Renewable EnergyProf. David Elliott

The Open University

Sustainable energyWe need to use energy in a way that

1. Does not rely on scarce fuel resources

2. Can be relied on into the far future

3. Does not have major environmental impacts

As an interim measure we can reduce eco-impacts by :

*Using energy from existing power plants moreefficiently - e.g. insulating buildings to avoid energy losses

*Developing cleaner more efficient power plants -e.g combined heat and power /cogeneration plants, and using lower carbon fuels

Long term sustainability

However also we have to begin a full scale switch over to non fossil energy sources.

Nuclear fission might play a role, but relies on finite fuel sources. Nuclear fusion also has resource limits- although much longer-term

By contrast the renewable energy options, solar, wind, wave, tidal, hydro, biomass, geothermal etc won’t ever run out.

Global renewable energy resources

Incident solar: 90,000TW p.a. continuous

Potentially available resource:

Solar 1000 TW

Wind 10TW

Hydro 2TW

Wave 1TW

Tidal 0.1TW Jackson T, Energy Policy 20(9) 861-83

Current global energy generation-13TW

Hydro electric plants generate

about 18% of the worlds electricity-

from 740GW installed globally

Traditional biomass is a major source of heat

Modern Biomass can be more efficient and be used to generate

electricity

A huge resource- forestry wastes and specially grown energy crops

Carbon Neutral since-

Emissions form combustion = Absorption during growth

Solar heat Collectors-

simple radiator-like

unitsCut annual water

/space heating fuel

bills by 50%

Evacuated tube solar collector- more efficient but more expensive

Total world installed solar heat capacity= 120GW (Thermal)

Electricity- PV solar energy

10GW peak

installed

globally

Solar PV Tiles

..and prices

are falling.

But PV is still

expensive:

£5,000-10,000 per house

The technology is

improving...

Nano solar

PV

Solar

Concentrating Solar Power (CSP)

Focused solar ‘Power Tower’

3 GW(e) of new capacity announced globally so far

Windturbines

Now 120 Gigawatt in operation around the world

Offshore

wind, tidal,

wave- the

UK has the

world’s best

resources

La Rance Barrage, Brittany, 240 MW

Geothermal energy

10GW of electricity generation globally,plus ~15GW(thermal) heat production

Renewables - current global

contributionsOver 1TW - 18% of global electricity, With biomass, 18% of global energy

Renewable electricity generation capacity 1,010GW in 2007, including 740GW of hydro, supplying 18.4% of total world electricity.

Nuclear was at 370GW supplying about 15% of total world electricity.

Non-hydro renewable generation capacity was 5% of total world electricity generation capacity, supplying 3.4% of total world electricity.

Renewables supplied 18% of total world energy consumption

Renewable energy share in final global energy consumption in 2006www.ren21.net/globalstatusreport/default.asp

Scale-little or large?

Economies of Scale* Physical scale- big plants are more economic e.g. doubling from 300 to 600 MW, adds a few percent to efficiency

* Market scale- bigger volume, more sales, lower unit cost

* Production scale- more units, lower costs per unit

Small is beautiful?

Small generators can be nearer loads-less transmission losses

Can save up to 10% for electricity …Also more cost effective for heat

production/ distribution

Micro generation Low Carbon Building Programme

Renewables Low Carbon

Micro- wind Micro CHP

Electricity

PV solar

Electricity

Stirling Engines

Fuel Cells -gas fired

Solar Heating Others :

Electric powered

Others : Biomass for heat /electricity Heat Pumps

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The energy available from the wind is the square of the blade diameter.

So a machine with blade diameter ten times that of a micro device, can generate 100 times more power than the micro device - 10 times more than 10 micro devices.

The energy in the wind is also the cube of the wind speed.

Larger machines are likely to be in much winder areas. Just doubling the wind speed from 4m/s (poor inner city site) to 8m/s (good elevated rural site) would yield 8 times more wind

1-2MW

1-2kW

Micro wind in the city

' In many urban areas they are unlikely to pay back either their carbon emissions or the home owner's costs for installation and maintenance'.

