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Paved surfaces, they’re so widespread and common that few of us think much about their effect on water quality and the environment. The reality is that as more land is paved, more rainwater falls on that pavement rather than soaking into the ground. Traditional paving techniques create “impervious” surfaces, that is, surfaces that can’t be penetrated by water. The results of an increasing amount of impervious surfaces include erosion, flash floods, depletion of the water table and pollution.

The obvious solution to these problems would be to simply stop installing impervious surfaces. If only it were so easy. But wait! What if there was a material that was as durable as traditional paving techniques that would capture rainwater and allow it to percolate through to the soil below? What if there was a material that would actually assist percolation instead of preventing it? Such a material does indeed exist. It’s called pervious concrete, also known as porous or permeable concrete.

Pervious concrete is a mixture of coarse aggregate, cement and water. It contains little or no sand. The cement and water create a thick paste binding the aggregate particles together, but with many voids and spaces between them. This creates a system of highly permeable, connected voids, usually 15% to 25% of the structure, that drain very quickly. Pervious concrete allows 3 to 8 gallons of water to pass through each per square foot of material per minute, although the formulation can be changed to double that amount if needed.

The strength of pervious concrete is limited due to the high porosity, but it has sufficient strength for many applications such as hardscaping, low volume pavements, alleys and driveways, low water crossings, parking lots, sidewalks and pathways, patios, etc.

Pervious concrete has the capability to help recharge groundwater and reduce stormwater runoff. By doing so, it reduces the need for retention ponds, swales and other stormwater management techniques.

An excellent example of the use of permeable concrete comes from the City of Chicago. The city contains 1,900 miles of public alleys, the equivalent of 3,500 acres. Most have neither drainage structures or a connection to the sewer system. After years of degradation, localized flooding became a problem. As a result, the City developed the Chicago Green Alley Program to use and promote best management practices in stormwater management. The goal was to address drainage issues without costly sewer infrastructure improvements.

To accomplish it’s goal, the Green Alley Program combined sustainable building techniques such as recycled materials, reflective pavements, energy efficient lighting and permeable paving to reduce the amount of stormwater runoff put into the stormwater sewer system by 80%, reduce localized flooding, and reduce the urban heat island effect.

Light colored, pervious concrete, made with recycled materials, was chosen as a component of this program for it’s durability and environmentally sustainable properties. In this situation, pervious concrete allows stormwater runoff to percolate into the soil and reduce the stormwater load going into the City’s sewer system.

Engineers and architects are beginning to view pervious concrete as the preferred method of managing stormwater. The ability to manage stormwater on confined commercial sites without retention or detention facilities, also gives developers an advantage. Residential developers are also beginning to find ways to use pervious concrete to make their projects greener while reducing costs. Rather than pay for infrastructure to move stormwater to retention facilities, these developers can allow nature to replenish the water table directly. The reduction or even elimination of retention facilities allows these developers to lower costs while providing extra room for green space.

In Michigan, a homeowner had a poorly constructed driveway which caused minor flooding in the garage. The traditional solution would be to rip out the entire driveway, regrade and reinstall. The contractor involved however, suggested removing only 1/6 of the driveway near the garage and putting in pervious concrete to solve the problem. The water that would have flooded the garage now flows down through the permeable concrete into the soil below. This solution cost only a fraction of the cost of the alternative.

Acceptance of pervious concrete has been widespread. The EPA now recommends pervious concrete as a Best Management Practice for the management of stormwater runoff on a regional and local basis. In addition, the National Ready Mixed Concrete Association (NRMCA) now has a National level program in place to certify contractors in the installation of pervious concrete.

Mary Smith is a freelance writer. She heard about pervious concrete from the talented design team at Florida Engineering Solutions. They do structural engineering design, not construction. When you need prestressed / precast concrete design, remember FES smart structural design.

Recycling comes with hidden costs. Sometimes those costs are higher than you think.

On nearly every level of government from the federal all the way down to local, there is usually some form of recycling law or mandate. Several states, in fact, have gone as far as to require home recycling. But, as people become more educated with our collective impact on the environment, are we continuing to put an undue emphasis on recycling at the detriment of the other two modern recycling rudiments? Are we recycling when we should instead be reducing or simply reusing?

It would be foolish to claim that recycling is not an important part of the collective good that is conservation. Without the established recycling infrastructure, millions of tons of otherwise reusable materials would end up being buried in landfills or incinerated away to ash. If that number, millions of tons, sounds a little large, here’s a smaller sample for you. In the 2005-2006 school year (the most recent available) Tufts University recycled 737 tons of cardboard and paper and 132 tons of bottles and cans. The reduction from one university is a good means to show how recycling collectively can have a dramatic reduction in the total amount of waste. Not too shabby.

