A proposed energy conversion process for making solar ...energy.mit.edu/wp-content/uploads/2016/09/A-proposed-energy-conv… · MITEI Sep 2016 6 Fundamental Requirements 1. Use clean,

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A proposed energy conversion process for making solar energy a major player in global

power generation

Jacob Karni

The Weizmann Institute of ScienceRehovot, Israel

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General Objective of Renewable Power Generation and Fuel Production

Have an energy conversion method, which can gradually replace fossil fuel combustion on a worldwide scale,

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General Objective of Renewable Power Generation and Fuel Production

Have an energy conversion method, which can gradually replace fossil fuel combustion on a worldwide scale, eventually leading to a renewable-dominant global energy supply.

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Fundamental Requirements1. Use clean, renewable energy, with

benign environmental effects

2. Large-scale (hence, modular)

3. Supply energy year-round, 24/7 Get me what I want, when I want it !!!

4. Transport energy over long distances

5. Affordable cost

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5. Affordable cost

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5. Affordable cost

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5. Affordable cost

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5. Affordable cost

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5. Affordable cost

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Levelized Energy Cost

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• The LEC defines the breakeven cost of thesystem.

• It is the basic cost/performance parameter ofpower generation systems

The acronym LCOE (Levelized Cost of Energy) is often used instead of LEC

The Levelized Energy Cost

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Total capital invested in construction and installation

Annual operation and maintenance

Annual fuel costs

Net annual electricity production

LEC =fcr ⋅ Cinvest + CO&M + C fuel

Eelec,yr

Cinvest

CO&M

C fuel

Eelec,yr

fcr =kd 1+ kd( )N

1+ kd( )N −1+ kinsurance Annualized Fixed Charge Rate

(or Annuity Factor) Real debt interest rate

Depreciation period in years (system design life)

Annual insurance cost rate

kd

kinsuranceN

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Annual fuel costs



Eelec,yr

Cinvest

CO&M

C fuel

Eelec,yr

fcr =kd 1+ kd( )N





kd

kinsuranceN

HereweareonlyinterestedinthesolarLEC

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Annual fuel costs


LEC = fcr ⋅ Cinvest + CO&M

Eelec,yr

Cinvest

CO&M

Eelec,yr

fcr =kd 1+ kd( )N





kd

kinsuranceN

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Net annual solar electricity production

Annual-average system efficiency

Sunlight collection aperture area

Direct annual solar irradiation energy

Cinvest

CO&M

Esolar−elec,yr

LECsolar =fcr ⋅ Cinvest + CO&M

Esolar−elec,yr

=fcr ⋅ Cinvest + CO&M

ηsys,yr−avgAcollector aperture Iincident dttyear ,sun

∫

ηsys,yr−avg

Acollector apertureIincident dt

tyear ,sun

∫

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Annual-average system efficiency



Cinvest

CO&M

Esolar−elec,yr


Esolar−elec,yr



∫

ηsys,yr−avg


tyear ,sun

∫

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LEC Reduction



∫

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LEC Reduction



∫

1. Select a site with good solar conditionsNot unique to any technology

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LEC Reduction



∫

1. Select a site with good solar conditions

2. Obtain favorable financing to minimize fcrNot unique to any technology

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LEC Reduction



∫


2. Obtain favorable financing to minimize fcr.

3. Lower production, installation and operation costsNot really unique to any technology

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LEC Reduction



∫



3. Lower production, installation and operation costs

4. Increase the overall annual system efficiency.

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LEC Reduction



∫




4. Increase the overall annual system efficiency. Increasing the collector area causes an increase in costs and generally does not reduce the LEC.

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LEC Reduction







∫

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LEC Reduction



∫

• Increasing the overall annual system efficiencyis usually combined with reduction of production, installation and operation costs.

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LEC Reduction



∫


• We must develop systems with a potential for higher annual-average system efficiency than possible in present solar systems.

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General Features of Solar-Thermal Systems

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General Features of Solar-Thermal Systems

• There is an energy loss in each step

• The overall annual-average system efficiency is

Where ηi are the annual-average component efficiencies.