Building Research Establishment Dec 2007

Small is not always beautiful

‘The economics of all distributed energy technologies

improve with increasing scale, leading to lower cost

energy and lower cost carbon savings and justifying

efforts for community energy projects

It is only when action occurs at scales above 50

households, and ideally at or above the 500 household

level, that significant carbon savings become

available.’

‘Power in Numbers’ Energy Saving Trust 2008

‘Power in

Numbers’,

EST 2008

‘Where

possible,

communities

should be

encouraged to

work together

to deploy the

largest possible

turbines, as

opposed to

series of

individual

installations’.

COMMUNITY SCALE

BIG ENOUGH TO BE TECHNOLOGICALLY AND ECONOMICALLY EFFICIENT

SMALL ENOUGH TO BE LOCALLY OWNED OR CONTROLLED

and local projects can help in local economic and social

regeneration

Locally owned wind project in Wales

COMMUNITY TECHNOLOGY

With proper support, the Energy

Saving Trusts see renewable distributed

generation (heat and power) supplying

of the order of 130TWh per year from

individual/small communities or 175TWh

per year under large scale community

Action by 2020.

These figures represent 7.5% and 10%

of total annual UK energy demands

respectively and could save up to

35% of the annual household CO2

emissions.

EST ‘Power in Numbers’ 2008

Ownership of Onshore wind power in UK, Germany, Denmark and The Netherlands by

Per Cent Capacity in 2004

Type of owner UK Germany Denmark Netherlands

Utilities/ 98 55 12 60

corporate

Farmers 1 35 63 34

Co-ops 0.4 10 25 6

.

Middlegrunden wind farm off Copenhagen :

50%owned by a local residents coop.

Limits to urban autonomyThe Climate Change Action Plan produced by Mayor of London Ken Livingstone sets a target to move a quarter of London’s energy supply off the National Grid and on to more efficient, local energy systems by 2025.

“We cannot switch all our energy over to renewable energy just yet, as the renewable energy produced today cannot meet all of London’s energy demand’

London Strategy Document.

An earlier proposal included an overall target of obtaining 14% of London’s electricity from renewables by 2010, 4% from internal sources, the rest being imported.

Potential % of overall UK electricity supply in 2050

Onshore wind 8-11%

Offshore wind 18-23%

Wave/Tidal 12-14%

Biomass 9-11%

PV solar 6-8%

TOTAL 53-67%

Based on overall likely level of supply of 400-500 TWh in 2050

Source: DTI/Carbon Trust ‘Renewables Innovation Review’ 2004

Biomass

Biomass fuel cycle

Biomass resource

• ‘800 exajoules (EJ) of energy could be available from energy farming on current agricultural land, without conflicting with the worlds food supplies-about twice total world energy use. And the potential, with forest and grasslands also included, is much larger- maybe 4500 EJ of annual primary production, or 2900EJ of annual bioenergy potential’.

• The Biomass Assessment Handbook, edited by Frank Rosillo-Calle et al Earthscan

Biomass wood chip for

combustion

Sources-energy crops, forestry wastes.

Biogas from Anaerobic

Digestion -biomethane Sources: Farm wastes,

land fill gas, sewage gas

Biomass combustion plant

E.ON’s 44MW Stevens Croft Plant, near Lockerbie

Land use constraints

Hydro

Quebec

Biogas Resource potentials

50% of UK domestic residential heat requirements could be met by biogas by 2020-

National Grid, 2009

‘Biogas can replace natural gas imports into the EU by 2020’ Study for the German

Greens,2008 http://biopact.com/2008/01/report-biogas-

can-replace-all-eu.html

Algal Biomass

MIT - algal

capture of CO2

on its 20MW

cogeneration

plant

Algae- based biofuels

could replace 12% of

annual jet fuel

consumption and around

6% of road transport

diesel worldwide by

2030- Carbon Trust, 2008.