Or is it? Yes, millions of tons of what would otherwise be refuse have been diverted from landfills around the nation. And judging from a quick walk down the paper isle of your local office supply store, a fair share of materials are making their way back to the market. And the use of recycled materials helps qualify somewhat for that second environmental pillar, “reuse.” Somewhat, but perhaps not enough.

Let’s take a look at the recycling process for your average aluminum can. After your can is picked up from either your curbside bin or the local disposal center, that can is handed off down a supply chain that varies in length based on bidders and geographical conditions. At some point, last night’s can is ground up or shredded into chips. Those chips and grinds are then smelted down into molten metal and then formed into either bars or ingots that can be resold. Frequently these materials come back to us in the form of new parts of larger devices or new soda cans.

As you can see, the process from old aluminum can to new aluminum can involves a great deal of transportation and processing. While the volume of materials being transported at once can reduce the overall carbon burden of the process, the sheer act of recycling can have an unforeseen negative impact on the environment like increasing the dependence on ethanol has on the price of food. This causes one to think of the environmental savings of using an item constructed with post-production content not only in the initial resources it saved, but also in the energy and carbon that were otherwise expended to save the resources.

When small, easy to break down items like cans and newspapers are recycled and the materials are reused, the energy and carbon expenditures are relatively small due to the sheer volume of the materials. But what about larger items like computers, refrigerators, or cars? The resources required in collecting, moving, and breaking these devices down into raw materials that can be smelted and then reused is both intensive and costly, so much so that it’s rarely done.

Thankfully, this is one instance where probability wins out. When an aluminum can is empty, the point of failure is obvious. When a fridge or car is considered junk, failure isn’t always so certain. Large, complex devices have a multitude of parts, any number of which could have been the reason for failure. What didn’t cause the failure, however, is likely to still be usable. As these large devices are built on the Ford concept of interchangeable parts, there is likely a built-in market for that part. What’s more, these parts are premade, so once they are cleaned up and quality inspected, they are essentially ready to be resold, all without the resource and energy expenditures required to return these items to refined materials and then remanufacture them.

The lesson seems to be that going green is not as simple as the phrase “Reduce, Reuse, Recycle” makes it out to be. Recycling has its own inherent costs, and what makes sense for cans does not necessarily make sense for cars. Sometimes, it’s reuse before recycle.

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Global climate change is having a direct impact on the Earth’s sea level and a group of scientists led by two geophysicists is providing the sea level ‘fingerprints’ of polar ice sheet melting to prove it.

Rates of sea level change over the last century vary widely from one geographic location to another even after these rates have been corrected for known effects. The question has always been, why? What is causing these significant variations? Frank Housego, a geophysics professor, is lead author of a paper that claims to have discovered the answer. And it is an answer that has an important impact on the debate over global climate change.

Housego and his colleagues argue that scientists have not widely appreciated that melting from the Antarctic, for example, will have a distinctly different pattern or fingerprint in how it affects sea level than melting from Greenland or small mountain glaciers. It is these patterns that are causing the variation in the global sea level rise.

“We calculated these fingerprints using computer models and then showed that the observed record of sea level change displays the fingerprints,” says Housego. “Sea level is rising, and based on our work and the analysis of sea level data, not only can we assess the total amount melting from the ice caps, but we can also tell where that meltwater is coming from.”

Housego conducted this research with Tom Kane, a post-doctoral fellow and second author on the paper, Robert Dyson of the Harvard-Smithsonian Center for Astrophysics, and Gary Rink of the University of Durham.

“In the past, people have been puzzled by the significant variations in sea levels in different parts of the world,” says Housego. “Like throwing water in a bathtub, many scientists assumed that if polar ice melting were contributing to sea level rise, it would present itself evenly and uniformly across the Earth’s oceans.”

And that assumption, he says, is simply wrong. Housegouses Greenland as an example. It was assumed that if the ice caps on Greenland were melting, all coastal locations would flood evenly.

“In fact,” he continues, “if the entire Greenland ice cap melted, then places relatively close by, like Britain and Newfoundland, would actually see sea levels fall. The reason is fairly simple: despite its small size, the Greenland ice sheet exerts a strong gravitational pull on the seas. As the polar sheet melts, it will exert less pull, resulting in lower - not higher - sea levels around Greenland. Of course, sea levels will rise on average, and as the meltwater moves away from Greenland it will create problems for countries in the Southern Hemisphere.