!!!

!!!

Annual-averageefficiency≠ “DesignEfficiency”

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Now we are ready to deal with theFundamental Requirements

1. Use clean, renewable energy, with benign environmental effects


3. Supply energy year-round, 24/7Get me what I want, when I want it !!!


5. Affordable cost

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Solar System are Modular by Nature

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Large Scale, Modular Design

~375 MWe Plant near Ivanpah, CA, with 3 Solar Towers

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~150 MWe Trough Plant near Ouarzazate, Morocco with a single Power Conversion Unit [Relatively long heat transmission lines]

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~150 MWe Trough Plant near Ouarzazate, Morocco with a single Power Conversion Unit [Relatively long heat transmission lines]

Firstof3CSPmodules

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Solar System are Modular by Nature

But what should be the size of each module?

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Primary Optics of Solar Tower

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PS10 – Abengoa’s~10MWe plant near Seville, Spain

Size – Optics Relation in Solar Tower Systems

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Size – Optics Relation in Solar Tower Systems PS10 – Abengoa’s~10MWe plant near Seville, Spain. 624 x 120m2 heliostats

115m high tower

PS20 – Abengoa’s~20MWe plant near Seville, Spain 1255 x 120m2 heliostats;

165m high tower

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115m high tower


165m high tower

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115m high tower


165m high tower

As good as possible 2:1 scale up

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115m high tower


165m high tower

As good as possible 2:1 scale upReceiver aperture diameter is increased by ~ !

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Gemasolar – Torresol’s ~20 MWe plant with 15 hours of thermal storage, covering nearly 2 km2. 2,650 x 120m2 heliostats; 140m high tower


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Forcedtouse360° radiation’scollectionandexternalreceiver

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BrightSource’s solar power generation plants near Ivanpah, CA; 3 solar towers, totaling ~375MWe, covering ~16 km2. 173,500 x 15m2 heliostats; 140m high tower

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ReceiverAperture

SpilledRadiation

Concentrating Dish

– Spillage Losses –

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ReceiverAperture

SpilledRadiation

ReceiverAperture

SpilledRadiation

Concentrating Dish

Solar Tower ~10MWe


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Solar Tower > 20MWe

Receiver

SpilledRadiation

ReceiverAperture

SpilledRadiation

ReceiverAperture

SpilledRadiation

Concentrating Dish

Solar Tower ~10MWe


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ReceiverAperture

SpilledRadiation

Solar Tower > 20MWeEfficiency of External Receiver < Efficiency of Cavity Receiver


Receiver

SpilledRadiation

ReceiverAperture

SpilledRadiation

Concentrating Dish

Solar Tower ~10MWe


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Energy Storage in Solar Systems

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Wind Output

Load Required

The TXU (Arizona) Load Requirement

Electrical Power Generation and Distribution

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Solar Output

Wind Output

Load Required

Electrical Power Generation and Distribution The TXU (Arizona) Load Requirement

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Electricity demand and load distribution between Coal (Steam Turbines), Nat. Gas (Combined Cycle, Gas Turbines), Nuclear and Wind in the UK.

Demand

CoalGas(CC) Nuclear

Wind

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Demand

Coal Gas Nuclear

Wind

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Demand

Coal Gas Nuclear

Wind

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Demand

Coal Gas Nuclear

Wind

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Large scale intermittent renewable solutions must include enough

storage to assure power supply per demand

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Supply solar energy year-round, 24/7 1. Adding storage to a solar power system requires an

increase of the power input during solar hours, meaning larger collection area.But the size of the power conversion unit does not increase

2. Larger collection area means• lower optical and receiver efficiencies in Solar

Tower systems• lower heat transmission efficiency in Trough

systems.

3. The optical and transmission efficiency of small solar towers is least affected by an increase of collection area

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systems.


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systems.


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systems.


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systems.