Some

species can

double their

biomass

every 3-4

days

Hydro Quebec

Wind power

Wind power potential

The Global Wind Energy Council (GWEC) predicts that in 2013 global wind generating capacity will stand at 332 GW, with 118GW in the EU, 85GW in N America and 117GW in Asia.

Up from 120 GW globally at the end of 2008.

‘Wind power net capacity additions over the last ten years (1998-

2007) have showed a mean growth rate of 30.4% per year,

corresponding to a doubling of net additions every 2 years’

Energy Watch, Germany www.energywatchgroup.org

Offshore wind-150GW from the North sea?

Airtricity North Sea Supergird -linking in off-shore wind farms

10GW initial stage now planned

Airtricity Supergrid

Euro Grid

The European Commissions new

Economic Recovery Plan (Feb. 2009)

includes 100 million euros (£93m) for a

grid link between the Republic of Ireland

and Wales to help renewables generators

in Ireland access the UK energy market.

And around 150 million euros (£139m) for

early work on a possible North Sea grid.

Europa GridNorwegian owned Transmission company Imera Power has announced plans to build undersea electricity grids in both the Atlantic and the North Sea.

The Dublin-based company said its plan for a large grid of subsea AC and DC cables could become the "foundation" for a pan-European offshore electricity network.

It is looking for 100m euros for the first stage. Source: NewEnergyFocus.com 3/2/09

The recently formed British company Mainstream

Renewables, plans to create a Supernode,

consisting of two interconnected offshore wind farms

one British, one German, with a backup connection

supplying Norwegian hydro, which it hopes to

complete in 2015.

This demonstration project

would then expand, and link

to similar schemes elsewhere

e.g in the Mediterranean.

New Scientist, 12 March 2009

EU Renewables Directive 2008

A new Guarantees of Origin trading system can be used

to trade electricity and heat/cooling -in 1MWh units -

between EU countries, for projects over 5MW.

Imported electricity, produced from renewable energy

sources outside the Community, may also count towards

EU Member States' targets, again using a system of

guarantees of origin.

But limits may be imported on how much can be imported-

this is still being negotiated .

JI and CDM Renewables and energy efficiency projects

Under the proposed next EU ETS (2013-2020), EU Member States may also use emission credits generated by projects outside the EU, via either:

* The Joint Implementation (JI) mechanism - covering projects carried out in countries with an emissions reduction target under the Protocol

* The Clean Development Mechanism (CDM) - for projects undertaken in developing countries.

But only credits from project types which were accepted by all Member States during the 2008-12 period will be eligible for use.

Also, the credits from CDM projects can only make up 3% of 2005 emissions of any importing EU country.

New Europe

Central and Eastern Europe: Renewable Potentials in the EU

MW(e) by 2020 Wind Geothermal Biomass

Hydro Total

Bulgaria 3,400 200 3,371 1,070 8,041 Czech Rep. 2,200 0 819 285 3,304 Estonia 500 0 248 0 748 Hungary 500 0 983 357 1,840 Latvia 550 0 325 428 1,303 Lithuania 500 0 318 214 1,032 Poland 4,0000 4,160 999 9,159 Romania 3,000 15 1,919 2,568 7,502 Slovakia 250 0 273 499 1,023 Slovenia

Central and Eastern Europe: Renewable Potentials outside the EU MW(e) by 2020 Wind Geothermal

Biomass Hydro TotalAlbania 50 0 625 1,070 1,745Armenia 400 0 89571 1,060Azerbaijan 1,500 0 218 1,142 2,860Belarus 200 0 996 214 1,410Bosnia/Herzegovina 50 1 79 1,712 1,843Croatia 1,000 48 575 642 2,265Georgia 2,300 15 149 4,852 7,315Kazakhstan 8,000 12 1,149 4,424 13,585Kyrgyzstan 1,500 0 166 7,063 8,729 Macedonia 50 0 89 428 567 Moldova 500 0 154 71

From Black and Veatch survey for EBRD reported in Renewable Energy 2007-08WREN

Not on their list- Turkey, with reportedly a 10GW wind potential and large

Expected turbine output for wide-area wind energy deployment in distant regions of high wind yield

