Is mega solar power on the way, or will high costs keep it at bay?

It’s 35 ˚C in the shade. Often.

In Upington, a town in the arid, ironed-flat expanse of the Northern Cape, the extreme and persistent heat may cause some to become hot and bothered, but to Eskom it’s good news – because this is where the utility is consider-ing building its electricity-from-the-sun project.

(In fact, the Northern Cape every year records some of the highest aggregates of sunny days a year worldwide.) If Eskom takes the decision to go ahead with the project, it will be the first major solar-energy project in Africa, especially where the elec- tricity generated will be directed into the main power grid of a country.

It has been a long time in the making, with Eskom in 2001 already initiating a feasibility study to determine the choice between either a trough or central-receiver system for a 100-MW plant. In the end, the molten-salt type central-receiver technology was appointed the favourite.

In 2003, it was estimated that the project would cost around R2,2- billion. Now Eskom prefers not to talk about costs until a fresh feasibility study has been com- pleted, this time specifically on the central-receiver system.

However, the cost of such a system may seem less severe these days, especially against the background of Eskom’s preparing to fork out R97-billion in capital expenditure over the next five years as it moves ever closer to its maximum genera- tion capacity as South Africans scurry for their heaters with each cold front.

But, yes, R2-billion-plus for 100 MW of electricity remains steep.

However, again, what makes electricity from the sun such a heavy- weight in the power-generation ring is that it is clean, renewable energy, unlike the electricity produced by South Africa’s coal-fired power stations. These stations are currently used to produce more than 90% of South Africa’s power – also churning out vast amounts of carbon dioxide and some other rather nasty pollutants.

Eskom’s solar-power project is currently in the feasibility and environmental-impact assessment (EIA) phase. This is scheduled to be completed at the end of 2007, says Eskom resources and strategy division renewable-energy corporate specialist Dr Louis van Heerden.

“If approval is obtained, based on satisfactory results from the above phase, construction work can start as early as 2008,” he tells Engineering News in an exclusive interview.

The project has to satisfy three prerequisites before implement-ation, he notes, namely a positive record of decision on the EIA; resolving all outstanding technical issues; and an acceptable business case. The project will most likely be located in the Upington area, and will have a maximum capacity of 100 MW.

Van Heerden explains that central-receiver technology, which has now emerged centre stage, concentrates the sun’s energy through multiple large mirrors, using the concentrated thermal energy to produce steam to drive a conventional steam turbine for electricity generation. The energy concentration is achieved by a field of large sun-tracking mirrors (called heliostats), which reflect the sunlight to a receiver, mounted on a central tower in the middle of the mirror field. A heat-transfer medium (molten salt) is pumped through the receiver, absorbing the highly-concentrated radiation reflected by the heliostats. The heated fluid is then circulated through a heat exchanger, where the thermal energy is used to generate steam and power a turbine. Temperatures within the system can reach in the region of 600 ˚C.

Central-receiver technology is only one of many renewable-energy options currently under investigation by Eskom, says Van Heerden.

“However, given South Africa’s significant solar resource, Eskom feels that this technology could potentially provide significant benefits into the future. “Eskom has spent several years evaluating various concentrating solar technologies. The studies conducted have indicated that the central-receiver system has signifi- cant potential for local content in its manufacturing, as well as the highest potential for future cost reductions.” Cost is one of the pivotal issues around renewable-energy solutions, as they are not developed, researched or mass-produced on the same scale as conventional energy solutions, such as those around coal.

However, as resistance to pollution grows, so does the research, development and production of renewable-energy systems.

The cost projection of the Upington project will be finalised through the feasibility phase, says Van Heerden. However, it is anticipated that the generation cost will be substantially more than conventional methods currently in use in South Africa. (This is not surprising, as South Africa is currently credited with producing the world’s cheapest electricity – which makes it a difficult fight for any alternative energy source to win.) As far as capital expenditure goes, rudimentary maths shows that Eskom’s proposed new 2 250-MW coal-fired power station, in Limpopo, at a cost of R26-billion, requires a payout of R11,6-million a megawatt. Should the R2,2-billion still apply to solar technology – even then as nothing more than an estimate – it comes to R22-million a megawatt. However, as renewable-energy pundits have often pointed out in the past, coal is a depleting feedstock, while sunlight is abundant, free, nonpolluting and, galactic disasters aside, not likely to run out.

