How do you get 20m tonnes of grain out of Ukraine?

theguardian.com:

A clock is ticking inside the towering, multistorey warehouses on the quayside at the Black Sea port of Odesa on the Ukrainian coast.

One huge metal structure alone contains a quarter of a million tonnes of grain, yet represents just over 1% of the estimated 20m tonnes trapped in Ukraine since the Russian invasion began in late February.

Hundreds more of these “grain elevators” are scattered across the world’s fifth-biggest wheat exporting country: next to roads, at railway terminals, and at ports. Yet still full of last year’s harvest, these towers are already almost at capacity.

In just over a month the spring harvest gets under way, when farmers begin collecting the winter wheat, which will need to find its way to Ukraine’s grain silos. Meanwhile, inflation is soaring, countries such as India are blocking wheat exports, and the risk of famine is growing.

Pressure is building for an international agreement on a rescue mission for Ukraine’s grain, which is desperately needed to feed the world, and which Kyiv urgently wants to sell to get its hands on vital foreign currency. Ukraine produces as much as half the world’s sunflower seeds, a tenth of its wheat and up to a fifth of barley and rapeseed.

As well as a huge diplomatic effort, rescuing Ukraine’s grain also represents a vexing logistical challenge. Given the vast quantities involved, the majority of Ukrainian grain has always been transported by sea rather than road or rail.

Turkey – which has the authority over sea traffic entering and leaving the Black Sea – is thought to be leading conversations with Russia about proposals to allow grain ships from Ukraine through a naval corridor to the Bosphorus.

However, several problems need to be solved to ensure the safe