Country Potential rated Power Potential production

[GW] [TWh/a]

Northern Russia andNorth-western Siberia 350 1100North-western AfricaSouthern Morrocco 120 400Mauritinia 105 320

EU-ME-NA grid network with CSP solar

in desert areas proving 15 % of energy

Concentrating

Solar Power

Concentrating Solar Power (CSP)

Focused solar ‘Power Tower’

Molten salt heat store for continued overnight operation

Concentrating Solar

Power5.8GW by 2012 www.emerging-energy.com

USA Major existing and planned projects in the USA- maybe 1GW by 2012

Spain Several existing projects - around 1GW expected by 2012

North Africa Major projects underway or planned in Morocco, Egypt, Algeria- maybe 1GW by 2012

Middle East Jordon, UAE, Iran, Israel- maybe 1GW by 2012

China 50MW project planned, maybe 1GW by 2020.

Pros CSP/HVDC EU links

Why not make use of solar where it is most intense- with molten salt heat

stores for overnight

Transmission losses low with HVDC links

Builds positive trading links with poor areas

Cons

Expensive and invasive- new grid links across the EU. Which might attract

terrorists

Solar energy available on your roof- why collect it from far away?

Could be an exploitative relation with desert countries

Just swopping reliance on imported oil and gas for imported solar electricity-

North could be held to ransom by the South!

Shouldn’t we sort our own house out first? Won’t this be used an excuse not

to do so?

HVDC grid links already planned for CSP from Africa

Wave and

Tidal power

Wave energy…

Waveplane Denmark

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MCT’s Seaflow tidal turbine concept

Tidal current turbines

MCT SeaGen 1.2 MW

Stangford NarrowsNarrows

Open Centre Tidal Turbine

ྟ

The Open Centre

Turbine has a slow-

moving self-

contained rotor, with

just one moving part

and no seals. A

solid state

permanent magnet

generator is

encapsulated within

the outer rim,

minimising

maintenance

requirements

Open Hydro Group Ltd, Ireland

ຕ

On test at EMEC in Scotland

and versions to be installed off

Alderney

ROTECH’s ‘Lunar Energy’ shrouded rotor

Channel Isles Region - Relative Timing of Peak Tide Velocity(24 hours - spring tide conditions - 6 minute resolution)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1 9 17 25 33 41 49 57 65 73 81 89 97 105 113 121 129 137 145 153 161 169 177 185 193 201 209 217 225 233 241

Time (24 hours)

Tid

al

Cu

rren

t V

elo

cit

y -

ms-1

Casquets GuerseyBigRussel GuerseyNorthWest NorthEastJersey RaceOfAlderney

Severn Barrage8.6GW

Severn Tidal Fence

1.3GW

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.Tidal Lagoon

Big stuff- new review of Severn options > 1GW

environmentally very invasive, inflexibleLunar cycles mean that regularly you will get

8.6GW when no demand, nothing when demand high. Overall means that you will only save 0.92% of UK

emissions by sometime after 2020- for £15bn. Pumped storage for Hinkley?

Lagoons- smaller, less impact, more

flexibleMay cost less, but as yet not tested

Tidal current turbines- small,

modular, small impacts, very flexible.

Large numbers distributed around the coast would all fire off four times each 24 hours at

different tidal peak times, to give continuous output from the network as a whole.

Ocean Current Power Farm Projects in S.Korea

Others:Shiwah area, 254MW planned for 2010

Uldolmog 100MW 2010Wando 300MW by 2015

Global Potentials

Shell Scenario 1995

Sustained Growth

Energy Watch ‘high’ scenario- 4,45GW of (non hydro) renewables globally by

2030-

30% share of final total energy demand,

62% of global electricity (Energy

Phase-out of fossil fuels

by 2050 and nuclear

power by 2025, leading to

33% reductions of

greenhouse gases by

2020 and 100% by 2050.

