Sequestration in the Built Environment

Fossil fuels are the main source of energy around the world and much as alternatives may be desirable, decoupling the economy too rapidly without alternative sources of energy could result in mayhem (see our Economics and Political Analysis pages). In spite of all the talk about a carbon constrained economy, it is important to recognize that the use of fossil fuels per se is not the problem, it is that over the last two centuries the level of CO2 in the air has risen around 35% and this is causing climate and environmental change that will not be easy to reverse. Surviving the future requires massive sequestration and for implemention to occur on the required scales the processes adopted must be profitable. See The Implications of Gaia Engineering for the Cement and Concrete Industry

Even if the use of fossil fuels could be curtailed in favour of alternatives this would take many years and so the overriding objective for climate and environmental security must include as a high priority getting the CO2 out of the air. To do this we have to change the technical paradigms which are the basis of the physical side of our economy (our techno-process) and TecEco and other members of the Global Sustainability Alliance uniquely advocate a paradigm in which we profitably store man made carbonate as building materials. A calculation as to the amount required is to be found at Carbon Cycles and Sinks. A model comparing this solution to geosequestration and that approaches the numbers from the direction of need thereby confirming them is to be found in the TecEco downloads area.

James Watt invented the steam engine and this used coal. Somebody else came along and said oil is better because you can carry it about in a barrel. A few thousand inventions later and you have the well developed techno-process that now dominates our lives, our landscape and unfortunately our planet and that is powered by fossil fuels. We have developed a techno-process of immense proportion.

Underlying the flow of all the materials that are involved are economic flows of molecules ( moleconomic flows) in the global commons that are damaging to everything that lives in our biosphere and upsetting flows in the geosphere. To mention but a few; heavy metals, CFC's and of course CO2 in the air. We are choking and poisoning ourselves - slowly. It's a bit like the old agar dish experiment from biology at school - remember how it works? You put a spec of bacteria in the middle of a food supply loaded in agar jelly and behold - the bacteria grows in a ring to the edge of the dish dying in the middle as the poisons in its world (the dish) kill it. There is no escape.

How can we avoid this fate? Fortunately the world is a big place and there are externals not present in the agar dish. Winds, tides and currents circulate nutrients like oxygen, microscopic food in the sea and take a way wastes. We used to live in a balanced ecological system where supply and demand were as in a stable economy balanced. We are alive because in natural systems that are in equilibrium there is little waste, or poison. Everything that is produced naturally is used naturally. That is until we came along with our machines with their appetite for fossil fuels and threw the whole lot of balance.

Vehicles, power stations and so on use fossil fuels and are upsetting our global carbon balance. We have used up over half of the last few billion years worth of carbon stored by nature in the form of petroleum, and a somewhat lower proportion of the total coal.

Even if we were to convert all our cars to non fossil fuel, master fusion reactions and shut down our coal fired power stations it would take hundreds of years for global warming to reverse because CO2 in the atmosphere has a residence time of around 50 - 200 years[1] and there is a marked lag between emissions and warming.

How can we turn this juggernaut of such immense proportions around?

The current strategy adopted by most countries is not holistic, is insufficiently broad based and will not work. Given human nature massive emissions reduction in the order of 30-80% being discussed by politicians is not going to be achievable without either alternatives, carbon rationing or both and that may lead to more conflict that is predicted to occur as a result of global warming. So called clean coal at this point in time is an oxymoron. Coal is the dirtiest burning of all fuels and geosequestration which involves burying carbon dioxide in our leaky old earth still has technical problems, is costly and fraught with danger for future generations. See The Implications of Gaia Engineering for the Cement and Concrete Industry. Weaning ourselves from fossil fuels and learning how to use the flux of energy coming from other sources is important but even though these energies are of immense proportions and everywhere[2] they are hard to capture and it will take time to develop the technology platforms required. Besides there is immense investment in the coal and oil supply chain that would rapidly sink world economies if too rapidly unwound.

A more holistic approach would disclose the obvious. We must find ways of profitably getting the CO2 out of the air as well as reducing the rate at which we are putting it there. These ways will not be effective unless everybody everywhere is using them so they should be profitable. They have to produce real tangible benefits that satisfy human survival instincts because human beings can never be expected to do anything just because it is the right thing to do. That should be the responsibility of governments. Unfortunately however governments are only elected for a few years and the politicians and others involved are driven not so much by statesmanship but by the need to keep their jobs! The problem of externalities such as emissions discussed by Aristotle and Plato continues.

We have no choice but to change the technical paradigms which are the basis of our techno-process. We must do things differently. Pilzer's first law predicts that changing the technical paradigms will change resource flows[3] and thus underlying moleconomic flows in our techno-process. We could if we wanted to hard enough actually reverse the flow of CO2 into the atmosphere. It is a matter of changing the flows in our techno-process and redefining CO2 as a resource.

A technical revolution the size of the one started by James Watt is required. The Global Sustainability Alliance offer Gaia Engineering which, focusing on the major materials flows in the built environment[4] because of their size. Gaia Engineering, is a tececology that is big enough to reverse global warming. In nature CO2 is used to create the homes of the vast proportion of plants and animals. Realistically to save our civilisation we have to do the same and find ways of incorporating carbon into our built environment. Gaia Engineering mimics nature, providing a cost effective way of using the built environment as a repository for carbon dioxide and waste.

Using man made carbonate aggregate with TecEco Eco-Cement made using Tec-Kiln technologies without releases we can change global carbon flows as in the diagram below.

The Carbon Cycle Modified by Gaia Engineering

By using carbon dioxide to build our homes just like shellfish and trees do the Gaia Engineering tececology is geo-biomimetric. Like a giant ecological pump the technology works to reverse the problems of global warming and waste.

