WIND AND SOLAR ENERGY LULLS: ENERGY STORAGE IN GERMANY

Germany has a goal to have almost all of its domestic electricity consumption from renewable sources by 2050. The Energiewende goals are:

 

Year

% RE of electricity

% RE of all primary energy consumption

2015

 30.8

14.7

2016

 32.7

14.8

2017

 35.1

15.2

2020

35

18.0

2030

50

 

2040

65

 

2050

80

60.0

 

Thus, about 20% of domestic electricity consumption could continue to be from fossil fuels, such as natural gas, in 2050.

 

Gross Electricity Generation: In 2016, gross electricity generation was 648.3 TWh, of which 460.0 TWh was from conventional generators and 188.2 TWh was from renewables, i.e., about 188.2/648.3 = 29% of gross electricity generation was from renewable sources, such as wind, solar, hydro, bio, etc. See table.

http://www.ag-energiebilanzen.de

 

German Electricity Generation, 2016

Electricity

Electricity

TWh

%

Soft coal (lignite)

150.0

23.1

Nuclear

84.6

13.1

Hard coal

111.5

17.2

Natural Gas

80.5

12.4

Mineral products

5.9

0.9

Other

27.5

4.2

Total Non-RE

460.0

71.0

Wind, onshore

65.0

10.0

Wind, offshore

12.4

1.9

Hydro

21.0

3.2

Biomass

45.6

7.0

Solar

38.2

5.9

Household waste

6.0

0.9

Total RE

188.2

29.0

Total generation

648.2

100.0

Wind plus solar was 78.6 + 38.1 = 116.7 TWh. On an annual basis, wind and solar (stochastic sources) was 116.7/648.3 = 18% of electricity generation.

 

In 2016, net electricity consumption was gross generation (648.3), less net exports (53.7), less transmission and distribution (30), less pumped storage and misc. (19.4), or about 545.2 TWh at user meters. 

Net electricity consumption = Industry 247 + Transport 11 + Households 129 + Trade and Services 139 = 526 TWh.

https://www.cleanenergywire.org/factsheets/germanys-energy-consumpt...

Electricity in 2050: After implementation of heat pumps for almost all buildings and replacing almost all fossil fuel vehicles with plug-in hybrids and plug-in all-electric vehicles, electricity consumption would significantly increase.

Alternatives for Energy Storage to Cover Wind and Solar Lulls

When Germany has one of its sunny and windy days, RE proponents usually mention Germany obtained a large percentage of its electricity generation from renewables. They usually do not mention “for up to about one hour around noontime”. RE proponents often say, wind and solar can generate almost all electricity. All that is needed is more build-outs and energy storage. 

 

With increased future reliance on weather-dependent wind and solar electricity, it would be useful to determine the required energy storage system capacity, GWh, if nuclear and fossil plants were closed in the near future. This article shows what might be required during two consecutive wind and solar lulls in December 2050, as occurred in December 2016.

 

Below is a comparison of the following alternatives:

 

Alt. No. 1: The same lulls in December 2050, with 50 GW of CCGT generators.

Alt. No. 2: The same lulls in December 2050, with 75 GW of nuclear and 50 GW of CCGT generators.

 

Existing Conditions, Wind and Solar Lulls in December 2016: At present, during periods of almost no wind and little sunshine, conventional generators provide the electricity to meet the demand. Such was the situation, when high-pressure winter weather caused extremely low outputs of wind and solar electricity in Germany and surrounding countries during 2 periods in December 2016.

 

The above figure shows:

 

- Such weather events can persist for several days. The first lull lasted about 100 hours, the second about 50 hours.

 

- Germany exported electricity during almost all hours of the 16-day period. Those exports likely went to Denmark, as it relies on imports from Norway, Germany, the Netherlands, etc., during its wind lulls. Germany exported 85 TWh and imported 34 TWh, during 2015.

 

The power from different sources quoted in the Agora article are summarized in the table.

 

Lull, 3-6 Dec 2016

GW

Installed GW

Demand

74.5

 

Supply

 

 

Conventional*

64.4

 

Hydro, bio, etc.

8.0

 

Solar

0.7

41.0

Onshore wind

1.0

44.5

Offshore wind

0.4

3.3

 

* Conventional includes fossil, nuclear, imports and exports.

Summary of Capital Costs of Alternatives 1 and 2

At a cost of about $0.45 trillion for nuclear plants (with almost no CO2 emissions) and $0.08 trillion for CCGT plants, implementing the Energiewende would be about 5.47 - 1.44 = $4.03 trillion less costly, plus the environmental adversities of wind turbines, solar panels and associated transmission lines would be significantly less intrusive.