INforSE visions

UK government plan for energy reductions DECC 2009

Reductions in Per Capita Energy Consumption in the Different Sectors of

EU15 by 2050

0

500

1000

1500

2000

2500

3000

3500

4000

1990 2000 2010 2020 2030 2040 2050

Jahr

W/c

ap

Transport

Agriculture

Commercial

Households

Industry

Source: LTI Research Group 1998

Sustainable Energy Supply Scenario EU15 (2050)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1990 2000 2010 2020 2030 2040 2050

Year

W/c

ap

Coal Mineral oil Natural gas Nuclear energy Biomass PV

Solar thermal el. Solar thermal heat Wind energy Hydro power Heat pumps

Source: LTI Research Group 1998

Development of Renewable Energy Sources in the

EU15 Scenario Until 2050

0

200

400

600

800

1000

1200

1400

1600

1800

1990 2000 2010 2020 2030 2040 2050

Year

W/c

ap

Biomass PV Solar thermal el. Solar thermal heat Wind energy Hydro power Heat pumps

Source: LTI Research Group 1998

Germany- 23 GW of wind, 2GW PVIn 2008 it got 14.2% of its electricity, and 8.6% of its final

energy from renewables.

Target: 30% of electricity by 2020

USA- 20 GW of wind In 2008, 29 GW(e) of (non-hydro) renewables+77GW

hydro- ~10% of total US energy generation capacity.

Target: 10% of electricity by 2010. 25% by 2025.

China- 7.7% of energy from renewables

in 2005. Targets: 10% by 2010, 15% by 2020 Wind target- 20GW by 2020, possibly more (100GW?)

EU Directive 2008: National targets for 2020- 20% EU energy target

Share of energy from renewables in final consumption

2005 2020

Austria 23.3% 34%

Belgium 2.2% 13%

Bulgaria 9.4% 16%

Cyprus 2.9% 13%

Czech Republic 6.1% 13%

Denmark 17.0% 30%

Estonia 18.0% 25%

Finland 28.5% 38%

France 10.3% 23%

Germany 5.8% 18%

Greece 6.9% 18%

Hungary 4.3% 13%

Ireland 3.1% 16%

Italy 5.2% 17%

Latvia 34.9% 42%

Lithuania 15.0% 23%

Luxembourg 0.9% 11%

Malta 0.0% 10%

Netherlands 2.4% 14%

Poland 7.2% 15%

Portugal 20.5% 31%

Romania 17.8% 24%

Slovenia 16.0% 25%

Slovak Republic 6.7% 14%

Spain 8.7% 20%

Sweden 39.8% 49%

United Kingdom 1.3% 15%

International Sustainable Energy Organisation (ISE�O)

Economics

Comparative generating cost in EU - 10% discount rate (EUR)

2005 Projected 2030with EUR 20-30/t CO2 costGas CCGT 3.4-4.5 4.0-5.5Coal - pulverised 3.0-4.0 4.5-6.0Coal - fluidised bed 3.5-4.5 5.0-6.5Coal IGCC 4.0-5.0 5.5-7.0Nuclear 4.0-5.5 4.0-5.5Wind onshore 3.5-11.0 2.8-8.0Wind offshore 6.0-15.0 4.0-12.0

Electricity cost (US cent/kWh)MIT 2003 France 2003 UK 2004 Chicago 2004 Canada 2004 EU

2007Nuclear 4.2 3.7 4.6 4.2 - 4.65.0 5.4 - 7.4Coal 4.2 5.2 3.5 - 4.1 4.5 4.7 - 6.1Gas 5.8 5.8,10.1 5.9, 9.8 5.5 - 7.07.2 4.6 - 6.1Wind onshore 7.44.7 - 14.8Wind offshore 11.08.2 - 20.2First 5 gas row figures corrected for Jan 2007 US gas prices of $6.5/GJ (second figure for France & UK is using EU

Australian Uranium Association

European Commission January 2007

Powering the Nation

PBpower 2006

£/MWh Frontier Economics 2008

Past and Expected reductions from 1980 prices

Source: ‘U.S. Program in Renewable Energy-Effectiveness andProgress’, Stanley R. Bull, NREL, paper to WREC X

