Water from Air Systems as a Supplement to Local Water Supplies for Coastal Areas
Coastal Cities Summit
S.R. Tatro, Ph.D.
Coastal regions are particularly vulnerable to natural disasters such as hurricanes, and ports such as Tampa are vulnerable to terrorism. After a disaster, surface water is likely to be polluted with oil, debris, perhaps toxic chemicals and sewage. Even when electricity is available to operate traditional water treatment systems, the available water may not be not suitable to be treated with existing purification systems. When supplies of surface and utility provided system water are unavailable, the condensation of water from humid air has the potential to provide point of use emergency personal potable water supply much more efficiently than delivery of bottled water supplies.
Distributed point of use water production can dramatically reduce the impact of natural and other large scale disasters. Immediate widespread emergency potable water supply can dramatically reduce humanitarian suffering and facilitate government responses by reducing critical demands, especially at the initiation of an emergency period before significant relief resources can be mobilized. Point of use water supplies will also dramatically reduce demands on the logistics chain.
In addition, most areas having humid air can benefit from water from atmospheric water harvesting systems year round to provide high quality drinking water with a low carbon footprint. The locations where atmospheric water harvesting (also known as water generation) can be carried out most effectively include most coastal regions of the world in tropical and temperate regions.
Water is the essential resource for life. The life expectancy of an individual with no access to water is dependent on many variables including initial hydration, overall health, temperature, and humidity. In hot weather, life expectancy can be as short as 2 days if no water is available.
Since 2001 there has been a heightened awareness in the United States of the need to be prepared for incidents that can knock out essential resources such as power and water. Threats include an ageing power and water infrastructure, terrorism threats and, in the Southeastern United States, hurricanes. The hurricane seasons of 2004/5 and the inadequate response from government were a reminder that it is each and every person’s responsibility to be prepared. The Federal government has now admitted that large-scale aid will not be available for major disasters for at least three days and possibly longer. This has lead to an increased awareness to individuals to provide personal backup power and water supplies.
Only a few examples highlight the need for local preparedness. Recent water outages in Fort Worth Texas on February 29th, 2008 highlight the vulnerability of municipal water systems to outages. The pumping stations rely on electricity, and are therefore threatened by electrical outages. In the case of the Fort Worth outage, a squirrel caused a loss of water to 30,000 residents and forced 380 businesses to close. Even though power was restored to the water pumping stations just hours later, it took at least 18 additional hours for the water system to be deemed safe for public consumption. Water outages were also caused by the Northeast blackout of 2003 in Michigan and Ohio. San Juan Puerto Rico was forced to shutdown water service to 1 million people for a whole weekend while they repaired a major pipeline.
Although the need for clean water is continuous, there is a conspicuous dearth of solutions to provide clean drinking water when the municipal water supply is disabled or unsafe apart from prepositioned storage, which has limited life. After a major water outage, such as after a hurricane, bottled water can be consumed quickly and local supplies can be exhausted. On a large scale this creates logistical issues for local authorities attempting to distribute adequate supplies of bottled or tankered water to the distressed population.
Power and water are two essential resources that are demanded by American citizens at all times, and their value increases sharply with scarcity. Standby and backup power generators are available in various sizes, and able to supply a whole house with power. No similar complementary products are generally available in the market to supply backup or personal water supply.
The standby power generator market has grown exponentially between 2000 and 2005, by 566%, according to research from Generac Power Systems, Inc., one of the two leading manufacturers of backup generators in the United States. A strong driver of this growth in generator sales is a desire for people to become more self-sufficient and prepared. A leading generator dealer in Boca Raton estimates that in the next 5 years more than 170,000 generators will be installed in Florida alone. The widespread use of power generators allows the use of water generators even when there is a power outage, and the combination of the two provides both water and power to keep a family comfortable until these resources have been restored.
For disaster preparedness, the Federal Emergency Management Agency (FEMA) recommends that each household store at least 1 gallon of drinking water per day per person to provide a minimum of 3 days’ supply. Using those recommendations, a family of 4 should store at least 12 gallons, and a family of 6 should store at least 18 gallons. This requires considerable storage space, especially when the stored water has a limited life of about six months as drinking water. This requires an intermittent restocking and dumping of old stored water. If the water outage or boil water notice lasts longer than the stored water supply, people must find some other source of water. This is usually provided by local or federal relief agencies. Additionally, bottled water should only be kept for six months.
In addition to disaster relief, other areas that would benefit from water generators include remote areas where water quality requires considerable or complex treatment or water supplies are generally unavailable. These areas include oceanic islands (Caribbean, South Pacific, small offshore islands), most of which are chronically short of water. This is especially true for low-lying islands that have little or no adiabatic rain. In addition, inland areas, including suburbs, which are commonly humid in the summer, including most of temperate eastern North America (Wisconsin, Georgia, Ohio, etc) commonly have persistent humid air masses. and are also incipient water generator localities. Prime geographic areas of the world include the Pacific Region, which has hundreds of oceanic islands, equatorial and coastal Africa, SW Asia, and most coastlines that commonly have onshore breezes, even where there may be deserts within tens of miles of the coastline. These commonly have persistent very humid, warm air masses, from which large amounts of water may be extracted.
