Understanding the water requirements of the power sector, by Anna Delgado from the World Bank

UNDERSTANDING THE WATER REQUIREMENTS OF THE POWER SECTOR

the complexities and challenges of determining water use by different power generation technologies

Anna Delgado Martin, Technical Specialist, the World Bankadelgado@worldbank.org

Huge ranges!WHY?

SOURCE: IEA WORLD ENERGY OUTLOOK 2012

Almost all forms of electricity generation require water

3

Only Wind and Solar PV have a negligible impact on water resources

HYDROPOWER

THERMAL POWER PLANTS

Thermal Power Plants account for about 80% of global electricity generation

SOURCE: IEA WORLD ENERGY OUTLOOK 2012

Thermal power plants

What drives water use in thermal power plants?

1. The type of cooling system used

2. The efficiency of the power plantand not that much the type of power plant

Other: climate conditions and other processes in the plant

The more efficient the less heat losses Less cooling needs

All the waste heat (“loss”) has to be rejected somehow to the environment. The vast majority of this heat is rejected to the environment through cooling systems.

Example of Efficiencies:

Natural Gas Combined Cycle: ~50% Super Critical Pulverized Coal: ~39% Subcritical Pulverized Coal: ~36% Nuclear: ~33% Solar Thermal (Rankine Cycle) : ~32% Old coal power plants: as low as 20%!

Electricity

Flue gas

Other

SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

Heat to be dissipated through cooling system

Example of heat balance of fossil fuel power plant

less cooling needs

more cooling needs

Thermal Power Plants

SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

Example of Pulverized Coal Power Plant

Efficiency: 36.8%

Example of Pulverized Coal Power Plant with Carbon Capture and Storage

Efficiency: 28.4%

Cooling TowersOnce-through cooling

Dry cooling

SOURCE: RUTBERG, 2012 AND DELGADO, 2012

Type of Cooling System

Withdrawal vs consumption

ConsumptionWithdrawal

Source: US freshwater withdrawals and consumption (USGS 2005 data)

US data does not include hydropower or nuclearIn the US there are still a lot of old plants and once through cooling systems

Impact of banning once through

Source: own estimations

Retirement of less efficient and older power plants Cost of electricity could increase water withdrawal/consumption totals would change

Impact of banning once through

Non-cooling process water usesFlue gas

desulfurizationBottom ash

handlingGasification /

Water Gas Shift

C + H2O CO + H2

CO + H2O CO2 + H2

Mirror surface washing

Boiler feedwater makeup

Coal Coal IGCC (Coal or biomass)

Solar All steam-cycle

~200 L/MWh(consumed)

~100 L/MWh(reusable)

~200 L/MWh(consumed)

~20 L/MWh(consumed)

~20 L/MWh(reusable)

Compare to ~2000 L/MWh consumed in typical cooling tower!

But even small water streams can incur large economic costs, e.g. Hg removal for discharge…

SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

Heat Rate vs. Water UseFor a given coolingsystem:

Heat Rateexplains most of thevariation betweenCases

Most of the water isused for coolingpurposes (85% to 95%)

SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

WATER WITHDRAWAL VS HEAT RATE FOR DIFFERENT POWER PLANTS WITH COOLING TOWERS

“Wet-cooled concentrated solar power plants use slightly more water than coal and natural gas; however, concentrated solar power plants can be designed to use dry-cooling, thereby reducing water demand by more than 90%. “

“Wind and solar energy consume little to no water and generate negligible carbon emissions”.

SOURCE: Forbes, 2013

“According to the DoE's National Renewable Energies Laboratory, whose figures are cited in the report, a typical hydroelectric power plant uses between 15,000 and 68,000 litres of water per megawatt hour generated, while a typical concentrating solar plant – which uses mirrors to focus sunlight onto a small area – uses about 3000 litres of water per megawatt hour of electricity generated.”

SOURCE: Stanford, 2013. water energy literature review

Misleading quotes from articles and reports

“Today’s generation of technology and cleaning frequency assumptions result in CSP consuming approximately five times more water than a gas-fired power plant, two times more than a coal-fired plant and 1.5 times more than a nuclear plant”

“concentrated solar power consumes large quantities of water”

“water intensive nuclear power stations should be replaced by renewables and natural gas, which consume less water”.

“The figures also show that a nuclear power plant uses 2650 litres per megawatt hour, whereas a typical coal fired power plant uses 1900 and a natural gas plant 750.”

Misleading quotes from articles and reports

Keymessages

Most of power in the world is generated by thermal power plants Water use in thermal power plants is dominated by cooling The amount of water required for cooling will depend on the cooling system used Given the same type of cooling system, the amount of cooling water consumed is mainly determined by the power plants’ thermal efficiency, irrespective of the type of fuel used Given the range of efficiencies within the same type of power plant (old vs new) it is almost impossible to give a single water factor for a a power plant technology Some low-carbon thermal generation technologies, which tend to be less efficient, may be at risk from a water availability standpoint or may have to use more expensive dry cooling systems The Water and Energy Nexus is a regional problem Need context specific solutions. One solution does not fit all

UNDERSTANDING THE WATER REQUIREMENTS OF THE POWER SECTOR

the complexities and challenges of determining water use by different power generation technologies

Anna Delgado Martin, Technical Specialist, the World Bankadelgado@worldbank.org

THANK YOU