1980 1985 1990 1995 2000 2005 2010 2015 2020 2025

100%

50%

Learning Curve Data for Selected Energy Technologies

Costs of electricity by 2020

pence/kWh

On Land wind 1.5 - 2.5

Offshore wind 2 - 3

Energy crops 2.5- 4

Wave and tidal power 3 - 6

PV Solar 10 - 16

Gas CCGT 2 - 2.3

Large CHP/cogeneration under 2p

Micro CHP 2.3 - 3.5

Coal (IGCC) 3 – 3.5

Nuclear 3 - 4

Source: PIU Energy Review

UK Cabinet Office PIU study 2003

Long term cost trends

Share of renewable energies in gross electrical consumption

in European Union countries in 2005- and 2010 targets

/

UK1.3%

Next : the new EU targets for 2020

Austria 34%

Denmark 30%

Finland 38%

Latvia 42%

Portugal 31%

Sweden 49%

UK 15%

.. still a way to go

40%

REFIT systems are used by most EU countries

REFIT in Germany -degression of prices for wind

The Renewables Obligation

versus Feed In Tariffs

In 2005/6 the RO cost consumers

3.2/p/kWh, whereas in 2006 the

German Feed In Tariff only cost

consumers 2.6/p/kWh(Ernst and Young 2008)

0

10

20

30

40

50

60

70

2000-01 2001-02 2002-03 2003-04

Nuclear

Capital

Gants f or

Renewables

Renewables

R&D

DTI Funding for Energy £ million

Source: http://www.dti.gov.uk/expenditureplan/report2004/

Renewables UK

Govt. R&D

funding 2007-8

~ £28m

UK Energy Mix

Marsh/FES, 2005

UK Energy Mix

Marsh/FES,2005

Conclusions

UK Energy Research Centre- MARKAL UK electricity scenarios for 2050

Comparison of Nuclear and Renewables

Nuclear Renewables

Resource lifetime Uranium reserves ~100 years at current use

rates ~1000 years with FBR

Effectively infinite resource

lifetime

Resource scale Currently ~6% of world energy, ~17% of

electricity

Could perhaps be doubled? Or trebled? i,e.

to 50% of world electricity. But lifetime of

the resource would then be limited

Currently ~ 6% (with hydro)

~17% of electricity

Projection: 50% of world energy

by 2050 (RE2004/Bonn

Conference)

Eco impacts Infrastructure impacts, cooling water

impacts, risks from very long term wastes

~10,000 years

Local visual intrusion and land

use conflicts, some local eco-

impacts (especially with biomass

and large hydro)

Safety Major accidents ~10,000 deaths,

occasional/routine emissions ~100’s of

deaths

Generally low risk, except large

hydro ~10,000 deaths

Costs High and could rise as uranium resource

dwindles, but new technology could emerge

Some high but most are

moderate, and all are falling as

technology develops

Output Electricity only but could be used for heat or

hydrogen

Diverse sources: electricity,

heat, fuels

Reliability Occasional shut downs Some rely on variable sources,

so need grid integration to

balance outputs

Security Significant terrorist targets, plutonium

proliferation threa

No significant problems except

with large hydro

Expand Nuclear Power?* Can’t contribute short term: ~10 years to plan/build

* or long term: reserves of high grade uranium limited

In the meantime, creates further problems with:

* Accidental leaks and emissions

* Long term disposal of active wastes

* Proliferation of bomb making capacity and materials

* Potential Terrorist attacks

Renewables - mostly faster, cleaner, safer, cheaper,

with no emissions or wastes, no proliferation or terrorist threats,

and no fuel resource depletion worries

Nuclear FusionPlasma at 200

million degrees

JET at Culham

No wastes?Intense

radiation means that components become radioactive- and have to be striped out and stored

No fuel limitations?Reserves of lithium (for making tritium) are limited

No major or quick solution? The UK Atomic Energy Authority booklet ‘Fusion- a clean future’ says fusion ‘has the potential to supply 20% of the world’s electricity by the year 2100.’

