Water-Energy Nexus: Can Nanotechnology Provide Solutions?

Shaurya PrakashDepartment of Mechanical & Aerospace Engineering

The Ohio State University

Water for the Americas

February 11, 2014

Water

Materials Food, agriculture

Energy

Societal Operations

Functional modern society

Economic development

Environment sustainability

Health and Wellness

Security

Water and Energy are Interdependent

• Thermoelectric cooling

• Hydropower

• Energy minerals extraction/ mining

• Fuel Production (fossil fuels, H2, biofuels, shale)

• Emission control

• Pumping

• Conveyance and Transport

• Treatment

• Use conditioning

• Surface and Ground water

Information Courtesy: Michael Hightower, Sandia National Labs, 2010

Energy and power production require water

Water production, processing, distribution, &

end-use require energy

United States Water Usage

Public and Self-supplied Potable Water

40,738.5(12%)

Industrial-Mining27,159.0-

(8%)

Irrigation-Livestock139,189.7 MGD

(41%)

• Total water withdrawn per year 123.9 trillion gallons, which is ~ yearly outflow of Mississippi river

• Direct energy demands (TE power generation) currently accounts for ~ 39% of all water withdrawal

Water Withdrawn in the US for All Uses

Thermoelectric Power

132,400.0(39%)

Costs directly

related to withdrawals:

Source matters

“Consumptive Water Use for U.S. Power Production,P. Torcellini, et.al., National Renewable Energy Laboratory, 2003.

Water and Energy: Two Sides, One Coin

• As just discussed, energy accounts for the largest water withdrawal including mining, refining, and generation

• Coal use for generation increases water loss by 33% over natural gas and nuclear. Coal to H2 doubles loss rate consumptive use!

• New sources of energy (biomass, syngas, hydrogen) will more than double current use per gallon or kWhr (4-6 gal. H2O/gal ethanol)

• Water withdrawals expected to be TWO orders magnitude larger with increased ‘new’ energy

Information Courtesy: Mark Shannon, U. Illinois

Impact on Energy

Without sufficient water: Challenging to increase energy use to meet the

needs of a growing population Difficult to transition to a hydrogen economy Our ability to use biomass and clean coal derived

fuels will be impacted We’re the Saudi Arabia of Shale Oil and Gas, but we

can’t utilize it without proper water use and disposal Increased demands for electricity for using plug-in

hybrid vehicles will be impacted as electric power generation is limited by water use

Can it be Worse? Population Growth (>1% per year ) and Population Shifts to Urban

Areas: Changes and increases demand in water, food, and energy• Local problems growing

• Logistics for distribution, management, maintenance will only get harder

Over-pumping of Ground Water Aquifers: Unsustainable Water, Energy, and Food: The complete nexus Contamination of Source Waters: Cross-contamination of surface

and aquifers is growing, reducing dilution solutions – more treatment is needed new technology is imperative• Finite (and increasing) energy costs

Current centralized water systems are capital, energy, and chemically intensive, and new systems are neither sustainable or affordable for growing populations

Snowpack Storage and Glacial Melting: Major river systems with shortages during dry months (Brahmaputra, Ganges, Yellow, Mekong Rivers, Blue Nile, Mt. Kilimanjaro, Andes, Rio Grande, Lake Mead, etc.)

Can Nanotechnology Help?

Nanotechnology provides unique opportunities• Provides physical basis for evaluating fundamentals

of how molecules interact

• Can build transformative advances by harnessing the ability to manipulate the basic building blocks of materials and systems

• System components and functional units will be at same length scales as physical phenomena that govern water processes

Basis for new technology solutions

Nanotechnology Can Help With…

Use chemicals only as needed: No more homogeneous chemical mixer systems to heterogeneous chemistry systems: catalysts, separators, absorbers, membranes (passive and active), biochemical, nanotechnology,…

Wastewater is Resource-water: Recovery of chemicals from wastewater – nutrients, ammonia, methane,…

Less exogenous energy: Increased renewables solar, wind, energy from waste (including wastewater),…

Sustainability from nature: Bio-inspired processes for contaminant detection, separation of contaminants and salts, bio-remediation of solids in wastewater, …

Desalination Example – Opportunity for Innovation

Current water desalination methods can be energy intensive

Process MSF MED/TVC RO ED*

Heat Consumption (kJ/l) 290 145-390 -- --Electricity Consumption (kJ/l) 10.8-18 5.4-9 9-25.2 4.32-9

Total Energy Consumption (kJ/l) 300.8-308.8 150.9-399 9-25.2 4.32-9

Typical Production Capacity (m3/day) ~ 76,000 ~ 36,000 ~ 20,000 ~ 19,000

Conversion to Freshwater 10-25% 23-33% 20-50% 80-90%Pretreatment required little little demanding moderate

* For brackish water

We are far from the natural law limits for separating contaminants from water: Currently at 4-100X times higher for nearly all

methods Lots of room to improve!

Nanotechnology Solutions for New Desalination Systems

Biological systems are close to thethese limits, and operate at the nanoscale

New water purification technologies using point-of-source supply, point-of-discharge, and point-of-use systems: The new (oldest) paradigm in infrastructure

New technologies can greatly improve how clean water is supplied and sanitation discharged – Can change everything!

Kim, S. J. et al. Nature Nanotechnology 2010

Chip-scale system at MIT to deliver de-salted water from seawater at a fraction of the energy cost

First generation lab device at OSU inspired by biology for desalination at thermodynamic limits

Prakash, S. et al., in Bionanotechnology II, CRC Press, 2011, Reisner, D. (Ed.)Prakash et al., Patent Pending (2013)

Paradigm Shift: Wastewater is Resource-Water – Extract Energy

U.S. municipal wastewater contains 7.2x109 kg of “dry solids” annually

• ~ 25 MJ/kg (7 kW.hr/kg) of energy content

• Total energy available ~2x1017 J (51 billion kW.hr).

Currently, most municipalities do not generate energy from bio-solids:

• 49% treated & applied to land, 45% incinerated or landfilled, 6% to other

U.S. 2008/2009 electrically generated: 14x1018 J

Energy content in wastewater is ~ 2% of US electrical demand(Nearly equivalent to energy from major renewables combined,

solar, wind, etc.)

Integrated Anaerobic Digester for Bio-Ammonia Harvesting

Harvest bio-gas (methane) and ammonia

Integrate with anaerobic digester with novel thermophilic microbes resistant to high ammonia concentration

Integrate with fuel harvesters

> 20% total enhancement in energy with hydrogen from ammonia in addition to methane possible!

Babson, Prakash et al. Biomass & Bioenergy (2013)

High Efficiency Microbial Fuel Cells

Energy extraction from waste (and wastewater)

Current technology limited by poor system efficiency

Bio-inspired structural designs to exploit fundamental features

• Sea-corals• Cow rumen

New materials for high efficiency operation

Gerber, Prakash et al. (2014)

Summary and Conclusions

Basic science

Conservation

Public-private partnerships

Economic opportunities in emerging markets

Technology innovation

Systems development

Implementation to central infrastructure

Creation/implementation to point-of-use infrastructure

Water-energy sustainability

Water and Energy is a coupled problem and must be addressed by bringing in ‘stakeholders’ at all levels (local to federal government, private enterprises, utilities, consumers, technology development, and market transition).

Acknowledgements

Prof. Mark Shannon (U. Illinois) Prof. A.T. Conlisk (Ohio State) Prof. D.E. Fennell (Rutgers) Matt Gerber, Marie Pinti, Clare Cui, David Babson Financial support: NSF, DARPA, NJWRRI

Thank you!

Questions?