One of Eskom’s first forays into solar energy did not quite illustrate this technology to be the answer to the country’s energy woes.

The 18-m-high, R3-million, 25-kW solar dish erected next to the N1 between Tshwane and Johannesburg in 2001 served to illustrate that small production volumes and lack of research and development are still major inhibiting factors to some areas of the renewable- energy market. “The dish research project was completed earlier this year, with all the research questions answered,” says Van Heerden.

Eskom will not be proceeding with the technology, he adds.

“Mechanically, it works quite well, but the operating and control system is not sufficiently robust in this generation system and, as such, we regard the technology as pre-commercial at this stage. “The US-based supplier is planning on installing several units of the next-generation dish systems in the US, which may eventually move the technology to a commercially-viable and stable technology in future.”

Bright spark
The newly-crowned sun king resides in South Africa.

The University of Johannesburg’s Prof Vivian Alberts, from the department of physics, has developed solar panels that may just take this technology further into the main-stream, owing to the cost reductions he has achieved.

Alberts’ solar panels are thinner and cheaper than those produced anywhere else in the world – in fact, up to 50% cheaper – and they are set to be manufactured locally.

Currently, the standard panels used locally are imported. (Alberts’ cost estimates have in the past been scoffed at by many solar-panel importers, either on the grounds of impossibility, or that thin solar panels have a much shorter lifespan than conventional ones. However, he responds by saying that their reaction springs from a fear of losing business on a cost-comparison basis.) To use the sun as an electricity source, one needs a photovoltaic device, such as a solar panel, to transform solar radiation – sunlight – into electricity, explains Alberts.

The semiconductor used up to now to achieve this has been silicon, which is a rather expensive option, he adds.

Alberts, who, ironically, read his masters and doctorate in silicon- solar technology 12 years ago, decided there must be a less expensive, more effective semiconductor than silicon for the purposes of solar devices. “Silicon is actually a poor absorber of sunlight.” The solar panels typically in use in South Africa are based on a 350-micrometre-thick layer of silicon – which is the minimum requirement to absorb sunlight effectively. Alberts’ invention is five micro-metres thick, combining several semiconductor materials which are as effective, if not more so, than silicon, he believes.

As it uses no silicon, costs are dramatically lower. It makes use of normal window glass as a substrate, with – and this is where it gets complex – molybdenum applied as back contact, followed by the core component, being a compound semiconductor comprising five elements – copper, indium, gallium, selenium and sulphide, replacing the silicon – with cadmium sulphide as a buffer layer, followed by an intrinsic zinc oxide layer and, finally, a conductive zinc-oxide layer. “The most expensive part of the panel is the glass,” says Alberts.

“The pilot plant has shown the production cost per watt to be €0,95, verified for a 25-MW production facility, assuming a 10% efficiency and average production yield of 85%,” says Alberts.

All of this means a 60-W panel could finally have a price tag of roughly around R490, or R8 a Watt, compared to imported panels entering local soil at R30 to R40 a Watt, he notes. Worldwide production of Alberts’ solar panel is in the process of scaling up.

The University of Johannesburg has, for purposes of commercialisation of the photovoltaic technology, formed the company, Photovoltaic Technology Intellectual Property (PTIP). Following a technical and commercial assessment of the technology, PTIP, in August 2005, entered into a licence agreement with Germany’s IFE Thin Film Technology. Following restructuring, IFE became Johanna Solar Technology (JST), the universal successor of IFE. This completed, JST has now started construction of a €72-million manufacturing plant of 30-MW capacity in Brandenburg, Germany. Production is set to start in March 2007. JST has seven shareholders, including South Africa’s State-owned Central Energy Fund, Richemont-Venfin and Anglo Coal.

