Firming MENA Solar Power

Elpipes are one solution for exporting MENA power to Europe. I believe that single lines carrying at least  30 GW each will be needed for Continental scale grids, as suggested in these documents:

Arab_Construction_World_September_2010.pdf / HVDC_Africa_002c.pdf

My elpipes can go as high as 30 GW though a single line, with passive cooling, at around 1% resistive loss per 1000 km. They can get even bigger than 30 GW if the elpipes are actively cooled from the inside, or if sodium is used as the primary conductor (sodium is about one seventh as expensive as aluminum per unit conductivity per km).The only other known technology that can reach that transmission capacity in a passively cooled line are gas insulated lines (GIL) which I have discussed in other blog posts. GIL is based on sulfur hexafluoride gas (SF6) at fairly high pressure, and if a leak occurs the line can fail. SF6 is the most potent greenhouse gas ever measured, and has an estimated half life in the atmosphere around 3000 years.

I favor HVDC loops as the "unit project" of the supergrid. Loops are self-redundant, in that power can flow in a clockwise or a counterclockwise manner. If there are circuit breakers between each pair of nodes on the loop, then each node will always have power from at least one direction in case of a single fault. It is less expensive to balance the variable output of wind & solar using distant hydo resources (dispatchable hydro power and pumped storage) that to use batteries, for example; all that is required is that the solar power and balancing power be on the same HVDC loop. Dispatchable loads can also provide load leveling for solar power; things like pumping water (other than pumped storage), oxygen plants, desalanization, or aluminum smelters, for example. This paper, a draft of a paper I plan to submit to the Detroit General Meeting of the IEEE Power and Energy Society, looks at both energy storage and large dispatchable loads:

In the case of Africa it would be especially desirable to tie in Inga Falls and sea water based pumped storage at Danakil (below sea level land depression in Eritrea). Danakil's pumped storage could be about 600 GW-hours per daily cycle (allowing a one meter "tide" in the "Danakil sea."  By creating a single network that ties MENA solar into massive pumped storage at Danakil, Africa can export firm power to Europe, which is worth a lot more than variable solar output.

We also note that a lot of natural gas (so called "associated gas" that comes up with the oil) is flared at present near oil wells in the MENA; the existence of the HVDC loop would make it practical to run gas turbines and export the power. Gas turbines could operate as dispatched units to firm the MENA solar power. Firm power contracts are worth more money than the same amount of energy, but on a variable basis.

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