Introduction
Another concept which mitigates Global Warming by reducing ‘natural’ emissions of GHG.. this time methane which is currently locked up in coastal hydrate reserves and shallow gas reservoirs.

As the ocean warms and sea-levels change, coastal hydrate outcrops on the continental shelves are likely to be destabilized.. in fact there is evidence of this positive feedback mechanism during previous periods of destructively rapid warming, such as that which accompanied the great end-Permian extinction.

The HPM will harvest hydrates from the ‘vulnerable’ coastal zone where the water depth/ temp relation preserves hydrates now but probably not in the future. Counter-intuitively, even increases in ocean depth can trigger this de-stabilisation. By reducing release of methane into the sea/ atmosphere and instead using the gas to replace conventional fossil fuels, in a carbon-neutral energy conversion process (see Oxycell), several environmental advantages are gained.

Hydrates occur as crystalline deposits on the seafloor mixed with mud and stone. They are normally formed by deep methane permeating upwards through the rock sub-structure and coming into contact with water at the seabed.

A family of semi-floating concrete structures is employed to gather the hydrates by enclosing an area of seabed in their bell-shaped ‘skirts’ before breaking up the deposit with projectiles.

This is basically a variant on conventional offshore practice for ‘floating-out’ huge concrete platforms and performing subsea drilling operations.