THE WAY TO BIG SUN

Technology Roadmap; Concentrating Solar Power
11 May 2010 (International Energy Agency)

THE POINT
The International Energy Agency (IEA) is not known for utopian enthusiasm about a New Energy future. It has traditionally been interested in oil, natural gas and coal. So the IEA’s Technology Roadmap; Concentrating Solar Power is a genuine indication that the handwriting (about the coming New Energy economy) is on the wall and even the most traditionally fossil foolish see it.

The CSP Roadmap describes the kind of sun (direct normal irradiance, DNI) that is needed for the several technologies that use the sun’s heat to boil water, create steam and drive a turbine to generate electricity. CSP, used in solar power plants (SPPs), requires high clear skies and intense direct heat. It is ideally suited for the world's arid, semi-arid and higher altitude deserts. Built in places with the right DNI, the IEA paper says, CSP can provide 11.3% of the world’s power by 2050. (Technology Roadmap; Solar photovoltaic energy, the IEA's companion study on the more familiar rooftop solar PV technology that uses the sun's light to make electricity, will be examined later this week.)

This is a conservative piece of research. Concentrating Solar Power Global Outlook, a 2009 paper from Greenpeace, the European Solar Thermal Electricity Association and SolarPACES (solar specialists within the IEA), found it was possible for CSP to provide 7% of world power by 2030 and a quarter of world power by mid-century. (See GREENPEACE LIKES SUN IN THE DESERT)

What is actually possible for CSP simply remains to be seen. So little CSP has been built and put to work that it is almost impossible – and yet deeply intriguing – to imagine what solar power plants might do as developers prove their competing technologies, build economies of scale and bring costs down to grid competitive levels.

A recent Stanford University paper suggested a concerted effort in the U.S. could develop 49,000 CSP megawatts by 2030 from its 300 megawatts today. (See A Plan for a Sustainable Future…by 2030). Another study of the CSP potential in the Middle East and North Africa (MENA) hypothesized that nations there could get all or most of the needed 80-to-90 gigawatts of new generation from CSP by 2017. (See MIDEAST WASTING POTENTIAL AS BIG AS THE SUN…) The MENA study suggested CSP will achieve grid parity by 2025.

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Many of the New Energies are still working hard to build the economies of scale that will drive their costs down to grid parity. But CSP is probably the only one that is getting a boost from the fossil fuels industries. At present, and at least (according to the IEA) through 2025, CSP’s best use is as a peak load smoothing generation source. CSP is most productive just when the most intense sun causes air conditioners to kick on and demand for electricity rises sharply. Developers are, therefore, being given the opportunity to build solar power plants adjacent to coal and natural gas facilities in “hybrid” configurations.

When demand peaks, the price of power is highest and CSP’s high cost is less out of line with the cost of adding extra fossil fuel generation. In addition, CSP-generated electricity can often ramp up quicker than extra coal or gas generation can be called on. Because fossil fuel plant builders can readily see the advantages CSP offers, they are spending for new hybrid capacity and the spending is helping CSP move toward the economies of scale it needs to bring its price down.

Finally, CSP technologies offer a crucial advantage over the PV solar technology that does not use the sun’s heat but converts the sun’s light to electricity. Electricity cannot be cost effectively and efficiently stored in large quantities for significant lengths of time. The heat captured by some CSP technologies (especially parabolic trough and power tower plants) can be stored in the form of heated and pressurized molten salts. The molten salts can be released after the sun has set or passed behind a cloud cover to generate more electricity. This storage potential could eventually allow CSP solar power plants to serve as a base-load power supply on a 24/7 basis.

The U.S. Department of Energy (DOE) goal is for CSP to reach intermediate load grid parity by 2015 at ~US$100 per megawatt-hour and to reach base-load grid parity by 2020 at ~US$50 per megawatt-hour. The IAE Roadmap sees those CSP price parities coming in 2020 and 2025-2030.

Peak load is 10% of all electricity demand, intermediate load is 50% and base-load is the other 40%. For this reason, CSP has lots of room to grow by meeting the first 60% of demand.

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THE DETAILS
The first commercial-scale CSP plants began operating in California between 1984 and 1991, thanks to federal and state tax incentives and mandatory long-term power purchase contracts. When fossil fuel prices plunged in the late 1980s and early 1990s and the incentives expired, developers stopped building and advancing CSP. In 2006, in response to global climate change, rising fossil fuel prices and new financial incentives, the CSP market reemerged in Spain and the U.S. Southwest.

The CSP theoretical potential is enormous. The assets in the U.S. Southwest could meet the entire U.S. electricity demand several times over. The Middle East and North Africa could supply about 100 times the present electricity demand of the Middle East, North Africa and the EU.