Magnesium oxide-hydroxide-carbonate systems are favoured by Gaia Engineering because magnesium has a low molecular weight and bonding with significant amounts of CO2 [5] ; its oxide is easy to make using our Tec-Kiln technology without releases and provided it is reactive enough magnesium oxide hydrates quickly in a hydraulic mix and given exposure to air the hydroxide will carbonate readily. Magnesium is abundant in the ocean and brines and water containing magnesium is a resource of every country on earth. Driving the magnesium thermodynamic cycle to carbonates or even a complete cycle to sequester CO2 does not take huge amounts of energy and can generally occur at low temperatures using non fossil fuel sources.

The Magnesium Thermodynamic Cycle

In Gaia Engineering the magnesium comes from sea water or brines and is precipitated as carbonate in a front end process such as Greensols. The overall process will be economic because other valuable minerals and fresh water are produced as by products. Some of these precipitated carbonates will be used as building components such as aggregate for constructing the built environment and the remainder used to make a binder to hold these components together. TecEco's solution is magnesium Eco-Cement made without releases to the atmosphere using its Tec-Kiln.

The important rquirements for the carbonation of Eco-Cement are gas permeability and adsorbed water for through solution reaction. First magnesium hydroxide forms which under these conditions carbonates forming nesquehonite and other magnesium carbonates (many of which are also hydrated further adding to the volume of material produced). TecEco have demonstrated that carbonate binders work, are achievable relatively easily and sufficiently rapidly. People have been using mined carbonates such as magnesite, dolomite and limestone for years to build with. The switch to man made carbonate is no giant leap of faith and is the most logical solution. With capture of CO2 during manufacture as proposed by TecEco using it proprietary Tec-Kiln and substitution of major flows in the built environment such as that of concrete with carbonate based materials, sequestration on a massive scale is possible.

As stated by Fred Pearce in the article on Eco-Cements published in the New Scientist magazine (Pearce 2002[6] ) “There is a way to make our city streets as green as the Amazon Forest. Almost every aspect of the built environment from bridges to factories to tower blocks, and from roads to sea walls, could be turned into structures that soak up carbon dioxide – the main greenhouse gas behind global warming. All we need to do it is the change the way we make cement.”

Sequestration With and Without Capture of CO2 during the manufacture of Eco-Cements

For a well balanced strategy to save our civilisation from global warming we believe it essential to also instigate a plan to reverse the flow of CO2 in our techno-process using the Gaia Engineering tececology. Humans, rats, fleas and cockroaches will not notice the difference with a shift to using man made carbonate, it could even be cheaper. Most importantly doing so will save our climate. There is no need to fear the change as economic history demonstrates clearly that change, properly managed stimulates economies.

With the capture of CO2 during the manufacture of Eco-Cement and using carbonate aggregates from for example the Greensols process the sequestration potential is enormous and pales into insignificance other sequestration solutions most of which are wacky science and leave legacies for future generations to deal with. See Solutions to the Global Warming Problem Wacky or Otherwise. TecEco have developed an LCA model for its Eco-Cement which is downloadable from the web site that is a useful tool to demonstrate exactly how much CO2 could be sequestered by its cements. Using building components that are solid carbonate will sequester much more - Just how much is calculated on our Carbon cycles and Sinks page. Also on the web is a spreadsheet tool for comparing sequestration in the built environment as building materials with geosequestration.

TecEco Cement LCA

Gaia Engineering v Geosequestration

Using our LCA model it is possible to model the emissions or sequestration of TecEco cements with or without capture of CO2 and switch other variables. With carbon capture during manufacture net sequestration is potentially significant in eco-Cements as in the following diagram.

Using our spreadsheet tool it is easy to compare sequestration of carbonate as building material (Gaia Engineering) with geosequestration.

Sequestration Using Eco-Cement Calculated with Carbon Capture

Many scientists think that we have a ten year window to turn global warming around. Even if they are all wrong it makes sense to move towards sustainability just in case.

We demonstrate on our Economics and Political Analysis page that it will not be possible to decouple the economy from fossil fuels quickly, indeed many think that coal will be our main source of energy for years to come and that nuclear carries with it too high a risk of proliferation. (Lackner et. al.[7] ).

Our Gaia Engineering solution involving sequestration of carbon as building materials:

With TecEco's technology we can experience the confidence and security of moving into the future. Implementation would be driven by profit.

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[1] The residence time of CO2 is thought to be between 100 and 200 years, but no range has been agreed to.

[2] Pilzer, P. Z. (1990). Unlimited Wealth - The Theory and Practice of Economic Alchemy, Crown Publishers.

[3] According to Wikipedia solar radiation on average is about 340 W m-2 and tidal energy 0.0059 W m-2

[4] The built environment comprises 70% of materials flows, is made of materials and is our footprint on earth. 40-50% of waste that goes to landfill (15 % of new materials going to site are wasted.) are building materials. Around 50 billion tonnes of building materials are used annually on a world wide basis.

[5] More CO2 is captured using magnesium than calcium as the following calculation using molecular weights shows.

CO2/MgCO3 = 44/84 = 52%, whereas CO2/CaCO3 = 44/101 = 43%

[6] Pearce, F. (2002). "Green Foundations." New Scientist 175(2351): 39-40.

[7] Lackner, K. S., D. P. Butt, et al. Binding Carbon Dioxide in Mineral Form: A Critical Step Towards a Zero-Emission Coal Power Plant. DOE Office of Scientific and Technical Information (OSTI), Los Alamos National Laboratory.