Some areas have continual water stress and some have stress brought about by natural disasters. In the Southeast United States and Gulf Coast regions, hurricanes are a threat six months out of the year. Hurricane Katrina illustrated how devastating a hurricane could be to a community and demonstrated the substantial opportunity for improvement in providing fresh water to the victims. In Burma, after Cyclone Nargis hit in May 2008; there was substantial concern that the death toll would increase even after the storm due to the lack of accessible fresh water and water-borne illnesses.
Bottled Water Supplies
Currently, the accepted response after a natural disaster or other cause of water shortage is to deliver bottled water. Delivery is accomplished both by air and by ground. Given a county of 1 million people, if half of the population evacuated before the disaster and of those remaining, 75% had adequate personal water supplies, 125 thousand people would require water supplied through a disaster relief effort. Based on the the suggested amount of 1 gallon per person per day suggested by FEMA and the American Red Cross, 125 thousand gallons of water would be required per day. Applying a purchase prices of $0.80 gallon and a transportation cost estimate of $2.32 (ground) and $7.60 (air delivery estimate according to US Pentagon figures), the cost to supply water to the region would be in the range of $390,000 - $1,050,000 per day depending on what portion of the water had to be delivered by air to the region. These figures do not include the costs of prepositioning logistics for storage or pre-disaster distribution. This solution requires daily delivery and incurs a huge logistical cost.
In contrast, using an alternative method to provide for personal water supplies, such as Point of Use (POU) water generation, overall cost could be greatly reduced along with the strain on logistics. Continuous distribution from outside the relief area would be virtually eliminated, and the supply of water would be continuously regenerated within the area itself. For example, with the 20 gallon/day model of the AquaVentus water generator, an initial distribution of apparatus would be required, but then the water production would remain close to the point of use. The current projections for water production costs are in the range of $0.10 - $0.12 per gallon. To supply water to 125,000 people, the daily cost would be approximately $12,500 - $15,000 in energy costs. Once the initial units had been distributed, no further distribution would be necessary. The unit can be powered through personal and local power generation installations, which are quickly becoming commonplace, or through the power grid if available.
Water from the Air
The efficiency of removing water from air and the volume of water able to be removed are dependent on two basic parameters: temperature and humidity, as well as the POU water generating potential. At higher temperatures the air is capable of holding more water than at lower temperatures. Therefore there is more potential to remove water from air at higher temperatures. For example, if two air masses had 80% relative humidity it would be more advantageous to attempt to remove water from the air mass at 80 °F than air at 60 °F, because the air at 80% relative humidity and 80 °F would have more water than air at 80% relative humidity and 60 °F. These same air properties also dictate that the best and most efficient way to remove the water from the air in each of these cases is not the same.
AquaVentus is in the business of providing safe, secure interruptible water supplies to households and businesses using our water-from-air products.
AquaVentus has developed an innovative solution to standby POU water generation. A portable AquaVentus water generator will produce about 20 gallons of clean drinking water per day… from the air. This is enough water to keep a family of 4-6 comfortable during a water outage event, and is not dependant on a bottled water storage supply. The AquaVentus will continuously produce water in most climates (Fig. 1) and requires only a small source of electric power, either from the grid or from other sources such as a standby generator. It is an environmentally friendly system that produces water for much less than the cost of bottled water, without the waste associated with bottled water, and with a much smaller carbon footprint than bottled water. The AquaVentus water generator can be stored for long periods until required for use, and then will work out of the box with no need for trained operators.
The AquaVentus 20 gpd model (Table 1) is very simple to operate because it is completely automated. It has been successfully tested by the US Army. Simply press the ON button and the system will automatically produce water and adjust itself to the outside conditions. The proprietary control system that has been developed for this AquaVentus controls airflow to provide for the most efficient operation and water output at any given temperature and humidity condition. This makes the AquaVentus smart, and requires no input from the user.
AuqaVentus can be installed near a standby generator where water either can be plumbed into the house or collected outside. Larger units can produce up to 200-300 gpd.
The AquaVentus company has studied the water carrying capacity of the air over ranges of temperature and humidity and have developed extensive knowledge of the physical parameters that control the efficient extraction of water from the air. The process consists of two primary steps. First, removing moisture from the air to produce water using a highly efficient, state of the art, environmentally friendly refrigeration system. Second, treating the water using an on-board, state of the art water treatment techniques on demand to remove any potentially harmful organisms.
More than 2 years under development, AquaVentus has the most efficient water-from-air production available. The proprietary, patent pending design uses advanced airflow control and a passive heat recovery device that can be activated at lower humidity to increase efficiency and water output. The process and system design are scalable to allow development of smaller and larger capacity air to water systems.
A target market is disaster preparedness organizations including Federal, State and County agencies, as well as private organizations such as the Red Cross. All of these organizations stockpile a large amount of bottled water in the case of a disaster and would also benefit from alternative water supply options. Other target markets include companies and individuals, and local authorities not directly concerned with disaster relief and any locality with diminishing natural water resources.
AquaVentus can be be part of the disaster relief solution. Water supply is all around us right now as humidity in the air. This invisible ocean is available for tapping and use as both a primary source of personal water on a daily basis and for disaster relief. The U.S. population is increasingly interested in making sure their power supply is reliable, and AquaVentus will ensure their water supply is clean and reliable with less environmental impact.