucks, a massive barrier is that they require 8X more batteries than a passenger electric vehicle. The weight of all these batteries is roughly 1200lbs, accounting for 35% of the [42000lb](https://www.xtl.com/portal/much-freight-fits-full-truckload/#:~:text=Some light truck%2Ftrailer combinations,44%2C000 lbs for a truckload.) cargo weight limit, greatly decreasing the amount of cargo the truck can carry.
The best way to transfer the trucking industry to net zero emissions is renewable diesel; green diesel is produced from biomass sources that do not use fossil fuels.
Renewable diesel must be made with green hydrogen. However, green hydrogen is twice as expensive as regular hydrogen produced by fossil fuels, averaging $3.70/kg. This is the biggest barrier to large-scale adoption of renewable diesel.
Green hydrogen is produced through an energy-intensive method of extracting hydrogen from water through electrolysis. The most common electrolyzer used for green hydrogen production is a proton exchange membrane electrolyzer (PEM).
PEM electrolysis process
PEM electrolyzers use a water-based acidic polymer membrane for its electrolyte, with platinum electrodes. The process starts at the anode, where the protons are separated from the electrons and pass through the membrane to the cathode side of the cell. On the opposite side of the cell (the cathode side), the precious metal electrode combines the protons and electrons with oxygen to produce water, which is the only bi-product of the process. When current is applied to the battery, the water is split into two parts: hydrogen and oxygen. Hydrogen passes through the membrane to form hydrogen gas.
Diagram of the status quo of green hydrogen production
The high price of green hydrogen is due to the cost of one of the primary components: a platinum catalyst. This is what allows the water-splitting reaction. Platinum is part of the platinum group of metals, the rarest metals on Earth. There are only 5 parts per billion by weight in Earth’s crust, making it 30 times rarer than gold. The low availability of platinum makes it the most expensive metal, averaging $1200 per ounce.
As a result, platinum represents 60% of the total cost of the electrolyzer, directly impacting the ability to scale this technology.
Alternative electrolyzers such as solid oxide electrolysis cells exist, which allow for much cheaper materials such as ceramics to be used as electrocatalysts. Instead of using water, they separate steam to produce hydrogen. Because of this, these electrolyzers operate at a minimum of 400 degrees Celsius to be effective and are most effective at 700 degrees Celsius.
Solid oxide fuel cell diagram