To paraphrase from one of Agatha Christie's books, 'they do it with mirrors'. Not murder foul, but power clean!
Much of the argument against solar energy is about its costs and storage. But emerging from the shadow of PVs is a technology that avoids the common problems.
In the Andalucian desert of southern Spain, more than 1,000 mirrors, each about half the size of a tennis court, and with a collecting area of 120 sq km, are being carefully positioned. In January, when switched on the plant will start generating 20 MW of electricity. The power will be enough for 11,000 Spanish homes.
Part of the world's biggest solar tower plant, this uses the simple technology of reflecting sunlight to superheat water at a 160 metre high central tower. Here the concentrated light heats water to more than 260C, producing steam that can turn a turbine and generate electricity.
When switched on, the new plant will be the world's largest commercial CSP plant feeding electricity into a national grid.
This solar tower is part of a 300 MW solar farm which will supply power for 700,000 homes by 2013. It will include solar trough collectors and PVs.
The costs are high, double that of conventional power generation but as the project becomes larger, costs are expected to come down. In Spain, the feed-in tariff assures investors of a return for the power generated and fed into the grid.
Regarding the storage, solar thermal has an advantage over PVs as the excess heat can be stored in the form of molten salt from which the heat can be obtained when required. Almost 8 hours of solar energy can be stored by 28,000 tonnes of salt heated to 220 deg C.
In a country like India which recieves plentiful sunlight, CSP is a good option. But besides the parabolic trough system used to cook food, not much has been done. Why for instance can’t be vast expenses of Rajasthan’s deserts be used? Of course, water availability is a criteria but new technologies use air to cool the system. Maintenance is a bit intensive but labour should be no problem here.
Is there a clause for tax exemptions, subsidies only for proven technologies as in the US? Why haven’t entrepreneurs taken CSP here? Why can’t we adopt the feed-in tariff system?
Part of the world's biggest solar tower plant, this uses the simple technology of reflecting sunlight to superheat water at a 160 metre high central tower. Here the concentrated light heats water to more than 260C, producing steam that can turn a turbine and generate electricity.
When switched on, the new plant will be the world's largest commercial CSP plant feeding electricity into a national grid.
This solar tower is part of a 300 MW solar farm which will supply power for 700,000 homes by 2013. It will include solar trough collectors and PVs.
The costs are high, double that of conventional power generation but as the project becomes larger, costs are expected to come down. In Spain, the feed-in tariff assures investors of a return for the power generated and fed into the grid.
Regarding the storage, solar thermal has an advantage over PVs as the excess heat can be stored in the form of molten salt from which the heat can be obtained when required. Almost 8 hours of solar energy can be stored by 28,000 tonnes of salt heated to 220 deg C.
In a country like India which recieves plentiful sunlight, CSP is a good option. But besides the parabolic trough system used to cook food, not much has been done. Why for instance can’t be vast expenses of Rajasthan’s deserts be used? Of course, water availability is a criteria but new technologies use air to cool the system. Maintenance is a bit intensive but labour should be no problem here.
Is there a clause for tax exemptions, subsidies only for proven technologies as in the US? Why haven’t entrepreneurs taken CSP here? Why can’t we adopt the feed-in tariff system?
Any answers?
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2 comments:
Solar Power is undoubtedly cleanest source of the available technologies. Today, the biggest constraint in development of this technology is the exorbitant costs involved in per unit generation. Though the scholars claims that the cost will come down in future, but this is also a function of following variables:
1. Support from Govt Agencies
2. Breakthrough in technology
3. Scale of operation
Interestingly, in spite of the these variables, a few corporate houses have identified the potential in this technology and are coming up with decent proposals. Let us here share an example of Mukesh Ambani led Reliance Industries, which has entered into an agreement to sell solar energy to three power companies of Rajasthan - Jaipur
Discom, Ajmer Discom and Jodhpur Discom.
RIL is setting up a 5 MW solar power generation plant at Khimsar village in Nagaur district. Jaipur Discom Chairman R G Gupta said that the agreement is first of its kind to tap the solar energy for the benefit of consumers in the state.
"According to the agreement, RIL will get Rs 15.78 per unit. The power purchase rate would be Rs 3.67 for 10 years while Indian Renewable Energy Development Agency (IREDA) will pay Rs 11.33 per unit as per the directives of Renewable Energy Regulatory Commission (RERC) to promote solar green energy. Apart from that, the discoms will pay 78 paise per unit to the power generation company," he said.
The tariff and incentives will be applicable only if the plant is commissioned by December 2009. "As per the policy, IREDA will pay an incentive of Rs 11.33 per unit in the first year of operation, and for each subsequent year it would reduce it by 4 paise per unit.
"Subsequently, there will be an a 4 paise rise in tariff to compensate the overall payout to RIL," Gupta said. Electricity generation from solar energy is prohibitively expensive. The cost per megawatt in case of solar power comes around to Rs 24 crore while in case of wind power it is Rs 5 crore and Rs 4 crore in case of thermal power.
Lovers of Green energy are looking for more similar initiatives. But we shall also try to analyze, how feasible is it, economically, to generate power at Rs 15 in case of solar power plant compared to Rs 3 per unit in conventional electricity consumption? Is this Breakeven accepted to us?
Agreed, the costs of CSP are high, double that of conventional power generation. But as the project sizes becomes larger, costs are expected to come down. Costs also depend of availability of resource, and in this case insolation.
One way to address costs would be to adopt feed-in tariff. In Spain, long-term feed-in tariff (of 27 eurocents/kWh) for power from concentrating solar power plants of up to 50 MW, has seen the technology popularly adopted.
CSP costs have already begun to decline as production increases. According to a 2008 Sandia National Laboratory presentation, costs are projected to drop significantly when capacity exceeds 3,000 MW.
According to the director of the University of California's Energy Institute, solar thermal power will become cost competitive with other forms of power generation decades before photovoltaics will.
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