Zero Height Roof

We have invented a new form of steel roofed building called the Zero Height Roof (ZHR).  It utilises conventional roofing products such as corrugated steel roof sheeting, and baton systems but combines them with a novel cable-like truss system.  Unlike desalination the ZHR produces water without consuming energy.  The undercarriage of the roof would have a service life exceeding 200 years, whilst the skin or roof surface, even with conventional roof sheeting, a minimum of 40.  With careful material selection a 100 year service life for the roof surface could be reasonably expected.  Given its low installation cost, its long service life, and its energy free operation it is able to deliver water to the regions straddling the Dividing Range at a discount to that required to fund and maintain desalination.  The truth is, many dream of a world where there is large scale collecting of rain water but none have devised a rational system for actually getting the job done.  The ZHR can do it with ease.  At first glance one might be tempted to conclude the correct path is the cover an area with plastic to produce a large scale artificial catchment.  But how would it breath?  How would it react after a day in the sun, would it bubble and balloon?  How might it be held down on a hot sunny day with a strong wind?  And what about flame resistance, thermal expansion issues, bio-reactivity.  Another thought which might cross ones' mind, is using concrete or bitumen, but these solutions are plagued by thermal expansion issues and other problems, for example - bitumen is known to contain carcinogens, and jointed structural concrete is probably the most expensive solution going.  One might imagine spraying fibrous cement straight onto the ground and even perhaps combining a trowel with the spray head to create a smooth service, but think of the scale of what is called for here - a roof installation covering tens of square kilometers - a man with a trowel or even an army of them makes no difference for it is a big job that can’t be done in some higedy-pigedy fashion.

The ZHR is formed using a novel tension truss which is drawn tight across arched and or sloped ground.  Batons are secured to the trusses, and roof sheets overlaid and fastened in the conventional manner.  The tension trusses are secured to stays which are anchored into the ground, and they are drawn and held tight between the stays so as to carry the batons and sheeting.  A number of risers are placed along the length of the truss so as to hold the truss off the underlying ground and to optimise the roof shape.  A small load pad may be provided for each riser to bear upon if desired, however, use of riser mechanisms which are stapled to the ground or then employ auger screw techniques are contemplated in certain applications.

The ZHR is a green solution of significance.  One may question covering ground so it can be cropped for rainwater, but let one also contemplate the monoculture of a wheat paddock which is surely a very close analogy in every respect.  With ZHR, Australia now has the means to produce large scale artificial catchments in high rainfall areas and to contain the harvested water in high altitude dams which have only a fraction of the impact of conventional dams on the environment.  The conventional dam is constructed across a mature river within the floor of a valley system which results in large surface area and shallow dams.  Many conventional dams therefore struggle with issues around evaporation.  ZHR collects every drop which falls on it, the ZHR even collects frost and dew.  The technology includes the metered injection of sufficient water into the ground underlying the roof to maintain its normal hydrological functionality.  Where a ZHR installation overlays a riparian environment it is possible to build into the system means by which, at least to the riparian environment, it was as if the ZHR were not there, because water discharge into the riparian environment from the ZHR could be managed such as to truly mimic the performance of the underlying ground - the rest of the rainwater harvested by the roof piped away to a holding facility or dam laying somewhat downhill.

We like to say the ZHR is a river in a can.  In far north east NSW there are locations suitable for ZHR which would yield more than 4GL per 100 hectares.  10,000 hectares of ZHR in that corner, perhaps shared with Queensland, would put to rest many of the water pressures expected to mount on businesses and communities in those regions over coming decades.  In far north Queensland, Katter country, there is in excess of 10,000mm p.a. rainfall, that is, 10 GL per 100 hectares available to harvest - a 10,000 hectare ZHR situated there would yield more than 1000GL of clean fresh rainwater never having touched the ground.  Victorias' southern alpine ranges receive an average of 2200mm p.a. and so it is easy to conceive, is it not, that there would be some scope to include ZHR facilities in the upper lesser valleys of those ranges to harvest rainwater there at the rate of 2.2GL per 100 hectares.  The high altitude dams accompanying the ZHR system provide the head pressure needed to gravity feed piped distribution networks below the dam wall.  This means that users from the wall down have access to mains pressure water.

By installing man-made catchments in the form of ZHR in advantageous locations along the Great Dividing Range, and then piping at least some of the water captured there onto the western side of the Divide, the pressure can be taken off the Murray Darling Basin.  Existing catchments can be partially reforested and the western watersheds rebuilt.  We face a series of interconnected crises.  We have need to reduce our groundwater extractions and our river offtakes to begin to rebuild the aquifers and the environments of our wetlands and rivers.  Our towns and cities to the west of the Divide are growing, and the needs of business and the swelling populations are in a hardening competition with farmers and miners for every drop left to get.  We need new water - water which is nowhere unless we do something to capture it.  In many instances the installation of a ZHR facility will be in a locale having less than 5% total annual rainfall run off, 95% is simply evaporated and transporated by plants back up into the atmosphere.