Alberts says Germany has been granted the first production licence of the thin-panel owing to the fact that the country has a well-established solar market, while South Africa’s is still in its infancy.

“While the details are at this stage confidential, PTIP concluded a second international licence and technology-transfer agreement in July,” says Alberts.

The second licensee is also an established and prominent role player in the existing international photo-voltaic markets, and produces, markets and distributes well-known silicon-based solar modules worldwide. This second company will start construction of a 30-MW manu-facturing plant in Europe, in January 2007, says Alberts, with production kicking off in December 2007. However, South Africa will not lose out on gaining economic benefit from the home-grown technology. PTIP, in association with its German partners, is currently developing a business plan which is intended to serve as a basis for procuring “not more than three strategic South African investors in a new local company to be formed by PTIP – which will be called NewCoSA”, Alberts tells Engineering News.

PTIP would license NewCoSA on an exclusive basis for the manu-facture of the thin-film panels in South Africa – which will be the first-ever large-scale solar-panel production line in the country – as well as the right to sublicense the technology in Africa, and islands in the continent’s proximity. PTIP and the IFE group will under- take the general planning and project management functions for the procurement, construction and erection of the first manufacturing plant in South Africa. It is projected that construction of the South African solar-panel manufacturing facility will start in 2007, with the first panels coming off the pro- duction line in early 2008.

It is intended that the solar modules produced in the respective plants in Europe and South Africa will be marketed and distributed under a unified brand name, which is still being negotiated. “The South African market presents unique challenges and it is foreseen that complete photovoltaic systems (including solar modules, storage devices and inverters) will be developed mainly for off-grid applications. “The ultimate aim is to develop the local markets in the medium to long term, while excess products will be exported to Europe, in the short term, to ensure an economically- viable industry,” notes Alberts.

He adds that he has been engaged in negotiations with a variety of prominent international and national companies and organisations that have shown support and interest in the project. “However, until now, we have had no formal discussions with Eskom.” Alberts has been patient in doing his bit to undo the high-cost straitjacket that has, to a large degree, kept the solar industry from develop- ing faster.

“The project has been developed over a period of more than 13 years from a research-and-development level to a commercial level. The success of the technology depends ultimately on the support of strategic investors internationally, as well as locally. The current developments, and especially the magnitude of the commercial ventures internationally, have exceeded all my initial expect-ations, and even my wildest dreams. The technology is now supported by a combination of strategic investors with a global presence and vast commercial experience in photovoltaics. “I truly believe that we have now set a solid platform from which we can develop and build a sustainable photovoltaic industry in South Africa,” says Alberts.

Pay up to clean up
Solardome is a solar hot-water system manufacturer, also specialising in solar-energy systems. It has been in the solar-power business for more than 35 years. The company is also a member of the Sustainable Energy Society of Southern Africa.

The company’s James Venter agrees that bringing down costs is pivotal to furthering solar technology, but that even more is needed.

He notes that for solar-generated electricity to become a reality in South Africa, it requires government support in the form of incentives for grid-tied systems, which is the case in many European countries that are actively promoting the use of cleaner energy.

Government grants or rebates for using cleaner energy will aid the customer in paying for the solar system he or she has installed, the price of which can vary around R150 000, says Venter.

On a cost comparison basis, he notes that the US Department of Energy estimated the consumer cost of coal vs photovoltaic at a ratio of 1:5 for residential, and 1:4 for commercial and industrial; how- ever, this does not take into account the procurement methods, environ-mental consequences or hidden costs of either.

“In general, the cost of solar systems has decreased 700% over the last 20 years and costs will continue to decrease – owing to technology, sure, but mainly manufacturing volume as more and more countries become involved.” He adds that South Africa has, to date, pursued mainly off-grid applications – which generally means providing solar energy, which is an expensive solution, to poor rural communities – while a grid-tied system is the most economical approach.

“Stand-alone battery systems are the most popular in South Africa, and also the most uneconomical option for photovoltaic systems,” says Venter.

Stand-alone systems require battery backup, which is expensive, while a grid-tied system can use the grid as a battery bank, pushing electricity into the system when not in use.

