Conservation Archives - Artemis Water Strategy

We don’t hear much about the benefits of solar power as a water saver, but solar and other renewables will be critical in providing a steady flow of energy as major droughts become common.

Cooling towers at the Ratcliffe-on-Soar Power Station, United Kingdom. — Ratcliffe-on-Soar Power Station, United Kingdom

“The future of energy production in the US for the next decades is being decided today,” notes Jigar Shah, founder and former CEO of Sun Edison and a partner at investment fund Inerjys. “Over 70,000 MWs of coal being retired by 2020, and it will be replaced by natural gas, renewables and energy efficiency. Climate change and droughts are forcing public service commissions to take water use into account when planning that future. Given the water scarcity we will be facing, renewables and energy efficiency are leading the way.”

While power plants consume only 4% of our freshwater supplies, they use more than 40% of US freshwater resources for cooling and send it back into lakes and rivers . Each day, big centralized coal-fired, natural gas and nuclear plants use more than 60 billion to 170 billion gallons of freshwater from lakes, rivers and aquifers for cooling. Coal-fired energy plants are responsible for 67 percent of those withdrawals. It requires more water, on average, to generate the electricity that lights our rooms, powers our computers and TVs, and runs our household appliances, than the total amount of water we use insides our homes everyday.

These “water hogs” power plants have not been built to adapt to water scarcity. The heat waves and drought that hit the US in 2011 and 2012 shined a harsh light on the vulnerability of its fossil fuel-powered electricity infrastructure. In 2011, Texas power plant operators trucked in water from remote sites to keep their plants running.

During the summer of 2012, power plants through the US, including the Midwest and Northeast, were forced to reduce operations or shut down. Seven Midwest nuclear and coal plants received permission to put aside environmental regulations and discharge warmer cooling waters that damage water ecosystems.

The US Energy Information Administration (EIA) projects that the US will continue to rely on massive supplies of freshwater for energy as natural gas replace coal-fired energy plants. EIA projections chart limited growth in renewable energy and marginal energy efficiency (see the chart below). However, the National Renewable Energy Laboratory’s Regional Energy Deployment System (ReEDS) has developed a model that considers a bigger role for low-carbon electricity sources and charts their impact for freshwater requirements through 2050. The 2012 report, “The Water Implications of Generating Electricity,” evaluates different water sources and the water requirements of current portfolio of electricity generating plants technologies in the US. The report contrasts the EIA scenario with others, including one scenario (below), the report assumes aggressive deployment of energy efficient technologies and buildings. In that scenario, US electricity demand would drop 20% by 2035 and 35% by 2050 versus the reference case, while generation from renewable energy technologies (wind, solar, geothermal, biomass and hydropower) would increase from 10% in 2010 to 50% in 2035 and 80% by 2050.

The report estimates that aggressive implementation of renewable energy and energy efficiency would save 1.1 trillion gallons of water per year. More importantly, however, this wide base of decentralized energy that would be independent of water supply would ensure energy resilience during the droughts and water scarcity shocks that we expect in the future.

The short-term future of water will include scarcity shocks. We don’t know where they will hit, but it only takes another dry summer to bring on a more brutal season of plant shut downs and energy brown outs. In the aftermath, the cost of water-intensive fossil fuel energy will be much clearer.

Middelgrunden Windmills Outside Copenhagen — Efficient desalination can utilize alternative energy, like these Danish windmills, thus relying on the ocean twice. / Photo: andjohan on Flickr

The most common question I field when I mention desalination is, “Doesn’t that take a lot of energy?”

The truth is, yes, it does. That’s why you’ll not hear me advocate for desalination without strongly insisting on complementary conservation.

We must redouble our conservation efforts by upgrading infrastructure intelligently and in no way excuse wasteful water practices by pointing to the plentiful, historical ingredients of desalination: oceans of water and oceans of coal.

Each barrel of freshwater extracted from the ocean has costs, so we should use the water as efficiently as possible, recycling it and then remediating it into the water cycle.

Yet, conservation alone isn’t going to meet our water needs. The world’s population is expected to increase by 2.5 billion over the next 30 – 40 years, while the current, natural water cycle is not expected to increase its output.

Just as we must increase conservation, we must prepare for the impending water plateau by increasing our capacity to produce fresh water.

Hence my excitement in June when I heard about Desalitech’s successful pilot.The test purified Mediterranean saltwater, using Desalitech’s proprietary Closed-Circuit Desalination saltwater reverse osmosis method (SWRO-CCD).

Using common components, without energy recovery, running a high-pressure pump at 81% mean efficiency and circulation pump at 37.5% mean efficiency, the pilot achieved 48% recovery at 2.05 – 2.40 kWh per cubic meter of fresh water. For comparison, Perth’s desalination plant using Energy Recovery from ERI achieves 43% recovery at 2.32 kWh/m3.

Desalitech aims to increase the mean efficiency of the off-the-shelf, high-pressure pump to 88%, to provide recovery at 1.75 – 1.95 kWh/m3 on Mediterranean saltwater. The same pumps used on ocean water could produce equal recovery at 1.5 – 1.7 kWh/m3.

Desalitech’s implementation reduces the cost of powering desalination processes. It also decreases capital expenditures. Nadav Efraty, CEO of Desalitech, told me, “This technology is reducing energy consumption by up to 50% when we utilize about twice the membranes, reduces energy by about 10-15% when we use only 40% of the membranes compared to a conventional plant, or reduces energy about 30% when we utilizes the same amount of membranes, but in this mode, since we don’t utilize any form of energy recovery, we still see a reduction in capital expenditures.”

Even with less than half the membranes, the technology still sees 10-15% energy reduction. That’s a 60% savings on capital expenditures for membranes.

As an added element of efficiency, plants utilizing Desalitech’s technology can turn plants up and down depending on demand: Nadav explained, “The very same unit can operate at very high production rates part of the day (when power rates are low for example) and in extremely low energy consumption the rest of the day.”

Desalitech does this by independently controlling component flow rates, recovery, pressures and cross flow irrespective of the other variables.

Following their successful pilot, Desalitech is addressing brackish water. Desalitech’s three BWRO installations are fully operational facilities, capable of producing 10,000 m3 fresh water per day.

Solar’s role in a thirsty future

Desalitech Reduces Costs of Desalination

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