The 4 main CSP technologies: (1) parabolic troughs, (2) Linear fresnel receivers, (3) power towers, and (4) parabolic dishes. Parabolic troughs currently dominate but the other types are gaining market share.

All types of CSP concentrate heat energy from the sun to very high temperatures at a receiver. The heat is used to generate steam which is transformed into mechanical energy by turbines or other engines which generate electricity.

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In early 2010 there was ~1 gigawatt of CSP capacity worldwide. There are also 15 gigawatts of projects in development or under construction in 12 or more countries (including China, India, Morocco, Spain and the U. S.).

Each CSP technology has multiple components: (1) mirrors/heliostats, (2) receivers, (3) heat transfer and/or working fluids, (4) storage, (5) power blocks comparable to traditional power plant turbine systems, (6) plumbing for cooling steam in the power block, and (7) control and integration IT systems. CSP is used primarily for electricity generatrion but also lends itself to (1) desalination, (2) heating and (3) transport fuel syntheses such as the compression of natural gas and the conversion of electricity to hydrogen for storage in fuel cells. CSP can be applied both as (1) bulk power and (2) distributed, decentralized generation.

CSP incentives could be (1) feed-in tariffs or above-retail premiums, (2) binding Renewable Electricity Standards (RESs) with solar-specific targets requiring regulated utilities to obtain a specific portion of their power from solar energy by a specified year, (3) capacity payments and/or (4) fiscal incentives such as production or investment tax credits.

By 2050, CSP could generate 11.3% of the world’s electricity, 9.6% from solar heat and 1.7% from backup fossil fuels or biomass-generated biogas.

Direct Normal Irradiance (DNI) is the energy received on a surface perpendicular to the sun's rays. It is measured with a pyrheliometer. The measurement is an approximation of a CSP facility’s capacity.

Direct Normal Irradiance (DNI) is 80%-to-90% of the solar energy hitting the Earth’s surface on clear days. On cloudy and foggy days, DNI is essentially zero. DNI is needed for CSP to generate the temperatures required to drive the CSP process. It is most often in arid and semi-arid regions (where skies are typically clear) between 15° to 40° latitudes North and South and at high altitudes.

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DNI for CSP needs to be at least 1900 kWh/m2/year and 2100 kWh/m2/year. Below that, solar PV would be more efficiently productive.

The best CSP assets: North Africa, southern Africa, the Middle East, northwestern India, the southwestern U.S., Mexico, Peru, Chile, the western part of China and Australia.

Possible CSP assets: the extreme south of Europe and Turkey, other parts of the U.S. South, Central Asia, parts of Brazil, Argentina, and China (especially the Northeast).

Where DNI is adequate, CSP will achieve grid parity as a peak and intermediate load power source by 2020 and become base-load power by or before 2030.

The IEA expects North America to be the biggest CSP producer and consumer, with Africa, India and the Middle East following. Northern Africa is likely to export a significant amount of CSP-generated electricity to the EU if current trans-Mediterranean transmission plans are realized.

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CSP can also (1) supply supplementary process heat for industrial processes, (2) do co-generation by simultaneously heating, cooling and supplying power, and (3) serve as a source of water desalination in places where the sun is intense and fresh water is in short supply.

The biggest technical obstacle CSP faces may be its high requirement for a wet cooling water supply. Developers are addressing this issue with new dry or hybrid dry/wet cooling technologies.

There are 2 non-technical obstacles for CSP: (1) finding open lands for the sprawling facilities that do not face environmental impacts challenges and (2) getting adequate transmission from the empty, under-populated, desert regions where the resource is rich to the high-population, energy-hungry urban load centers.

Without storage capability, CSP plants need at least 2 hectares per megawatt estimated (MWe). Storage would require more land.

By mid-century, the IEA expects CSP to be utilized in the production of enough liquid or gaseous hydrogen to displace ~3% of world natural gas use and ~3% of the world liquid fuel use.

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The IEA Roadmap includes sections detailing (1) Transport and Export of CSP, (2) the Technologies (parabolic trough, linear fresnel, parabolic dishes, solar towers and others), (3) Storage, (4) Grid integration, and (5) Cooling and other water issues.

The IEA Roadmap identifies a series of key actions national governments can take to support the development of CSP capacity by driving investment for research, development, demonstration and deployment (RDD&D):
(1) Dedicate long-term funding for RD&D;
(2) Advance ground and satellite measurement and modelling of DNI globally;
(3) Support development of long-term, predictable, solar-specific incentives;
(4) Require regulated utilities to bid for CSP production;
(5) Eliminate limits on CSP at hybrid plants and reward hybrid plants only for their CSP output and not their fossil fuel output; and
(6) Streamline permitting and access for CSP and hybrid facilities.

