Solar Thermal Electricity (STE) and Climate Change Mitigation

Euro-Arab Training Course on
“Smart Grids and Integration of Renewable Energies”
April 25-29, 2016. Granada (Spain)
Eduardo Zarza
CIEMAT-Plataforma Solar de Almería,
Apartado 22, Tabernas, E-04200 Almería
E-mail: eduardo.zarza@psa.es
Solar Thermal Electricity (STE)
and Climate Change Mitigation

Euro-Arab Training Course on “Smart Gridsand Integration of Renewable Energy”
STE and Climate Change Mitigation
• Introduction to STE plants
Content
• ClimateChange and STE Plants
• Conclusions
• The Spanish experience with STE Plants
• Integration of STE Plants into Smart Grids

State-of-the-art of STE Plants
What is a Solar Thermal Electricity (STE) plant ?
A STE plant is a system where direct solar radiation is concentrated and then
converted into thermal energy at medium/high temperature (300ºC – 800ºC).
This thermal energy is then converted into electricity by a thermodynamic cycle.

Thermal
Storage
Fossil backup
Direct solar radiation
OPTICAL CONCENTRATOR
Concentrated
solar radiation
RECEIVER
Useful
heat
Waste heat
Mechanical energy
Thermodynamic
Cycle
G
Electricity
Simplified Scheme of a Solar Thermal Electricity (STE) Plant

There are four different technologies:
Technologies available for STE plants:
 Central receiver technology

100 m
Heliostatfield
Receiver
Power Conversion
System
Tower
Central Receiver STE Plant

State-of-the-Art
• Depending on the fluid delivered by the receiver there are three different
technologies: a)saturated steam
View of the tower
Aerial view of PS-10 and PS-20 plants (saturated steam)
Liquid water
Saturated steam (40 bar)
Condenser
GeneratorTurbine
Steam storage
system
Receiver Saturated-steam plant

State-of-the-Art
The IVANPAH Project (377 MWe, 150bar/555ºC steam)IVANPAH Unit 1 in operation (125 MWe)
technologies: a)saturated steam, b) superheated steam

State-of-the-Art
Molten-salt plant
Aerial view of the 19 MWe plant GEMASOLAR (Spain)
technologies: a)saturated steam, b) superheated steam, and c) molten salts

 Parabolic trough collectors
Technologies available for CSTP plants:

Parabolic Trough Collector
Receiver Tube
Parabolic trough concentrator
Structure
A typical parabolic trough collector

Solar field
Power Conversion System
Solar Power Plant with Parabolic Trough Collectors

State-of-the-Art
Scheme of a typical HTF plant with parabolic trough collectors
• The technology fully proven is the HTF (Heat Transfer Fluid) technology, with or
without molten-salt storage systems
295 ºC Oil
395 ºC Oil
Steam
generator
Deaerator
Reheater
Oil expansion vessel
Steam turbine
Condenser
G
SolarField
Preheater
Superheated Steam (104bar/380ºC)
Reheated steam 17bar/371ºC
G(hot tank)
(385ºC)
Molten salts
(Hot tank)
Molten salts
(Cold tank)
(285ºC)

 Stirling dishes
State-of-the-art of CSTP Plants

ConcentratorReceiver
Estructure
Stirling Dish
Stirling engine

State-of-the-Art
• Several designs have been developed (the 3-kWe and 25-kWeAmerican
designs and the 10 kWeEuropean design). However, no commercial plan
is in operation
Stirling Dish
The 10kWe Envirodish designThe 25kWe design by SES3kW Stirling dish (EEUU)

 Stirling dishes
 Compact Linear Fresnel reflectors
State-of-the-art of CSTP Plants

Receiver pipe
Rectangular reflectors
Compact Linear Fresnel Reflector (CLFR)

 Primary energy supply is dominated by fossil fuels at present
Energy in the World: Global Context
STE

• There is growing concern about climate change and environmental pollution
 The use of renewable energy sources must be boosted quickly
• The current concentration of GHG in the atmosphere is 375 ppm, and it must
be kept below 450 ppm to avoid irreversible environmental damage (global
temperature increase over 2ºC)
• 164 different global scenarios have been analysed by the Intergovernmental
Panel for Climate Change (IPCC) which showed that the renewable
energy share of primary energy consumption must be greatly increased
(about 17% in 2030 and 27% in 2050). For this, the global cumulative
investment required in the power generation sector is much less than 1% of
the world GDP.
Energy in the World: Global Context

 The primary energy source (solar radiation) is practically
unlimited and available worldwide
 It is clean energy with a great potential for cost reduction
 Electricity can be easily transported over long distances at
affordable costs
STE plants can significantly help to reduce the use of fossil
fuels, because:
Can Solar Thermal Electricity Plants be of Help ?

