Most CSP development to date has focused on grid-connected facilities, but there is emerging interest in off-grid applications. Of these, mining is one that could hold potential.
By Jason Deign
Mauritania is not a country that can boast many world records but one potentially surprising (albeit disputed) accolade is having the world’s longest train.
The freight machine that plies the lonely route between the mines at Zouérat in the north and Nouadhibou on the coast can measure around three kilometres in length.
Other takers for the longest-train record are the BHP Billiton Iron Ore line in Australia and the Sishen-Saldanha line in South Africa, which also have trains that regularly stretch across several kilometres.
Aside from their trivia value, these transportation monsters give an idea of the scale of mineral extraction operations in remote desert areas. The open cast mines at Zouérat are reported to contain reserves of 200 million tons of hematite quartz, for example.
Traditionally, such installations are too remote for grid connections to be financially viable. So they have relied on gas plants or even diesel generators to provide round-the-clock power.
Now that CSP is becoming a proven technology, however, could there be an argument for looking at it as an alternative power source? For a start, desert mining locations have no shortage of sunshine; in fact, many of them are in the areas in the world in terms of irradiation.
Nor would there be a problem in finding enough free land to build a solar field.
Water use might be an issue, but this is a challenge that is being faced, and overcome, in CSP plants around the world; and Brayton cycle turbines such as those being developed in Australia could get around the problem altogether.
Furthermore, if you look at infrastructure lifecycles, the 25-plus-years life of a CSP plant corresponds nicely with the multi-decade timeframes involved in mineral extraction.
As a result, says Dr Andrew Skumanich, founder and chief executive of SolarVision Consulting, CSP plants “in principle would work for mines, but you have to transport the materials in, as well as the competence.”
In the event, transportation might not be so much of an issue; the world’s longest trains could presumably take care of it. And in terms of construction, mines usually come with ready-made workforces, ranging from cheap manual labour to qualified engineers.
It is also true that many countries with desert mining operations are also rapidly growing in CSP expertise.
Australia, South Africa and the USA spring to mind, but even the Zouérat operations are currently being expanded by a Spanish building contractor, making access to Spain’s pool of CSP experience a very realistic option.
That leaves the question of cost. Clearly, CSP is not cheap. And it is even less so where storage is involved, which would be the ideal for round-the-clock operations. However, most of the outlay on a CSP plant is in the construction phase.
The power returns and costs thereafter are relatively steady and predictable. In contrast, the operating cost of conventional fuels is exacerbated by the need to get them to the mine in the first place, and can vary significantly over the lifetime of a mineral extraction programme.
This can have an impact on the profitability of mining operations, which is already subject to significant volatility on account of the market demand for ore.
It is not an argument that would carry much weight in the current low-gas-price environment, says Andrew Stiel, a CSP analyst with Bloomberg New Energy Finance.
However, he says: “In the future, and particularly in remote locations, if getting access to cheap gas becomes a constraint then something like solar thermal may become attractive.”
Meanwhile, though, CSP may yet have an ace up its sleeve as far as resource extraction is concerned. A company called GlassPoint, of Fremont, California, is commercialising the use of CSP not for electricity but as a heat source for enhanced oil recovery (EOR).
Using a glasshouse-like structure equipped with parabolic mirrors, the company claims it can deliver 90 barrels steam per acre a day, at 400°C and 2,500 pounds per square inch, to extract oil at US$3 per MMBtu.
“They argue that their process already checks out from an economic point of view,” notes Stiel.
And GlassPoint is not the only solar company focusing on EOR; the American CSP developer BrightSource last year teamed up with Chevron Technology Ventures for a pilot project at the oil company’s Coalinga Field.
“The solar thermal people are realising that they are generating heat at the end of the day, and that can be used for a variety of applications,” Stiel comments.
“Of course a thermal power plant doesn't just mean electricity. There can be quite a natural combination with generating electricity but also perhaps providing heat to whatever process may be required in the mine.”
As a result, he says: “I am surprised there has not been more show of intent in targeting mines… but perhaps these discussions are not public yet.”
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