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Requirements for having storage without increasing the LEC, relative to a solar system of the same size, without storage:

1. Increasing collection area does not cause efficiency reduction of other system components

2. The added storage cost does not exceed the eliminated cost of increasing the power conversion unit.

Supply solar energy year-round, 24/7

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Power Conversion Units for Solar-Thermal Systems

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Power Conversion Units Options for Solar Systems

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

0 200 400 600 800 1000 1200 1400 1600

PC

U E

ffic

ienc

y

T_high (engine)

Carnot Efficiency

C-N Efficiency

Free-Piston StirlingSteam-Rankine

Brayton

Combined Cycle

sCO2 Brayton

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

0 200 400 600 800 1000 1200 1400 1600

PC

U E

ffic

ienc

y

T_high (engine)

Carnot Efficiency

C-N Efficiency


Brayton

Combined Cycle

sCO2 Brayton


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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

0 200 400 600 800 1000 1200 1400 1600

PC

U E

ffic

ienc

y

T_high (engine)

Carnot Efficiency

C-N Efficiency


Brayton

Combined Cycle

sCO2 Brayton

• Available at the optimum temperature range for solar-thermal• Available at relatively small sizes (1MWe and larger)

Supercritical CO2 turbine advantages:


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Use of Solar Energy for Fuel Production from CO2 and Water

Enable Long Distance Energy Transportation

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Dissociation of CO2 using concentrated solar energy

CourtesyofNewCO2Fuels(NCF)andtheWeizmannInstituteofScience

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Dissociation of CO2 using concentrated solar energy

CourtesyofNewCO2Fuels(NCF)andtheWeizmannInstituteofScience

To be discussed in a future talk…

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The Proposed System

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System ConfigurationSolar Power Generation

Heliostats

Receiver

Power Conversion

Unit

Sloping Ground

ConcentratedSunlight

Secondary Reflector

1

3

6

5

4

Storage

Electricity Output

2

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Heliostats

Receiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage

Electricity Output

Primary Optics[MIT]

2

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• Our Design: Relatively small (~10-15 MWt), high-efficiency module. • Increase system efficiency translates to smaller collection area.

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2.5 MWt Solar Tower near Pentakomo CyprusCourtesy of the Cyprus Institute

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Receiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage

Electricity Output

2

Heliostats

Secondary Optics and Receiver[Weizmann]

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Receiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage

Electricity Output

2

Heliostats

Storage[Alumina Energy]

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Receiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage

Electricity Output

2

Heliostats

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Receiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage

Electricity Output

2

Heliostats

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Receiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage

Electricity Output

2

Heliostats

sCO2 turbine[Southwest Research

Institute]

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System ConfigurationFuel Production

HeliostatsReceiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage 2

78

CO2 & H2O Dissociation

Reactor

Fuel Production

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System ConfigurationFuel Production

Receiver

Power Conversion

Unit

Sloping Ground


Secondary Reflector

1

3

6

5

4

Storage 2

78

CO2 & H2O Dissociation

Reactor

Heliostats

Fuel Production

Syngas production from CO2 & H2O

[NCF & Weizmann]

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Compliance with the Fundamental Requirements

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5. Affordable cost

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5. Affordable cost

✓

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5. Affordable cost

✓

✓

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5. Affordable cost

✓

✓

✓

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5. Affordable cost

✓

✓

✓

✓

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5. Affordable cost

✓

✓

✓

✓

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5. Affordable cost – check efficiency and LEC

✓

✓

✓

✓

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Efficiency Comparison

SolarThermalSystems

LinearFresnel

Trough

SolarTower>20MWe

SolarTower~5-20MWe

SolarTower<5MWe

Dish-Concentrator

31%

30%

AchievableAnnualAvgerageSystemefficiency

18%

20%

18%

26%

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Efficiency Comparison

Each module of our system is 10-15 MWt (~3.0-4.7 MWe)

SolarThermalSystems

LinearFresnel

Trough

SolarTower>20MWe

SolarTower~5-20MWe

SolarTower<5MWe

Dish-Concentrator

31%

30%

AchievableAnnualAvgerageSystemefficiency

18%

20%

18%

26%

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0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