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The IEA Roadmap suggests policy makers develop these actions to achieve a specific series of milestones in a coherent timeline: First, incentives and infrastructure must drive CSP to overcome economic barriers; second, CSP will need innovative financing so as to cope with high upfront costs and limited initial returns; third, there must be incentives to assist CSP in overcoming non-economic barriers; fourth, policy makers must assure adequate research, development and deployment (RD&D); finally, policy makers must provide incentives that allow growth in developing nations with rich CSP assets.

CSP SPPs built between now and 2020 will mostly serve as intermediate and peak loads management. By 2020-to-2025, the first High Voltage Direct Current transmission lines connecting CSP SPPs to high demand urban centers should be in place, allowing proliferating CSP capacity to begin serving as base-load power.

In the 2025-to-2030 period, CSP technologies are expected to have the economies of scale that allow them to achieve grid parity, opening the technology up to greater development.

After 2030, CSP will begin providing “solar fuels” such as compressed natural and biomass gas and liquid hydrogen to the world’s energy mix.

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By 2050, CSP is expected to be accounting for ~11 % of world electricity generation.

At present, CSP costs are high above other sources of grid electricity. These costs will fall as circumstances (transmission, technology advances, economies of scale, etc.) coalesce to allow CSP to move from a source of peak and intermediate load power to base-load power.

Utility-scale state-of-the-art trough plants currently cost US$4.20 per watt to US$ 8.40 per watt. Variables include labor costs, land costs, technologies, DNI and, most significantly, the amount of storage and the amount of available land.

Costs per watt are expected to decrease 12% if a plant goes from 50 megawatts to 100 megawatts and 20% if it is 200 megawatts. Costs for the power block (turbine), balance of plant and grid connection are expected to decrease 20%-to-25% as a plant doubles in size.

Technologies allowing plants to work at higher temperatures are expected to cut costs 10%-to-20%. A 15%-to-25% increase in efficiency is expected to cut overall cost 20%.

Present trough plant costs are expected to fall 40% overall in the next decade.

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The solar power tower technologies could cut SPP installation costs 40%-to-75% due to the use of flat rather than parabolic mirrors. Many believe the power tower concept is the one that will dominate CSP growth in emerging economies.

CSP operation and maintenance (O&M) costs: (1) plant operation, (2) hybrid fuel, (3) feed water/cooling water, (4) field maintenance. A typical 50 megawatt trough plant employs 30 for operation and 10 for maintenance. Costs are estimated at US$13-to-US$ 30 per megawatt-hour.

Financing plans vary but are generally higher than for fossil fuel plants because the technology remains untrusted by financing sources.

Lifetime annualized generation costs for large trough SPPs are currently estimated at US$200-to-US$295 per megawatt-hour. The key variable seems to be real DNI. Storage technology at present allows too little extra generating time to significantly affect price.

Current storage technology has the most value in allowing utilities to bring extra generation on with a minimal time delay.

Advances in storage and the pricing of greenhouse gas emissions are the factors most likely to move the cost of CSP-generated electricity most quickly to grid parity. Until it is reached, CSP SPPs will have their highest value in offsetting peak and intermediate loads in the heat of summer days when CSP capacity matches the rising demand of air conditioners.

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QUOTES
- From IEA’s CSP Roadmap: “Concentrating solar power can contribute significantly to the world’s energy supply…[T]his decade is a critical window of opportunity during which CSP could become a competitive source of electrical power to meet peak and intermediate loads in the sunniest parts of the world…The overall aim of this roadmap is to identify actions required – on the part of all stakeholders – to accelerate CSP deployment globally. Many countries, particularly in emerging regions, are only just beginning to develop CSP. Accordingly, milestone dates should be considered as indicative of urgency, rather than as absolutes…”

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- From IEA’s CSP Roadmap: “The possibility of integrated thermal storage is an important feature of CSP plants, and virtually all of them have fuel-power backup capacity. Thus, CSP offers firm, flexible electrical production capacity to utilities and grid operators while also enabling effective management of a greater share of variable energy from other renewable sources…”

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- From IEA’s CSP Roadmap: “CSP uses renewable solar resource to generate electricity while producing very low levels of greenhouse-gas emissions. Thus, it has strong potential to be a key technology for mitigating climate change. In addition, the flexibility of CSP plants enhances energy security. Unlike solar photovoltaic (PV) technologies, CSP has an inherent capacity to store heat energy…[so] CSP plants can continue to produce electricity even when clouds block the sun or after sundown. CSP plants can also be equipped with backup power from combustible fuels. These factors give CSP the ability to provide reliable electricity that can be dispatched to the grid when needed, including after sunset to match late evening peak demand or even around the clock to meet base-load demand…[D]ue to these characteristics, CSP can also be seen as an enabling technology to help integrate on grids larger amounts of variable renewable resources such as solar PV or wind power…”