 

German electricity generation would be about 85% without CO2 emissions by 2050; bioelectricity has CO2 emissions, which are partially reabsorbed over periods of 50 - 100 years.

Alternative No. 1, With CCGT, Without Nuclear

 

2050

Times

 GW in 2050

 $trillion

CCGT

 

50.0

0.08

Solar

 6.5

266.5

0.67

Onshore wind

6.5

289.0

0.64

Offshore wind

6.5

21.3

0.09

Storage, distributed

 

 

3.99

Total

 

 

5.47

 

Alternative No. 2, With CCGT and Nuclear

 

2050

Times

GW in 2050

$trillion

Nuclear

 

75.0

0.45

CCGT

 

50.0

0.08

Solar

2.5

102.5

 0.26

Onshore wind

2.5

111.2

0.24

Offshore wind

 2.5

8.2

0.03

Storage, distributed

 

 

0.38

Total

 

 

1.44

Alt. No. 1, Wind and Solar Lulls, Plus 50 GW of CCGT Generation in December 2050

RE proponents claim wind, solar, hydro, bio, etc., could generate almost all electricity, and fossil fuel and nuclear generators are not needed. However, if fossil fuel and nuclear generators were closed down and wind and solar were minimal, hydro, bio, etc., whether in Germany or abroad, would not be able to meet Germany’s electrical demand without massive, bulk energy storage systems.

 

For this alternative, we assume Germany would:

 

- Consume the same quantity of energy in 2050, as in 2016, i.e., increased due to population and gross product growth, but reduced due to energy efficiency.

- Increase its gross electricity generation from 652 TWh in 2015 to 1118 TWh in 2050, due to heat pumps and electric vehicles.

- Have 6.5 times the installed capacity, MW, of wind and solar systems and associated transmission, in 2050.

- Experience the same wind and solar lulls in December 2050, as in December 2016.

 

The Agora graph shows, the 2016 average demand was about 74.5 GW from the 3rd to 7th of December 2016. We assume the 2050 demand would be about 127.7 GW. A small part of the demand could be decreased by means of demand management; those procedures were not included in the analysis.

 

Electricity generation would be about 1118 TWh (3.062 TWh/d) in 2050, of which 855 TWh from RE and 263 TWh from CCGT plants. The CCGTs plants would have CO2/kWh emissions less than half of coal plants. Electricity generation would be about 85% CO2-free.

 

Below is the 2050 power balance for the first wind and solar lull. This power balance would produce about 3.065 TWh/d.

 

1st Lull, Dec 2050

 

Demand GW

Installed GW

Demand

 

127.7

 

Supply

 

 

 

Storage*

 

62.0

 

CCGT

CF 0.80

40.0

 

Hydro, bio, etc.

 

12.0

 

Solar

 6.5 x 0.7

4.6

6.5 x 41.0

Onshore wind

6.5 x 1.0

6.5

6.5 x 44.5

Offshore wind

6.5 x 0.4

2.6

6.5 x 3.3

 

* Storage includes imports and exports

Storage System Capacity and Cost: The storage systems would need to be capable to deliver about (100-h lull + 50-h lull) x 62.0 GW = 9.3 TWh delivered as AC. Imports and exports would be minimal, as nearby countries also would have wind and solar lulls.

 

The storage system would need to have a capacity of about 1.5 x 9.3 = 15.95 TWh delivered as AC, because we cannot assume the batteries are fully charged at the start of the lull.

 

Turnkey Capital Cost of Battery Systems: The capital cost would be 15.95 x 1,000,000,000 kWh x $250/kWh = $3988 billion. They would be distributed throughout Germany. A significant percentage of this capital cost would be repeated every 15 - 20 years to replace the batteries.

 

The battery systems would be charged:

- With variable solar energy during peak generating hours (about 9 am to 3 pm) and would discharge energy, as needed to meet demand, during other hours, on a daily basis.

- With variable wind energy and would discharge energy, as needed to meet demand, during all hours of the year.

- By the other generators (hydro, bio, refuse, etc.), as needed, during all hours of the year.

 

NOTE: The Agora graph shows, the second wind and solar lull occurred a few days later. That means, either there must be:

 

- Enough electricity generation (wind, solar, hydro, refuse, etc.) to recharge the battery systems in a few days, including charging losses of about 10%, plus serve the demand (a very tall order), or

- Even greater battery storage capacity to serve demand during the 2nd lull, or

- A significant, not weather-dependent, gas-fired, CCGT plant capacity, MW.

- The safe approach would be to have available the additional storage capacity, and the CCGTs.

NOTE: Germany policymakers are beginning to realize expensive, bulk energy storage systems are not an economically viable option in the near future. Accordingly, Germany will place:

 

- Up to 4400 MW of plants in “capacity reserve” to ensure the security of power supply in case of unforeseeable and extreme conditions. Payments for such back-up services were 67 million euro and 168 million euro in 2014 and 2015, respectively, and are estimated to increase to about 260 million euro per year.

- Up to 2700 MW of lignite plants in “security reserve” in the case of long-lasting, extreme weather events. The “security reserve” will cost an estimated 230 million euros per year, on average, and will last for about seven years.

 

NOTE: Germany RE curtailments, mostly wind, likely will significantly increase, as more wind and solar build-outs are added in future years. See table.

 

Year

TWh

$million

2012

 0.38

23

2013

 0.55

33

2014

 1.58

 94

2015

 2.69

160

 

Alt. No. 2, Wind and Solar Lulls, Plus 75 GW of Nuclear and 50 GW of CCGT Generation in December 2050

Germany may change its collective mind regarding nuclear energy, once the people realize the cost and environmental impacts of the required wind, solar and transmissions system build-outs by 2050, as shown in Alternative No. 1.

 

The nuclear plants would have standard 1100 MW units, which reduces turnkey costs. The plants would be a mix of base-loaded and load-following plants, similar to France. Hydro, bio, etc. plants would be operated as at present.

 

Electricity generation would be 1,118 TWh by 2050, of which 296 TWh from RE, 559 TWh from nuclear, and 263 TWh from CCGT plants. Electricity generation would be about 85% CO2-free.

 

NOTE: In France, nuclear plants generate about 75% of total electricity. France has among the lowest household electric rates in Europe and Germany has the second highest, about 30 eurocent/kWh, after Denmark, about 31 eurocent/kWh, as shown by above graph.

 

Below is the 2050 power balance for the first wind and solar lull. This power balance would produce about 3.065 TWh/d.

 

Period

Dec 2050

GW

Installed GW

Demand

 

127.7

 

Supply

 

 

 

Storage*

 

6.7

 

Nuclear

 

63.8

 

CCGT

 

40.0

 

Hydro, bio, etc.

 

12.0

 

Solar

 2.5 x 0.7

1.8

2.5 x 41.0

Onshore wind

2.5 x 1.0

2.5

2.5 x 44.5

Offshore wind

2.5 x 0.4

1.0

2.5 x 3.3

 

* Storage includes imports and exports

The storage systems would need to be capable to deliver about (100-h lull + 50-h lull) x 6.7 GW = 1.005 TWh delivered as AC. Imports and exports would be minimal, as nearby countries also would have wind and solar lulls.

 

The storage system would need to have a capacity of about 1.5 x 1.005 = 1.51 TWh delivered as AC, because we cannot assume the batteries are fully charged at the start of the lull.

 

Turnkey Capital Cost of Battery Systems: The capital cost would be 1.51 x 1,000,000,000 kWh x $250/kWh = $378 billion. They would be distributed throughout Germany. A significant percentage of this capital cost would be repeated every 15 - 20 years to replace the batteries.

ALTERNATIVE ENERGY STORAGE SYSTEMS

 

Below are listed a few alternative ways of dealing not only with multi-day wind and solar lulls, but also with storing a variable wind and solar energy supply to serve demand 24/7/365, year after year.

Pumped Hydro Plants to Shift Seasonal Energy Variations: According to a study titled “Buffering Volatility: A Study on the Limits of Germany’s Energy Revolution”:

 

In 2014,

- If all of Germany’s wind and solar energy had been stored, Germany would have required about 11.29 TWh of pumped hydro storage, or 11.29/0.038 = 297 times Germany’s 2014 PHS of 0.038 TWh.

- If all nuclear plants had been closed and replaced by W&S (resulting in 2 times 2014 W&S), about 15.25 TWh of PHS would have been required, or 15.25/0.038 = 401 times Germany's 2014 PHS capacity.

- If all fossil plants had been closed and replaced by W&S (resulting in 3.5 times 2014 W&S), about 26.6 TWh of PHS would have been required, or 26.6/0.038 = 706 times Germany’s 2014 PHS capacity.

 

In 2050,

- Alternative no. 1, with 6.5 times W&S, would require about 69.9 TWh of PHS, or 68.9/0.038 = 1829 times Germany’s 2014 PHS capacity.

- Alternative no. 2, with 2.5 times W&S, 18.3/0.038 = 486 times Germany’s 2014 PHS capacity.

 

Producing Methane Syngas by Electrolysis: Wind and solar electricity can be used to split water into hydrogen and oxygen by means of electrolysis. The hydrogen can be converted to methane, CH4, and stored in underground caverns. At present, process development is conducted in various power-to-gas, P2G, pilot plants.

 

Producing hydrogen from electrolysis, with electricity at 5 cents/kWh, will cost $28/million Btu (HHV), slightly less than two times the cost of hydrogen from natural gas.

 

NOTE: The cost of hydrogen production from electricity is a linear function of electricity costs, so electricity at 10 c/kWh means hydrogen will cost $56/million Btu (HHV), or 56/0.845 = $66.3/million Btu (LHV)*.

* LHV/HHV = 0.845

German wind and solar generation cost is about 10 c/kWh. 1 million Btu of methane, LHV, to a CCGT would produce 500000 Btu of electricity, or 146 kWh for $66.30, or 45.4 c/kWh.

 

The methane has to be piped to a storage reservoir, stored, then discharged, then piped to CCGTs, for a loss of about 20%, so the cost becomes 45.4 c/kWh/0.8 = 56.7 c/kWh, plus utility mark-up and taxes, fees and surcharges.

Very significant overbuilding of wind and solar would be required to ensure adequate storage for seasonal shifting and multi-day wind and solar lulls.

  

Methane Syngas to Cover Wind and Solar Lulls in 2050: In 2050, during the 2 lulls, Germany would need to generate about (3 TWh/d x d/24 h x 150 h = 18.75 TWh.

The generators of Alternative no. 1 would produce about 65650 MW x 150 h = 9.85 TWh, for a shortfall of 8.90 TWh, which has to be made up with syngas-fired CCGTs.

The required capacity of the CCGTs would be 8.9 TWh/(150 h x 0.85 CF) = 69,824 MW.

The required syngas would be 8.9 TWh/0.5 efficiency = 17.8 TWh, LLV, which is equivalent to 60.7 x (1/0.845) = 71.8 billion cubic feet HHV. 

 

At a maximum operating pressure of about 100 bar (1470 psig) the underground volume would be about 0.718 bcf. The quantity of stored syngas would be double that, or about 150 TWh, to provide adequate operating cushion.

 

This approach may not be economically attractive with a CF of about 0.20 for wind energy in Germany, and a P2G a-to-z process efficiency of 60%, and pumping into storage at 90%, and discharging from storage at 90%, and burning the gas in a CCGT at 50%.

German Seasonal Energy Shifting: Below are estimates of the storage that would have been required in 2014:

 

- If all of Germany’s wind and solar energy had been stored/smoothed, about 11.29 TWh.

- If all nuclear plants had been closed and replaced by W&S (resulting in 2 times 2014 W&S), about 15.25 TWh.

- If all fossil plants had been closed and replaced by W&S (resulting in 3.5 times 2014 W&S), about 26.6 TWh.

 

In 2050, at 6.5 times W&S, about 69.9 TWh would be required. Note: The US 2016 gross electricity generation was 4000/648 = 6.2 times Germany’s gross generation.

 

The seasonal storage quantities would need to be increased by up to 20% for round trip losses, in case of pumped hydro storage. In case of syngas storage, to generate the above 69.9 TWh, the required gas input to CCGTs would need to be 69.9 TWh/(CCGT efficiency, 0.55 x 0.845 LHV/HHV) = 150.4 TWh, and the storage caverns would need to hold at least 300 TWh for operational purposes. 

NOTE: The energy loss to produce the syngas, compressing and piping it into storage caverns, discharging it from the caverns, recompressing and piping it to CCGTs, almost all of it performed with wind and solar energy, was omitted to reduce complication of the analysis.

Losses Due to Seasonal Storage Requirements: At present, any energy sent into storage is less than 1% of gross electricity generation, and associated losses are minimal. This would not be the case in 2050, when much greater storage flows and storage capacity, TWh, would be required.

 

In 2050, all wind and solar electricity would need to be sent into storage throughout the year to ensure adequate electricity supply, 24/7/365, year after year, which involves a total loss of 1.02, self-use x 1.07 T&D x 1.1, charging x 1.1 discharging = 32%, i.e., wind and solar capacity, MW, plus associated grid expansions, would need to be 32% greater to offset these losses. The required turnkey capital costs were NOT included in above Summary of Capital Costs of Alternatives 1 and 2.