A gigalitre is simply a square kilometre (100 hectares) covered in a metre of water.  The Sydney Basin for example receives on average 1280mm p.a. being equal to 1.28 Gigalitres per 100 hectares p.a.  The entire length of the east coast of Australia receives generally at least this much rain per year.  On these numbers the Zero Height Roof is able to beat the installation and delivery costs of desalination hands down.  We as a nation should consider rejecting wholesale desalination and in so doing send a signal to the world that there is a far greener alternative - the Zero Height Roof.  There is scope over the next few decades for at least 3 million hectares (150 X 200 km) of Zero Height Roof to be installed in locations around the world to meet growing global water needs.

A total of 5,000 hectares of ZHR sited in the Blue Mountains behind Sydney where average annual rainfall is 1450mm would supply the city with 73.5GL p.a.  The build cost for such an installation would be $50 per m2.  If the Federal Government were to provide a 50% grant to those erecting ZHR facilities the remaining 50% of costs could be bourne by the user at less than $2.00 per kilolitre.  Australian Governments, whether State or Federal, have the financial capacity to purchase 'river in a can' ZHR facilities, couple them with high altitude dams, and thereby transform the terms of the Great Australian Water Security and Climate Debate.  With ZHR it is possible to provide both sides of the Dividing Range with the water needed to drought-proof and build our agricultural base, accommodate our population growth, reforest our slopes and plains, and underwrite increased environmental flow allocations to our rivers and wetlands.

With 10,000 hectares of ZHR installed in the Blue Mountains and producing 145gL p.a.  The NSW Government would have the water it needs to open up a growth corridor from Lithgow through Bathurst to Orange and meet at least some of the ever growing water needs of Sydney.  The local environment extending from Lithgow to Orange could be supported and its diversity managed more effectively if there was a ready source of pressurised water to hand - and ZHR is the only way by which to bring genuinely new water to Bathurst and Orange and beyond.  This same solution can be applied in locations along the length of the entire Dividing Range.  Regional Australia needs to hear about ZHR and how it can transform their prospects, lives and communities.  ZHR is nation building infrastructure.  With it we can start to take real action on climate change without destroying our regions.  It is humanity taking responsibility for providing for itself the water it needs to thrive.

Conventional catchments typically evapo-transpirate away up to 95% - 98% of annual precipitation before it can ever reach the water table or the confines of a conventional dam.  ZHR on the other hand, converts all precipitation, even frost and dew, into water yield, and therefore even in the worst of droughts, with a rainfall decline of 50%, the affected ZHR will continue to capture 100% of the 50% that does fall on it - the ZHR is therefore drought resistant in its functionality.

Environmental Impact

ZHR does not require an ongoing supply of energy to operate, and therefore costs almost nothing to run.  It has a small physical footprint, a low visual profile.  It is substantially chemically inert and also substantially proof against fire, flood, tempest, earthquake, vermin and wear.  It can support reforestation by taking pressure off existing catchments, and if it is built at altitude with holding facilities nearby, it can pressure feed, by gravity, all that lays within practicable reach below.  Natural run-off rates where the technology is to be sited are typically less than 5% of annual rainfall, and if it is environmentally significant that the natural run-off response need be mimicked in order to sustain a particular ecological community, the environmental discharge required is not of an order likely to threaten a projects basic viability.  The ZHR therefore need not affect in any measurable way the periodic flows of a given environment downstream of it.  In fact the use of ZHR presents opportunity to better manage the downstream environment in the face of growing climatic variability.  Additionally, with so much water at foot the ZHR presents a coherent design platform for the piggybacking on of solar thermal heating solutions of commercial scale.  The ZHR covers land and in so doing fallowing it for that period of time it endures.  But a 100 hectare ZHR can support the drip irrigation of 5,000 - 10,000 hectares of native seedlings through the critical first years of their plantings.  By combining the ZHR concept with high altitude dams, a powerful environmental tool is formed which can then be used to rebuild and take pressure off the environment.  Everything below the dam wall can be pressure fed by gravity alone.  With ZHR and high altitude dams, the downstream farmer will no longer need to consume energy to provide the water pressure for his irrigation system because he will be able to rely on mains pressure supply.

ZHR

The ultra low profile of ZHR results in low visibility and very high wind strength.

ZHR

The ultra low profile of ZHR results in low visibility and very high wind strength.

Sydney ZHR

A ZHR atop the Blue Mountains can provide a lifeline to Sydney and the population centres west of the range with all the water they need.  What is more, the chosen sites' elevation relative to Warragamba Dam and the proximity of Lake Oberon and similar but as yet unused landforms nearby can be harnessed to create an emergency hydro-electric recharge pumping reserve producing 300MWh which would provide a crucial missing link for the implementation and economic feasibility of green power production across the State.

A ZHR atop the Blue Mountains, this is a South-East looking view, showing 2 highlighted independent sites.

Tamworth ZHR

We propose the construction of a trial ZHR facility of 100 or less hectares in the high rainfall area above the present Dungowan Dam.  The image immediately below shows a trial 100 hectare ZHR proposal for the cities of Tamworth and Gunnedah which would yield an average of 1.25gL p.a.

Tamworth ZHR Site

This image shows a close-up view of the 100 hectare proposal for the cities of Tamworth and Gunnedah which would yield 1.25gL p.a.