Cost: So far

$20Bn, now

another

$20Bn in

ITER

So-why renewable energy?

• Fossil fuels will not last for ever-we face peaks in oil production and also for gas

• We can’t use all the fossil reserves we have without seriously disrupting the climate system

• Nuclear fission has many problems- e.g safety, security, long term uranium availability

• Nuclear fusion is a long shot, with similar problems

• Renewable energy sources have fewer problems-they seem like the only major long term solution

PV Solar is one of the big hopes for the future

New idea are emerging-10 Megawatt floating wind turbine

system

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

..some of them fanciful!

Giant 2000 ft high Selsam

‘Super turbine’

Half mile high concept

Some of them maybe more sensible

And finally..

Intermittency

Wind power variations

Demand Variations

Balancing variable renewables

At present, some gas plants are used the balance the variation in availability of conventional output and the daily cycles in demand. So they run up and down to full power regularly- perhaps twice daily.

With more variable renewables on the grid, they will have to do this bit more often.

It’s small operational issue, adding slightly to the system cost- in effect reducing the large cost and carbon

emissions savings enjoyed by not having to buy and use fuel by a few percent

0

1

2

3

4

5

6

0 10 20 30

Wind Capacity Installed GW

Cap

acit

y C

red

it

GW

Grubb

NGC

ILEX

Capacity credit for wind

How much conventional capacity can be replaced.

Rule of thumb: square root of wind capacity

Forecasting wind

When the percentage of wind power used rises beyond around 20%, then extra stand-by capacity may be needed- or other ways to balance the grid.

Denmark does this by importing hydro-electricity from Norway/Sweden when the wind in put is low.

Other non variable renewables might also be used for this balancing -e.g biomass fired plants, geothermal plants.

A study by the University of Kassel in Germany has found that it is possible to balance variable wind and PV solar with biomass wood chip combustion 100% over a full range of weather and demand cycles

www.unendlich-viel-energie.de/

de/strom/detailansicht/article/165/

the-combined-power-plant.html

The real issue is what to do with the excess electricity, when it’s windy and we don’t need it: we might use it in pumped storage plants, or convert it to hydrogen, to provide power when the wind input is low. Or export it.

That’s where the supergrid system comes into play-it would enable the variations in wind, and other renewables, to be balanced across a whole continent.

The big problem for the future is what to do with the excess power renewables might generate at periods of low demand, if we

have a large renewables capacity and also a large amount of nuclear on the grid.

Nuclear plants can’t easily load follow-and they are usually run 24/7 to recoup

their costs.

‘Baseload’ in the UK is about 20GW - e.g at night in summer.

We might soon have 20GW or more of renewables.

If we also had 20 GW of nuclear, as some would like to see, then any input from wind,

wave, tidal etc would have to be dumped

Curtailment

A way out? The new EPR can ‘load follow’ to some extent, and some existing French PWRs already do, but there are cost and operational and safety penalties.

Is this what we want? The question is- which output should we curtail at low demand times- wind or nuclear?

Basically large contributions from variable renewables like wind and from essentially inflexible nuclear plants don’t integrate well together….

Demand and Nuclear Output

( 20/01/08)

40

45

50

55

60

65

0 3 6 9 12 15 18 21 24

Hours

GW Demand

Nuc lear

'EPR nuclear plant design can provide levels of flexibility

that are comparable to other large thermal plant.

However, there are constraints on this flexibility (as

there are for other thermal plant). For example, the EPR

can ramp up at 5% of its maximum output per minute,

but this is from 25% to 100% capacity and is limited to a

maximum of 2 cycles per day and 100 cycles a year.

Higher levels of cycling are possible but this is limited to

60% to 100% of capacity’.

EDF

‘As the intermittent renewable capacity approaches the

Government’s 32% proposed target, if wind is not to be

constrained (in order to meet the renewable target), it

would be necessary to attempt to constrain nuclear

more than is practicable’.

