by Dave Elliott
A ‘Supergrid’ network across the EU and also connecting Northern Africa with Europe could help both regions reach a near-100% renewable energy share, with grid and market integration reducing overall energy costs. That’s according to a report published by Fraunhofer ISE in Germany, which involved five separate Fraunhofer institutes and saw some development work on system control hardware carried out alongside the desk studies. Similar ideas are also emerging in Asia, with a pan-Asian grid being proposed.
By Dave Elliott
It has been an eventful year for renewables. While progress continues apace, with renewables now supplying around 15% of electricity in the UK and 22% of global electricity, in this pre- Xmas post, rather than spelling out all the good news, I will look at some of the less good stories from the year- concerning wind power and CSP. (more…)
Deserts get a lot of sunlight and there is currently something of a race to develop and deploy the best technology to exploit this free energy.
Concentrating Solar Power (CSP) systems with mirrors, dishes or parabolic troughs focussing the sunlight to raise steam to run a turbines are currently in the lead. There have been some major developments in Spain and the USA, but also now in N Africa and the Middle East, with new projects opening in Morocco (the 470 MW Ain Beni Mathar hybrid project) and Egypt (the 150 MW Kuraymat hybrid project). And more are planned. For example, the UAE is planning a 100MW project, and the Egyptian National Plan for 2012 -17 includes a 100MW CSP plant in South Egypt, while the follow-up National Plan for 2018-2022 has 2,550 MW of CSP. The German-led Desertec project seeks to build on the CSP option, making supergrid links back to the EU. It has plans for a €600m 150MW CSP plant in Morocco as a first stage. www.desertec.org/
It’s hard to know what the impact of the recent political convulsions in North Africa may be, but CSP does seem likely to continue to move ahead in the region, as well as elsewhere- the largest CSP array so far planned is the 1 GW Blythe project, being developed in California by Solar Millennium LLC, on which more later.
A solar industry roadmap, as outlined in a study by A.T. Kearney and the European Solar Thermal Electricity Association, ESTELA, sees solar thermal reaching 12 GW of installed capacity globally by 2015, 30 GW by 2020 and between 60 and 100 GW by 2025. But that may prove to be pessimistic- CSP is not just limited to desert areas. For example, South Africa has a plan for a 5GW solar park, with the initial 1000MW phase, aimed for 2012, incorporating an already planned Eskom 100 MW CSP plant, which has received part funding from the World Bank. The Indian Ministry of New & Renewable Energy’s National Solar Mission aims to generate 20GW of grid linked solar power by 2022, 50% CSP. And in Australia a new ‘Zero Carbon Australia 2020’ report has 42.5 GW of CSP supplying 60% of total electricity there by 2020! http://beyondzeroemissions.org/zero-carbon-australia-2020
However a rival technology – Concentrating Photo Voltaic (CPV) power – may challenge CSP. CPV uses conventional solar cells but with large arrays and sunlight focussing arrangements, as with CSP. The crucial point is that mirrors are cheaper than solar cells. There are already some very large projects in existence, 20 MW or more globally, including the 4MW array in Springerville Arizona, and the 10MW Masdar project in the UAE. And costs are falling- some say faster than for CSP.
A GTM Research study claims that the growing market for CSP is being seriously challenged by the rapidly falling price of solar photovoltaics. GTM predicted that, although the CSP market will grow by around US$7 billion over the next two years, it will then tail off, due to the dramatic decrease in the cost of solar PV panels. So although CSP project costs are set to decline between 3% and 7% per year from 2010 to 2020, PV costs will also continue their own substantial declines, with PV expected to maintain a cost advantage (on both a cost-per-watt and cost-per-kWh basis).
In fact, some utility companies are already choosing PV over CSP for future solar plants. For example, Masdar, the Abu Dhabi government backed renewables company, had been backing CSP. Its $600m, 100 MW Shams 1 CSP unit should be completed in 2012. But the newly proposed 100MW Noor solar PV plant will cost less than Shams 1, because of improving efficiency and “the normal learning curve for the industry,” according to Frank Wouters, director of Masdar Power.
The cost battle is also evidently having an impact in the USA. According to an report carried by Renewable Energy World, conventional residential rooftop solar PV system in Los Angeles can deliver lower electricity at less cost per kilowatt-hour than the most cost effective, utility- scale concentrating solar power plant. It noted that CSP had higher operations costs and a higher cost of capital than for the residential rooftop system, and there were also transmission infrastructure and efficiency losses, which would increase the cost of power from the CSP plant further.
It may be too early to make longer-term policies on the basis of calculations like this, but PV and CSP do seem to be rivals. CSP has the major advantage of being able to store heat in molten salt heat stores, so that power production can be continued after the sun goes down, while most PV cell performance falls with time and rising temperature. But then CSP plants have to have some form of cooling as with any steam raising system- air cooling is less efficient than water cooling, but one thing deserts don’t have is water, so it would have to be piped in, adding to the cost. And with cell cost falling, PV may increasingly have the edge. After all, its not just domestic roof top PV systems or simply arrays that are in contention, new ideas for very large-scale CPV systems, including energy storage, are also emerging
Earthscans ‘Energy from the Desert’ three-volume book set edited By Kosuke Kurokawa et al , details the background and concept of Very Large Scale Photovoltaics (VLS-PC). Overall the authors are very optimistic- they say VLS-PV can be competitive with fossil fuel-fired plants assuming economic energy storage is available- they look to Vanadium flow batteries. And longer term they see large scale PV solar are becoming a dominant energy option.
CSP and CPV both have similar environmental impacts in terms of their land use footprint, with some projects in the USA falling foul of local concerns about desert wildlife, and CSP’s need for water.
But there should be plenty of desert areas around the world where there are minimal land use conflicts, and some North African CSP projects have been seen as being used partly for desalination- with sea water piped in over perhaps long distances from the Mediterranean, possibly linked to Solar greenhouses projects. www.seawatergreenhouse.com(http://www.seawatergreenhouse.com). www.saharaforestproject.com
New ideas may also emerge. It’s conceivable that CSP and CPV or PV arrays could be combined. There are some small-scale hybrid solar thermal-PV systems for domestic uses, the big advantage being that the solar heat absorbers keep the PV cells cooler, so they operate more efficiently, in tandem, with heat collectors in wafers in a sandwich with PV cells. Although it’s harder to see how this could be achieved with large scale focussing systems, it could be worth exploring in hot desert environments.
Hybrid CSP/PV systems were mentioned as a future option by the developer of the 1GW Blythe solar project in California mentioned earlier. Reflecting the changing fortunes of CSP and PV, it has now decided that the first 500-MW phase will be switched from CSP to PV technology because they say market conditions in the US now favour PV. But they also noted that CSP was a valuable ‘grid-stabilizing renewable energy source with storage capabilities,’ so a combination might prove to be the best option. www.powermag.com/POWERnews/3985.html?hq_e=el&hq_m=2269044&hq_l=45&hq_v=0c00b9b673
For more: Peter van der Vleuten, Free Energy International: