Artemis Water Strategy

Water resilience for a thirsty future

Jun 27 2016

Hawaii’s sweltering heat emerges as a new challenge to schools

As Hawaii’s cooling tradewinds have faltered and ocean temperatures rise, Hawaii’s leadership moved earlier this year to invest a significant chunk of its resources, more than $100M, to cooling its schools. Last year, temperatures sweltered above 100 degrees, and health concerns forced the Hawaii Department of Education (HIDOE) to consider suspending school for “heat days.”  In Hawaii, the heat crisis in schools is shining a stark light on in-building heat as an obstacle to the State’s prosperity and economic survival. Only 6% of the state’s classrooms have air-conditioning, and Hawaii’s Department of Education (HIDOE) estimates that installing air conditioning in all classrooms would cost $1.7B and saddle schools with an even heavier burden of maintenance expenses.

Air conditioning:  Antidote to the “Curse of the Tropics”

Thermal image taken in classroom at Ilima Intermedate in Ewa Beach on September 12, 2014. The Celsius temperature reading of 35.0 in the upper left corner is equal to 95 degrees Fahrenheit.
Image: PF Bentley/Civil Beat: Thermal image taken in a classroom at Hawaii’s Ilima Intermediate middle school, where midday temperatures measured 35.0 C or 95 Fahrenheit.

Air conditioning has been one of the unheralded tools behind the success of other tropical economies, such as Singapore, and desert economies such as Israel, in the latter 20th Century.  Economist Jeffrey Sachs quantified the impact that air conditioning has had in tropical economies on productivity by simulating temperate environments that enabled northern countries in Europe and North America to attain leadership during the 19th and 20th centuries.

But as air conditioning helps Hawaii overcome one of the “curses of the tropics,” it carries a financial burden and makes their energy burden heavier.   An analysis of schools with campus-wide AC compared with schools of similar size and relative location that do not have campus-wide AC indicates that the cost of electricity may increase by more than 80% in an air conditioned school.  The HIDOE spends more than $62 million a year on electricity, gas, water, and sewage fees — a 50 percent increase over the past ten years. HIDOE estimates it will pay an electricity bill of $47.6 million this year.Worldwide power consumption for air conditioning alone is forecast to surge 33-fold by 2100 as developing world incomes rise and urbanization advances.

Ka Hei: Hawaii makes cooling part of the curriculum

With limited budgets, the state of Hawaii has designed a program that taps into community resources along with innovation and renewable energy sources. It’s ambitious Ka Hei program combines the facility upgrades for cooling with science and engineering education. The program is attempting design the heat abatement program to empower our students and teachers to adapt new ideas about sustainability for the benefit of our greater community.  In Hawaiin, Ka Hei is the snare made of ropes that the Hawaii god Maui used to capture the sun.  Ka Hei also means “to absorb as knowledge or skill.”http://www.hawaiipublicschools.org/ConnectWithUs/Organization/SchoolFacilities/Pages/Ka-Hei.aspx

Through a combination of energy efficiency measures, clean energy generation (including the HIDOE’s ongoing photovoltaic project, small-scale wind turbines, and other viable systems) and a comprehensive sustainability program, HIDOE is designing Ka Hei to improve the learning environment so students and teachers can perform at their best.  Current options include passive cooling, which prevents heat from entering a building, and night thermal flushing to get rid of stored heat in a classroom overnight. Even when supplemental mechanical cooling is necessary, these concepts make conventional air conditioning (AC) systems more efficient. HIDOE has also been piloting new technologies that could reduce cost and be more sustainable. One of the most promising is photovoltaic (PV) air conditioning. A portable classroom at Waianae High is into its second year of running a pilot system using three PV panels for each AC unit.

Futuristic design grows out of need for savings
The “energy positive” building sits on the campus of Ewa Elementary School. Image: Hawaii Department of Education

Written by Laura Shenkar · Categorized: Cooling, Policy · Tagged: cooling, Hawaii, sustainability

Jul 28 2010

Engineers Turn Water Contaminant into Fuel

 

Aerial Top Dusting Is a Leading Cause of Water Contamination from Nitrates
Aerial top-dusting is a leading cause of water contamination / Photo: tjmartins on flickr

Researchers in Delaware are worried by high levels of nitrates recently discovered in groundwater and drinking water. A recent study found 76% of domestic wells contained nitrates. 18% of the wells exceed federal standards for drinking water.

Even some deep wells are affected, leading Delaware’s Department of Natural Resources to conclude that surface contaminants are penetrating natural barriers, meaning “ground-water quality in a significant fraction of confined aquifer wells is susceptible to human activities.

“Nitrates reach surface waters and groundwaters via septic systems, stormwater runoff and fertilizers used at farms, homes and businesses including golf courses. Nitrates threaten pregnant mothers, children and, in sufficient concentrations, nitrogen-rich waters precipitate eutrophication, contributing to dead-zones like in the Gulf of Mexico.

Nitrates that don’t directly enter surface waters and groundwaters are typically removed from the wastestream at wastewater treatment plants, either via efficient processes like Ostara’s Nutrient Removal Technology (which removes nitrogen in the from of NH3, aka ammonia) or via energy intensive processes utilizing aerobic bacteria.

But now a couple of rocket scientists and a waste expert from Stanford have devised a way to safely and efficiently dispose of nitrates while powering wastewater treatment plants without an external energy source.

Greenhouse Gases as Resources

Rocket Engine via Stanford
Rocket Engines Burning Nitrous Oxide produce pure Nitrogen and Oxygen / Photo: Brian Cantwell at Stanford

As we’ve discussed previously, wastewater treatment processes utilizing aerobic bacteria require energy intensive aeration in order to operate (up to half of operating costs). Anaerobic bacteria require much less energy, but convert nitrates into nitrous oxide – a greenhouse gas 300 times more potent than C02 – and Natural Gas in the form of a methane biogas.

The scientists, Craig Criddle, Brian Cantwell, and Yaniv Scherson, have decided excess gases aren’t such a bad thing. In fact, they want to utilize produced Natural Gas to power wastewater treatment plants off-the-grid, enabling plants to be placed in areas without a reliable energy supply. The plants could recycle fresh water for water–stressed regions.

What happens to the nitrous oxide is equally remarkable.The nitrous oxide is burned off in a small rocket engine. Says Cantwell, “When it decomposes, nitrous oxide breaks down into pure nitrogen and oxygen gas. At the same time, it releases enough energy to heat an engine to almost 3,000 degrees Fahrenheit, making it red hot, and it shoots out of the engine at almost 5,000 feet per second, producing enough thrust to propel a rocket.”

To propel a rocket, or, put to better use, to generate electricity.The scientists’ plan harvests resources commonly occurring in wastewater. “For too long we’ve thought of treatment plants as places where we remove organic matter and waste nitrogen,” Criddle said. “We need to view these wastes as resources, not simply something to dispose of.”

Saving Money while Saving the World

In the developed world, the technology could produce wastewater treatment plants with low emissions (some natural gas will be emitted when combusted).

That’s important because wastewater treatment plants accounted for 4.9 TgCO2 equivalents of nitrous oxide in the US in 2008 (equivalent to 4.9 million metric tons of C02).

When you utilize instead of emitting the methane produced by wastewater treatment, which reached 24.3 TgCO2 in 2008, and eliminate expenditures and emissions from energy used to power aerators, you begin to see the scale of potential energy, emissions and cost savings.

It’s a remarkable advance: a self-sufficient, low-emission wastewater treatment plant that produces nitrate-free fresh water, thereby protecting water’s end-users: aquatic and human life.

Via PhysOrg / Stanford

 

Written by Laura Shenkar · Categorized: Resource Recovery, Waste-to-energy, Wastewater Treatment · Tagged: Delaware, fertilizer, groundwater, methane, nitrates, resource recovery, rocket fuel, rocket science, Stanford, stormwater, sustainability, wastewater, wastewater treatment

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