Notes on Spanish Solar Energy Plants (CSP)

At this moment, Spain has about 150 MW of thermo electric plants
 connected to the grid; some 750 MW are under construction and some 14 GW
 of these types of plants have requested license and have established the
 required bonds by the Spanish government. There are basically three
 types of plants:
 
 Mirrors with 2-axis trackers pointing to a boiler in a tower, with 10
 and 20 MW models, producing high temperature.
 
 Parabolic through mirrors with a tube in the longitudinal axis,
 collecting a fluid (synthetic oil at 400 Celsius) to a heat exchanger,
 usually molten salts coming from Chile, able to keep the system
 operating for at least 7 hours with this molten salt energy buffer, if
 clouds or similar appear. In the other side of the heat exchanger, steam
 is generated and a turbine is powered with it. If the lack of sun last
 longer, they connect the gas or fuel combined heating system. This is
 the most common system being installed and in operation today.
 
 A typical plant of 50 MW takes some 1,200 m*1,200 m and needs a water
 flow of 6 liters per second to refrigerate, which sometimes is a problem
 for the licenses in places where water is already very scarce, although
 they are studying some more complex alternatives with air refrigeration.
 
 Some of the plants do not have the heat exchanger and they just inject
 into the grid, when there is salt. The Spanish regulator has issued
 norms and strict regulations for these operators, to inform and predict
 the network operator and regulatory body of the energy generation
 forecasts every day in advance and every hour in advance, so that they
 are heavily penalized if they deviate ±5% from forecasts. However, they
 can modify in advance their forecasts and report the changes to the
 regulator, one day in advance for every next day and one hour in advance
 for every hour forecast. A number of companies has speciallized in
 wheater forecast, with thousands of sensors throughout the country and
 in the neighbouring countries, so that they know, when a storm is in the
 Atlantic, how much energy they will generate in a wind field (17 GW
 installed poweer and 12% national eelectricty consumption) 6 hours in
 advance. And for the sun, they have plenty of sensors throughout the
 country (pyranometers and others), so they know if the air is clear or
 not and if radiation will be in a zone at the level of 800 W/m2 or 570
 W/m2 well in advance.
 
 This is not marketing. This is a reality. Spain today is generating 17%
 of its electricty (some 340 TWh/year) by hydropower (a relatively dry
 country), 12% by wind and already 1% of solar power, going fast to 3-4%
 of solar power. Besides, there are other generations considered under
 “special regime” which are based in renewables, like waste burning and
 other biomass. And there is a strong a live debate on whether to shut
 down Garoña nuclear power plant (1% of the national electricity), after
 having reached to its life cycle or to extend another 10 years, with two
 strong groups debating in all media. The nuclear power contributes with
 20% to the national consumption (8 nuclear power reactors in 6 sites)
 
 The other big debate is how much a grid like the Spanish grid (almost an
 island, with small interconnections with France, Portugal and Morocco)
 could afford in renewables with intermitant generation. And if there are
 technical limits to the renewable systems. A couple of Portuguese
 institutions (now about 2,8 GW installed wind power) have mentioned that
 a probable peak in wind power for Portugal in suitable sites is in the
 range of 6 to 8,000 MW. Being Portugal four times smaller than Spain, we
 may guess that a level of 30,000 MW installed wind power (precisely the
 levels forecasted by 2020) may be close to wind fields classes (6 or 5)
 which make feasible now the installations. Promoters are struggling for
 fields with 2,000 hours nominal, as all other better fields are almost
 covered or not feasible (i.e. national parks, etc.) As for how much a
 grid like ours, with daily consumption peaks of 40,000 MW and night
 consumption valleys of 20,000 MW can afford in renewable penetration,
 there are many debates. The base load is already about 20,000 MW (the
 total night valley consumption) which can hardly be regulated (as it is
 supplied with nuclear and coal and working round the clock, with
 difficult regulation levels). So, when a day is very windy during the
 night, most of the 17,000 MW of wind power have to be automatically
 disconnected, with the frustration of the promoters of wind farms, which
 delay their return on investment. So a conventional fossil fuel back up
 is always necessary, but is working sometimes against the wind power.
 
 Pump up energy storage systems from dam to another upper dam are used,
 but only cover about 1.8 percent of the total national electricity and
 experts in the electric utilities doubt that could increase to
 significant levels, even we have a mountainous country with over 90% of
 the big river basins already occupied by dams.
 
 Solar is much more in line with daily consumption of electric energy,
 but is taking a big portion of agricultural lands (6 Ha per MW with
 trackers and 3 Ha/MW in fixed systems) and creating protests in the
 officials in the Ministry of Agriculture and some environmentalists,
 starting to see that renewables are sometimes not as “clean” as
 expected. Rooftop installations are not progressing, when talking in
 volume. Fixes are much more complex. Volumes on the ground make much
 more competitive tha in rooftop configurations. Legal problems also
 count. And the roofs are in most of the cases not well oriented or with
 plenty of shadows in urban environments, a critical issue for a system
 very much in the edge of energy and financial efficiency, even it is
 heavily subsidized by premium tariffs (at present level at 0,30€/kWh and
 coming down faster than technology improvements can match, because lack
 of financial resources, coming from a fossil fuel State and fossil
 fuelled society)
 
 From a Madrid contact
 Ferrand

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