4.00% 5.00% 6.00% 7.00% 8.00% 9.00% 10.00%

NewS-TSysyem

PVw/oStorage

PVwithStorage

CC,[email protected]$/MMBtu


LEC($/MWh)

fcr

Direct Radiation Energy = 5.6 kWh/m2/day (2040 kWh/m2/year)

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0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

4.00% 5.00% 6.00% 7.00% 8.00% 9.00% 10.00%

NewS-TSysyem

PVw/oStorage

PVwithStorage



LEC($/MWh)

fcr


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0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

4.00% 5.00% 6.00% 7.00% 8.00% 9.00% 10.00%

NewS-TSysyem

PVw/oStorage

PVwithStorage



LEC($/MWh)

fcr


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0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

4.00% 5.00% 6.00% 7.00% 8.00% 9.00% 10.00%

NewS-TSysyem

PVw/oStorage

PVwithStorage



LEC($/MWh)

fcr


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0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

4.00% 5.00% 6.00% 7.00% 8.00% 9.00% 10.00%

NewS-TSysyem

PVw/oStorage

PVwithStorage



LEC($/MWh)

fcr

Direct Radiation Energy = 5.6 kWh/m2/day (2040 kWh/m2/year)Direct Radiation Energy = 6.8 kWh/m2/day (2500 kWh/m2/year)

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Levelized Fuel (Syngas) Cost

0

100

200

300

400

500

600

4.00% 5.00% 6.00% 7.00% 8.00% 9.00% 10.00%

LFC[$/ton]@5.6kWh/m2/day

LFC[$/ton]@6.8kWh/m2/day

LEC($/ton)

fcr

Direct Radiation Energy = 5.6 kWh/m2/day (2040 kWh/m2/year)Direct Radiation Energy = 6.8 kWh/m2/day (2500 kWh/m2/year)

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Development Status• The proposed process combines developments

by a group of collaborators working together and separately over 25 years.

• The main system components have been tested and proven on a small scale, but must still be,• designed for the operating conditions of the

proposed system• scaled up • integrated and operated together

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Main Conclusions1. The proposed solar power-generation system enables

• very large-scale installation

• Year-round, 24/7 power supply per demand

At competitive Levelized Energy Cost (LEC)

2. The system can be modified for syngas production from CO2 and water by the addition of a chemical reactor, with minor changes of other system components.

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Main Conclusions1. The proposed solar power-generation system enables

• very large-scale installation

• Year-round, 24/7 power supply per demand

At competitive Levelized Energy Cost (LEC)

2. The system can be modified for syngas production from CO2 and water by the addition of a chemical reactor, with minor changes of other system components.

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Last Comment…

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From talk at MIT on Oct. 2009

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The ‘Real World’ Problem of Solar Thermal

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The ‘Real World’ Problem of Solar Thermal • Facts:

– There are unprecedented opportunities for solar power “here and now”

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– Trough is the only mature solar technology

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• Developers are faced with few options:

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• Developers are faced with few options: – Grab the opportunity and build trough systems (low risk, short-

term payback)

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term payback) – Develop a new technology that can be cheaper than trough and

commercially ready in 1-2 years (medium risk, possibly longer payback)

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– Develop a breakthrough technology that can reach cost parity with conventional plants but takes 4-5 years to matures (high risk, long term payback)

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– Develop a breakthrough technology that can reach cost parity with conventional plants but takes 4-5 years to mature (high risk, long term payback)

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Our Approach

1. Strive for a long term, lowest cost solar power solution

2. Develop a storage solution

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Our Approach

1. Strive for a long term, lowest cost solar power solution

2. Develop a storage solution

3. Fast to market approach is acceptable if it leads to the long term solution

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Thank You!

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*** Supplement slides ***

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The price of Money (GE)Sep. 25, 2016

Short answer:GE are currently able to get loans for around 1% (less with a floating rate, more with a fixed rate).

