1. Water-Energy Nexus: Can Nanotechnology Provide Solutions? Shaurya Prakash Department of Mechanical & Aerospace Engineering The Ohio State University Water for the Americas February 11, 2014

2. Water Materials Food, agriculture Energy Societal Operations Functional modern society Economic development Environment sustainability Health and Wellness Security

3. Water and Energy are Interdependent Thermoelectric cooling Hydropower Energy minerals extraction/ mining Fuel Production (fossil fuels, H 2, 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

4. United States Water Usage Public and Self- supplied Potable Water 40,738.5 (12%) Industrial-Mining 27,159.0- (8%) Irrigation-Livestock 139,189.7 MGD (41%) Total water withdrawn per year 123.9 trillion gallons, which is ~ yearly outflow of Mississippi river Direct energy demands (TE power generation) currently accounts for ~ 39% of all water withdrawal Water Withdrawn in the US for All Uses Thermoelectric Power 132,400.0 (39%) Costs directly related to withdrawals: Source matters Consumptive Water Use for U.S. Power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.

5. 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 H 2 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. H 2 O/gal ethanol) Water withdrawals expected to be TWO orders magnitude larger with increased new energy Information Courtesy: Mark Shannon, U. Illinois

6. 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 Were the Saudi Arabia of Shale Oil and Gas, but we cant 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

7. 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.)

8. 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

9. 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, …

10. Desalination Example – Opportunity for Innovation Current water desalination methods can be energy intensive * 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!

11. Nanotechnology Solutions for New Desalination Systems Biological systems are close to the these 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)

12. Paradigm Shift: Wastewater is Resource- Water – Extract Energy U.S. municipal wastewater contains 7.2x10 9 kg of dry solids annually ~ 25 MJ/kg (7 kW.hr/kg) of energy content Total energy available ~2x10 17 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: 14x10 18 J Energy content in wastewater is ~ 2% of US electrical demand (Nearly equivalent to energy from major renewables combined, solar, wind, etc.)

13. 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)

14. 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)

15. 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).

16. 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?