Venter adds that the economic return on a homeowner’s investment in solar energy is almost always measured in the value of the electri- city generated.

“This is a very narrow way of thinking as the displacement of electricity that you would have otherwise bought from your utility or energy service is of more importance in South Africa, which is currently short on electricity.

“This, along with protecting your electronic equipment and lights against erratic supply and power spikes, with the added benefit of a little self-efficiency, can double the value of the system. “Grid-tied systems can be metered separately and rewarded at a defined rate, related to the domestic tariff, or set by a government initiative.” Venter is fully supportive of any form of renewable energy, but does not regard Eskom’s Northern Cape solar project as the only solution to producing alternative electrical energy in South Africa.

“If the same funds are used to promote and subsidise privately-owned grid-tied alternative-energy systems, it would be of great benefit to the average homeowner as well as to Eskom,” says Venter, who views electricity from solar solutions as ideally suited to South Africa. Places like the Sunbelt states in the US, Latin America, most of Africa, the Middle East, India and Australia have an average of 5,5 hours of effective sunshine. However, South Africa, the Sahara, Saudi Arabia, central Australia, Peru and Bolivia have higher averages.

Professor Thomas Harms, of the University of Stellenbosch’s department of mechanical engineering, says for South Africa to generate electricity using the sun is certainly feasible.

However, feasible does not equate with affordable, which is why the current industry mainly supports a number of local manufacturers of solar thermal domestic water- heating equipment. “At the on-grid end-user level, while technological progress is still being made, it is not yet economical to install photovoltaic panels on your roof, especially given most municipalities’ low resale tariffs of Eskom’s power.” Harms did an electricity-gener- ation cost comparison for Engineering News. “If you look at base-load generation, such as a coal-power plant able to sell power to the grid 24 hours, located next to an easily-mined, sufficient-quality coal mine, and discounting the environmental footprint and rehabilitation costs at the end of the life cycle to simplify the matter, only a few people would, at present, argue that a first-off, bulk solar-power station could compete with the 15c/kWh generation cost of such a plant,” he explains.

However, Harms notes that the picture changes quite significantly if one looks at servicing morning and evening peak loads. “A shortage of peak power-generating plant capacity in South Africa means that base-load plants have to run intermittently at, say, more than 84 c/kWh. This is an arbitrary figure and depends on the load factors, such as during which part of the day the coal plant feeds power into the grid – the shorter the period, the more expensive it is.” Therefore, says Harms, a solar power station in South Africa, such as the one planned near Upington, would ideally first have to deliver at peak demand times to render it competitive, which means it has to incorporate energy storage. This does not make it only more expensive in terms of capital spend, but also more versatile as a power station.

“I would expect it to be able to deliver below the threshold of 84c/kWh suggested.” He adds that the high-temperature central-receiver option chosen by Eskom lends itself particularly well to thermal storage. He does note, however, that a hybrid of the central-receiver concept with the more proved parabolic- trough concept, could eventually lower the visual impact of such a plant, and reduce performance risks.

In general, Harms is optimistic about the envisaged plant.

“Depending on how quickly it is realised, the solar power station will be one of the largest single-site solar power plants in the world. “The innovation should lift us to where we belong, namely being the world leader in solar-energy tech-nology and exporters thereof.” In addition, he expects that the plant will act as a net scientific and tourist attraction, which he regards as an important consideration. “I would regard it an unqualified wise and welcome contribution to the diversification of our energy production landscape, and a good step forward towards the long-term solar-based energy future many foresee.” Harms does, however, note that South Africa’s attempts at implement- ing renewable energy in general could do with some generous aid, such as increased funding prioritised for renewable-energy research and skills development.

“We also need higher electricity tariffs, which will, no doubt, come with Eskom’s R97-billion five-year capital-expenditure programme.

“While this will be detrimental to some sectors of the economy, it will lead to the development of new sectors,” he notes.

This also applies to tighter emission controls. “This is painful, but that is what change for the better is all about,” says Harms.

Courtesy: Engineering News