APPENDIX 1

Renewable Generation in Germany and Texas: The Jacobson study is for 100% of US primary energy from wind, solar, and miscellaneous (mostly hydro, no nuclear and no biomass), by 2050. See URL for evaluation of the study.

http://www.windtaskforce.org/profiles/blogs/review-of-the-100-re-by...

 

A recent study by Peter Davies is for 100% of Texas electricity generation from wind and solar by 2050. The primary energy of electricity (the energy fed to power plants, i.e., before conversion) is only about 35% of Texas primary energy. It would be much more difficult to have 100% of Texas primary energy from wind and solar.

 

https://judithcurry.com/2017/05/14/electricity-in-texas-is-100-rene...

https://judithcurry.com/2017/08/06/electricity-in-texas-part-ii-the...

 

Texas has high CFs for wind and 2-axis PV solar. Texas already has more than 20,000 MW of wind. Texas may achieve 80% of electricity generation from renewables wind sooner than Germany, and at much lower cost. Much depends on how much energy storage is needed in Texas.

 

Germany has poor CFs for wind and solar, almost no solar generation in winter, and long wind lulls, which means its storage requirements, relative to its electricity generation, would be much greater than Texas. See URLs.

 

http://www.windtaskforce.org/profiles/blogs/wind-and-solar-energy-l...

http://beyondthesuperficial.com/blog/response-to-andrew-rogers-texa...

APPENDIX 2

CO2 From Gross Electricity Generation

Germany generated 648.3 TWh and had about 560 g of CO2eq/kWh in 2016.

France generated 530 TWh and had about 58 g of CO2eq/kWh in 2016.

 

Germany’s electricity generation had 560/58 = 9.7 times more CO2 emissions/kWh than France, which gets about 80% of its electricity from nuclear.

 

Germany has been replacing nuclear (near-zero CO2) with mostly coal and natural gas, and some solar and wind; regarding CO2, bio energy does not count, as it is assumed to emit no CO2.

Germany Not Reaching CO2eq Goals: Germany’s CO2eq emissions (all sources) in 2016 were about the same as in 2009.

Germany’s consumption of electricity from renewables has increased from 30.8%, 32.7%, and 35.1% in the first half of 2015, 2016, and 2017, respectively. But regarding the consumption of thermal energy for buildings, industry and commerce, and fuels for transportation, there has been so little change that the overall energy consumption from renewables has increased from 14.7%, 14.8% and 15.2% in the first half of 2015, 2016 and 2017, respectively. Germany will not meet its 18% goal in 2020.

 

http://www.dw.com/en/germanys-renewable-energy-use-rises-but-only-j...

https://www.carbonbrief.org/how-germany-generates-its-electricity

 

The electricity sector contributes only about 45% of Germany’s total emissions. The 100% decarbonizing of the electricity sector, which is already about 45% decarbonized (if we add nuclear) would reduce total emissions by about another 25%. Yet Germany’s efforts to decrease emissions continue to concentrate on the electricity sector.

 

German households paid a minimum of about 8 x 25 billion euro = 200 billion euro in taxes, fees and surcharges on their electric bills to gain zero CO2eq emission reduction in the electrical sector during the 2009 - 2016 period.

 

Germany, a big industrial nation, will not meet its CO2eq goals for 2020, 2030, 2040 and 2050. See table.

 

https://www.cleanenergywire.org/news/german-carbon-emissions-rise-2...

http://www.ag-energiebilanzen.de/4-1-Home.html

http://revue-arguments.com/articles/index.php?id=76

 

Year

All sources CO2eq

 Reduction below 1990

Electricity CO2eq

 

million Mt

 %

million Mt

1990 actual

1251

 

427

2009 actual

907

 

344

2016 actual

906

 

345

2020 target

 751

  40

 

2030 target

 563

 55

 

2040 target

375

30

 

2050 target

250

20

 

APPENDIX 3

More Wind and Solar, Higher Household Electric Rates: Denmark and Germany implementing higher renewable energy percentages has led to higher household electric rates. The same would happen in Vermont. German household electric rates are the second highest in Europe, about 28.69 eurocent/kWh in 2015; Denmark is the leader with about 30 eurocent/kWh, Ireland is at 25 c/kWh, Spain 24 c/kWh, France, about 80% nuclear generation, 17 c/kWh. Click on URLs to see revealing graphs.

 

https://www.bdew.de/internet.nsf/id/DC9ABD3F2D97604DC1257F42002E507...

http://euanmearns.com/an-update-on-the-energiewende/

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