Longer answer:GE floating rate note issued in 2007 pays interest (coupon) of 0.694%.GE note issued in 2015 (also floating rate) pays 0.287%In 2012 GE issued fixed rate 10 year debt for 2.7% (link)In 2015 GE issued fixed rate 12 year Euro denominated debt for 1.875% (link)In 2015 GE issued fixed rate 8 year Euro denominated debt for 1.25% (link)In 2015 GE issued fixed rate 7 year Euro denominated debt for 0.80% (link)

This page (http://quicktake.morningstar.com/stocknet/bonds.aspx?symbol=ge) lists many more GE bonds and has a nice graphic of yields and maturities. While these yields aren't interest rates paid by GE (GE pays more in general) they indicate the rates that the market is willing to accept for GE debt.

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The price of MoneyNuclear Power Plants

The modernization of Generation II and III Nuclear Reactors for power generation typically includes improved safety system and 60 years design life.

Generation II reactor designs generally had an original design life of 30 or 40 years. This date was set as the period over which loans taken out for the plant would be paid off.

However, many generation II reactor are being life-extended to 50 or 60 years, and a second life-extension to 80 years may also be economic in many cases.

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Annual fuel costs



Eelec,yr

Cinvest

CO&M

C fuel

Eelec,yr

fcr =kd 1+ kd( )N


(or Annuity Factor)

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Annual fuel costs



Eelec,yr

Cinvest

CO&M

C fuel

Eelec,yr

fcr =kd 1+ kd( )N


(or Annuity Factor)

HereweareonlyinterestedinthesolarLEC

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Cinvest

CO&M

fcr =kd 1+ kd( )N


(or Annuity Factor)


Esolar−elec,yr

Esolar−elec,yr

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Annual-averaged system efficiency



Cinvest

CO&M

Esolar−elec,yr


Esolar−elec,yr



∫

ηsys,yr−avg


tyear ,sun

∫

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Overall annual-averaged system efficiency



Cinvest

CO&M

Esolar−elec,yr


Esolar−elec,yr



∫

ηsys,yr−avg


tyear ,sun

∫

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LEC Reduction



∫

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LEC Reduction



∫

1. Select a site with good solar conditionsNot unique to any technology

129MITEISep2016

LEC Reduction



∫


2. Obtain favorable financing to minimize fcrNot unique to any technology

130MITEISep2016

LEC Reduction



∫



3. Lower production, installation and operation costsNot really unique to any technology

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LEC Reduction



∫





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LEC Reduction



∫




4. Increase the overall annual system efficiency. Increasing the collector area causes an increase in costs and generally does not reduce the LEC.

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LEC Reduction






∫

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LEC Reduction



∫


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LEC Reduction



∫


• It is the most effective way to decrease LEC.

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LEC Reduction



∫


• It is the most effective way to decrease LEC.• We must develop systems with a potential for

higher annual system efficiency than possible in present solar systems.

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The Difficult Issues of Solar Thermal

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The Fundamental Problem of Solar Thermal

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The Fundamental Problem of Solar Thermal • The the most efficient and lowest cost Heat Engines

are large – typically over 100MWe units

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• Whereas:– Optimum engine size for Parabolic Trough ~50-100MWe– Optimum engine size for Central Receiver <15MWe– Optimum engine size for parabolic dish ~0.1MWe

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• The optical efficiency is far better for small solar systems

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• The optical efficiency is far better for small solar systems

• Next Generation solar thermal systems must address this problem to reach cost parity with conventional power plants

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Optical Characteristics – Dish and Ideal Central Receiver

Parabolic Dish Concentrator

Fresnel Reflectors

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Optical Characteristics – Real Central Receiver

• Focal image increases by 1m per 100m distance due to sun-shape• Focal image increases further as the rays angle of attack increases with distance from tower• Heliostat spacings must increase with distance from target to avoid light blocking

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%

Total electricity demand and wind power input to the grid in the E.ON TSO area (Germany)


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A proposed energy conversion process for making solar ...energy.mit.edu/wp-content/uploads/2016/09/A-proposed-energy-conv… · MITEI Sep 2016 6 Fundamental Requirements 1. Use clean,