The Water-Energy Nexus: Trading One Problem for Another?

Thanks for gathering that well-informed panel and for adding several dimensions to the water-energy discussion that had not been widely reported. The quantities of rainwater that can be harvested are impressive (600 gallons per 1,000 square feet of roof per inch of rain -- or for a 10,000 square foot commercial roof in an area with 25 inches of rain a year - 150,000 gallons per year). Compared to the inefficiencies and leakage involved with treating and pumping potable water great distances, distributed water collection (gathered where it will be used - just like distributed energy production) is an under-utilized resource that can help solve shortages of both fresh water and energy.
In addition, because water is the universal solvent, surface and ground water sources that have come in contact with industrial, agricultural and pharmaceutical pollutants (many of which are not required to be measured to meet the EPA standards for drinking water) are inferior to rainwater that has been properly harvested. Rainwater that has been captured before it hits the ground has simply been exposed to fewer pollutants compared to rain that was allowed to fall on the ground for later harvesting by water utilities. The mission of the 501(c)3 American Rainwater Catchment Systems Association (www.arcsa.org) is to promote sustainable rainwater harvesting practices to help solve potable, non-potable, stormwater and energy challenges throughout the world.

Is energy production really a cause of the water crisis or not? Irrigation of ethanol crops grown in dry areas could be a problem, but that is a small percentage in the US. The podcast says the huge electricity industry, with massive nuclear and coal power plants, consumes only about 3-4% of total water consumed. Moreover, that could be greatly reduced with dry cooling systems and water catchments. Both are not expensive, with dry cooling adding only 5-8% to costs. I don't trust Tom Rooney of SPG Solar since he seemed to be promoting solar and tried to claim there was still some evaporation with dry cooling, without explaining how much. I think small.

Such an interesting topic. I didn't know PV were a part of the water-energy nexus. It takes a full-time crew to keep everything clean...

pv and wind are the only renewables NOT part of the nexus, i.e. they don't use water to create energy.

great forum. great guests.

robertjohnson should listen to the podcast and read the other posts. pv and wind ARE part of the nexus because they use water in other operations besides creating energy. Both pv and wind use water in mftg. In addition, solar requires massive amounts for cleaning, as gdescobar mentions above.

Thank you for a seriously informative and compelling dialog on what will ultimately become a more broadly discussed situation in mainstream media. having lived in Southern California and Northern Arizona, water use and rights are highly contested. thanks to REW for this presentation. my education on the relevant issues is greatly enhanced here.

Wouldn't it be an achievement to drastically reduce water consumption involving toilets...i.e. composting solutions? The Humanure Handbook by Joseph Jenkins is a great resource on this topic and shows how removing human waste from drinking water sources greatly reduces the energy (equipment, chemicals, infrastructure) required to treat it.

I bet it will end up costing much less to solve the water problems created by generation technologies that produce heat (to run an electric turbine), than the storage problems created by the electricity generated by intermittent sources, like pv and wind.

In Portland, owners of installed solar panels say that cleaning needs are minimal. One fellow watches his output religiously and says he has cleaned maybe once per year.

Tom Rooney appealed to our best judgment when he asked that local conditions be considered when water/energy issues are negotiated.

As an example, burying water makes sense in a desert where evaporation is a big factor.

Floating generation makes sense even in a place where full-spectrum sunlight assists disinfection. Adding ph and other detectors also makes sense.

Generating power from solar is better than using fossils for pumps because pump failure is a risk both for interruption of delivery and for pollution.

Burying water is not sensible where radon is endemic or where nitrogenous compounds can be trapped or where determined life forms get into underground storage.

The expenditure of money and concrete is now demanded by an archaic EPA rule. The rule mandates logging, digging, and covering reservoirs, with fear-mongering about terrorists from afar.

Terrifying rules from D.C. are a bigger risk to Oregonians. If anyone offshore knew where Portland is, they would surely find us too weird to bother with, given our usual PR in the NYT and such.

The effect of this EPA rule will be to degrade water and simultaneously impoverish the already unadvantaged. Rents, fees, and interest income will flow to advantaged people to place egregiously energy-irresponsible concrete.

It is the IMF/World Bank way to indebt persons on-shore. Manipulators have perfected this pattern with offshore pilot practices and debt derivatives (Greece, e.g.).

Specific persons are arranging this damage, but these rackets cannot remain hidden.

The feds will, as usual, excuse themselves of responsibility.

Local persons and business entities will suffer consequences unless they move to Dubai in time to evade them.

The main problem we have with new renewable energy and water saving systems is that the innovators cannot get access to needed capital/loans to get from the lab stage to the proven prototype stage. The capital system demands low risk, high returns and proof of the same. VC's require a five times return in three to five years. That makes the cost of capital 300 to 500 percent per year. Most inventions are too modest to produce such. Here's the solution: Locally generated and locally used heating, cooling, electricity and storage. See: http://solarfurnacechp.wetpaint.com/page/SOLAR+FURNACE+SUMMARY
Jim Miller

Rainwater collection will impact river flows and groundwater recharge. It's not just an irrigator who might get shortchanged, how about an instream flow for fish overwintering, how about a wetland, how about drinking water?

Many other unintended consequences were addressed in the program, and I would like expert thoughts on this consequence of rainwater collection.

I design micro hydro systems that cleanse the water along with generating power and providing fish migration pathways.....Today, Maine's lakes, streams and basements are overflowing; so there is a distribution problem..nicely filled by Poland Spring and other distributors of our most excellent waters.

One thing we don't have a shortage of is gravity, when combined with falling water we can make electricity!

Rainwater collection, storage and sanitizing systems are far superior to the usually 'hard', sulphide laden water drawn from Island and coastal wells. Yet, this is not promoted by government; but actually discouraged. Any good answers?

Tom Rooney of SPG Solar was incorrect in his explanation of Dry Coolers. Dry Coolers are just that, dry. Perhaps he was thinking of hybrid coolers, which do consume water.

Dry coolers involve the use of a closed system with water run through a coil with a fan blowing air over that coil. No water is evaporated in the process. Water could be sprayed over the dry coils to increase the rate of heat rejection and evaporate water, but this type of cooler is no longer a "Dry Cooler".

It is possible to generate power with a thermal electirc plant using no evaporation of water for the thermodynamic cycle, at a penalty to the efficiency of the cycle.

You missed the most important point. All that cooling water used in power generation is to get rid of WASTE HEAT! Why not stop wasting 2/3rds of our energy by doing cogeneration?
The problem is with our mega-scale power plants. Power generation should be located where heat is needed for other applications. If the plant is sized to the need for heat, there need be no waste. We would use half as much fuel and very little water. Here is an article:
http://www.renewableenergyworld.com/rea/news/article/2008/07/heat-is-power-lets-stop-throwing-it-away-53123