 The primary energy source (solar radiation) is practically
unlimited and available worldwide
The Sun is a huge nuclear reactor emitting 3.8x1023 kW of radiant power
The Earth intercepts only a small fraction (1.7x1014 kW). However:
Many countries have a high or good level of solar radiation
(Argelia can produce 30 times the electricity consumption of the EU)
 Solar radiation reaching 1 m2 of the Earth’s surface in a year is equivalent
to 1.3 barrels of oil
 The world’s electricity demand could be supplied by the solar radiation
existing in 1%-2% of the arid zones on Earth
 Solar radiation on the Earth’s surface is 7,000 times the world primary
energy demand

PotencialComercial de los S.S.T.C
25

 CSP technologies deliver clean energy and have a great potential
for cost reduction
Source: ESTELA / ATKearney, Junio 2010
Cost projections for CSP technology
Cost reduction achieved by PV
and wind technologies
PV: 70% cost reduction from 5$/W (1998) to 1.4$/W (2010)
Wind: 60% cost reduction from 4.3$/W (1984) to 1.4$/W (2010)

affordable costs
 800 kV DC power lines can easily transport electricity over 3000 km at
an affordable extra cost (< 20 €/MWh). 90% of World population lives within
a distance of less than 3000 km from sunny places.

Sunny places and distance to the rest of the World

affordable costs
 800 kV DC power lines can easily transport electricity over 3000 km at
an affordable extra cost (< 20 €/MWh). 90% of World population lives within
a distance of less than 3000 km from sunny places.
The MENA region is a “solar mine” that may be the perfect region for
a significant commercial deployment of STP plants that would be used not
only to meet local electricity demand, but also to export electricity to
Europe (DESERTEC-EUMENA Proposal). The electricity loss with 800 kVDC
power transmission lines is less than 10% for a distance of3000 km

The Spanish Experience with STE Plants
 There are 50 STE plants in Spain since 2013 are they all are in routine
operation, showing a great reliability and dispatchability
45 PT plants (2222,5 MWe):
- Parabolic trough technology:
 Eighteen 50MWe-plants with 1GWhtTES
 One 22.5MWe-planthybridized with biomass
 Twenty six 50MWe-plants without TES
3 CR plants (49,9 MWe):
 Two saturated steam receiverplants
(10MWe and 20MWe)
 One molten salt receiver plant (19,9MWe)
- Central receiver technology:
2 LF plants (31,4 MWe), with saturated
steam and no thermal storage system
- Compact Linear Fresnel technology:

 Total yearly production in 2015:
5113 GWh (89 GWh more than in
2014) accounting for 2% of total
electricity demand in Spain
Monthly record of 889 GWh in July

Monthly production
record889 GWh
Historic production of STE plants in Spain
Yearly production
record5.113 GWh

STE (MWe)Total demand (GWh)
Typical Summer day
Peak contribution to the total
electricity consumption > 8 % in
Summer months
Max. daily contribution over 5%
Monthly contribution of 4% to the
Spanish electricity market in Summer
months
 Total yearly production in 2015:
5113 GWh (89 GWh more than in
2014) accounting for 2% of total
electricity demand in Spain
Monthly record of 889 GWh in July

Good matching between STE production and demand in Spain
These curves show how well STE production matches the demand
Electricity demand (MWh) STE production (MWh)
Demand STE production

On-line information of the Spanish electricity market at https://demanda.ree.es/demanda.html

 Commercial deployment of STE plants has been aimed so far at mass
production of electricity and they are connected to large electricity networks
STE Plants and Smart Grids
3 x50 MW, 7 h TES
ANDASOL Plants (Granada, Spain)

The IVANPAH project (377 Mwe, 150bar/555ºC steam)
IVANPAH Unit 1 en operación (125 MWe)

Disco Stirling de 3 kWe (EEUU)
 However, STE plants with Striling Dishes are very modular and can be used
for small plants (from 2-3 kWe upwards)

 However, STE plants with Stirling Dishes are very modular and can be used
 Parabolic trough collectors and linear Fresnel concentrators can be
implemented at small size to produce electricity coupled to Organic Rankine
cycles for power units lower than 100kW
 Central Receiver plant designs for 100 kW are already commercially
available, hybridized with natural gas to guarantee electricity production at
any time

100 kWe STE plant with Central Receiver (AORA-Solar)

 However, STE plants with Striling Dishes are very modular and can be used
 Parabolic trough collectors and linera Fresnel concentrators can be
implemented at small size to produce electricity coupled to Organic Rankine
cycles for power units lower than 100kW
 Central Receiver plant designs for 100 kW are already commercially
available, hybridized with natural gas to guarantee electricity production at
any time
 The high dispatchability of STE plants make them specially suitable for
their integration in Smart Grids.

Conclusions
 Solar Thermal Electricity (STE) plants are a technically feasible option to
supply a significant fraction of the world energy demand
 Though current cost of electricity produced by solar thermal power plants is
still high, there is a large potential for cost reduction in a medium to long term
 The Spanish experience concerning reliability and dispatchability of STE
plants is very positive
 STE technologies are feasible for both mass production of electricity and
integration into small smart grids.

The largest R+D centre in the World for STE Technologies :
Plataforma Solar de Almería (PSA)
STE Plants and Climate Change Mitigation

Euro-Arab Training Course on
“Smart Grids and Integration of Renewable Energies”
April 25-29, 2016. Granada (Spain)
Eduardo Zarza
CIEMAT-Plataforma Solar de Almería,
Apartado 22, Tabernas, E-04200 Almería
E-mail: eduardo.zarza@psa.es
Solar Thermal Electricity (STE)
and Climate Change Mitigation
! Thank you for your attention ¡

Solar Thermal Electricity (STE) and Climate Change Mitigation

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Solar Thermal Electricity (STE) and Climate Change Mitigation