EDF's submission to the UK governments renewable energy

strategy consultation: ‘UK Renewable Energy Strategy:

Analysis of Consultation Responses’ Prepared for: Dept of

Energy and Climate Change

www.berr.gov.uk/files/file50119.pdf

BERR’s visionof a possible 2020generation capacity mix

US generating costs in May 2008.

Source: California Energy Commission

0 5 10 15 20

Gas

Coal

Clean coal

Nuclear

Wind

Hydro

Geothermal

Biomass

GENERATING COSTS - ¢/kWh

Appendix

Costs of Renewables 2020 data

Technology Installed costs Load factor Generation cost €/kW %

€/MWh 5% tdr

8% tdr Onshore wind 760-900 16-25 35-55 43-67 Offshore wind 1200 33-40 35-42 42-51 Solar PV 1400-3100 8-16 316-697 393-865 Solar thermal electric 1000-2000 21-30 35-54 58-68 Biomass gasification 2250 97 36 43

Costs for nuclear and gas (£ per MWh/Euro per MWh)

Low Medium High Nuclear 30/45 37.5/56 43.7/65.5 Gas 24.5/37 34.6/52 4 5.2/68

Source: Department of Trade and Industry, ‘Nuclear power generation cost benefit analysis’ July 2006 http://www.dti.gov.uk/files/file31938.pdf

New Nuclear generation costs: 67-79 €/MWh, depending on

load factor and plant lifetime. ‘The future of nuclear power’

Massachusetts Institute of Technology, 2003.

UK RO: Renewables Obligation- a quota/ trading system

Overall renewable target increased in stages- 10% by 2010, 15% by 2015, 20% by 2020

Renewable Obligation Certificates (‘ROCs’) given for each eligible MWh

Suppliers pay ~ 3p/KWh ‘buy out’ fine if they don’t meet their RO target -that sets the prices ceiling for projects

Or they can buy ROCs from those who have more than they need- so ROCS are valuable and traded.

Prices variable- depend on the market for electricity and for ROC’s.

This uncertainty makes it hard to get investment capital for new projects- so suppliers have to

UK Renewables ObligationResults:

Relatively high prices and not much capacity e.g 3GW of wind

Some mature wind projects on good sites may get more subsidy than they need.

Cost to the consumer- 5-6% extra on bills by 2010

Less developed renewables can’t get started.

UK unlikely to meet its quite low targets, despite proposed modifications to RO-‘technology bands’ with different ROC allocations.

Capital grants have had to be provided to try to get new renewables going - £500m so far

German REFIT: Renewables Feed-In Tariff (EEG)

Suppliers have to pay fixed prices for renewablesPrices are set at different levels for each technology Prices are reduced in stages (‘degressed’) over time reflecting their expected development.

Results:

Massive expansion of wind (20 GW).

Also PV solar (~2GW)

Lower prices per kW and per kWh than Renewables Obligation

Cost to consumer ~3% extras on bills so far.

214,000 jobs created

Renewables Obligation pays out more than some mature projects now need

Renewables Obligation may pay out more than is need to some mature projects -including possibly on land wind projects on good sites

OFGEM estimates

in 2005

European Commission Support of Electricity from renewable energy sources 2005

Extra backup needed for 20% wind

Dale Fells Sinden

Comparison of backup scenarios for 20% wind powerAdvocates of different backup perspectives shown above relevant scenaio

50

60

70

80

90

100

110

120

130

140

No wind 20% wind,

65% additional backup

20% wind,

100% additional backup

20% wind,

22% additional backup

Scenario

Insta

lled

cap

ac

ity -

GW

Wind capacity

Additional backup

Conventional capacity

Maximum

conventional

capacity required

to meet demand

•Scenario 1: 26 GW (20% UK electricity) from wind needs c.5.7GW (22%) backup (Dale et al, 2004)

•Scenario 2: 26 GW (20%) wind needs 16.9GW (65%) backup (PB Power & RAE, 2003)

•Scenario 3: 26 GW (20%) wind needs 26 GW (100%) backup (Laughton, 2002, Fells, 2004)

•Figure: Sinden, 2007

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