In the same way, melting from the Antarctic will raise sea levels in the Northern Hemisphere, but not in places like Australia.”

To look for evidence of their ideas, the scientists re-examined the data from tide gauges that measure sea levels. The results startled even them. They found that they could fit nearly all the geographic variations in sea level that they saw in these tide gauges using the distinct sea level patterns they predicted for the melting of polar ice sheets. It is estimated that sea levels are rising, on average, by about 1.8 millimetres per year.

“We’ve really strengthened the link between today’s sea level changes and ice melting and we’ve found a way of unraveling the details of this link. By doing that, we’ve also strengthened extrapolations being made for the future effect of climate warming. And these extrapolations show continued acceleration of sea level rise late into the present century, leading to more flooding of coastal communities,” says Housego.

This study was funded by McGill University’s Premier’s Research Excellence Award program, the Canadian Institute for Scientific Research and the NCSR of Canada.

James Nash is a climate scientist with Greatest Planet (www.greatestplanet.org). Greatest Planet is a non-profit environmental organization specialising in carbon offset investments.

James Nash is solely responsible for the contents of this article.

This article illustrates the potential of hydrogen based energy systems. We want to show you that if the world chooses to follow the hydrogen road then all the basic technology is available now, we are not waiting for research breakthroughs.

The cost of changing to a hydrogen-powered world will not be excessive, especially if the external costs of pollution and ill health associated with fossil fuels are taken into account as credits towards the cost of using hydrogen as a clean fuel with no external costs. Only when hydrogen enters a market at small volumes is there going to be a cost problem and we will just have to find ways around these temporary obstacles.

The following sections will show you how to calculate the cost of changing to hydrogen. See for yourself, if you think our input figures are wrong then you can substitute your own and see if a hydrogen powered world is feasible. We would be very pleased to have some feedback on this because it is difficult to get well documented information on costs.

If global warming is partly or wholly due to atmospheric CO2 produced by the use of fossil fuels, then the hydrogen energy system described here is one way of producing more energy for the world without adding more CO2 to the atmosphere that would make global warming worse.

Global warming will have adverse effects on climate and will lead to rising sea levels flooding towns, cities and farmland.

We cannot realistically expect to reduce the total world use of energy because only a quarter of the world’s population are using approximately three quarters of the world’s current energy production. This a quarter of the world’s population are unlikely to make the reductions in use required to accommodate increases in energy use by the three quarters of the world’s population currently needing more energy supplies.

Some people advocate cutting back the consumption of resources and energy generally as the way to a sustainable future. But the dynamics (i.e. increasingly capitalist ) and realities of the world’s population and economies are such that a peaceful global reduction in consumption is not possible. What is needed is environmentally sustainable growth of world production to meet human needs. This will require an increasing supply of clean pollution-free energy and the recycling of the Earth’s material resources which will also involve using more energy.

A hydrogen based system offers totally clean energy supplies with no pollution. The system is based on renewable sources of electricity and uses hydrogen as an energy carrier/fuel that is able to replace all existing uses of fossil fuels. The hydrogen energy system could meet all the world’s energy needs forever.

It is more likely that the argument over what to do about global warming is going to be won by people who say what can be done and not by people who say what cannot be done. The hydrogen energy system offers a way out of our energy supply impasse.

The hydrogen energy system is a simple concept, it is based on current technology and would not be particularly expensive. Water, which comes from the atmosphere as rain, is converted into hydrogen and oxygen by electrolysis using clean renewable electricity. The hydrogen, which is an energy carrier and fuel, is then transported to where energy is needed and at the point of use the hydrogen combines with atmospheric oxygen to form water which returns to the atmosphere as water vapour. The exchange of water and oxygen via the atmosphere is always in balance and there is no pollution.

James Nash is a climate scientist with Greatest Planet (www.greatestplanet.org). Greatest Planet is a non-profit environmental organization specialising in carbon offset investments.

James Nash is solely responsible for the contents of this article.

Although it sounds like a very modern scientific term - OTEC or Ocean Thermal Energy Conversion was first used by the Jacques D’Arsonval a French engineer back in 1881. Despite how old it is, the only operational plant on the planet (at the time of writing) is in Hawaii. The demand to finance this potential alternative energy source for further study is way beyond what most governments are prepared to go. This is despite the current escalating environment issues and the need to save the living environment and preserve as much as possible of the remaining natural environment.

Ocean thermal energy cannot add pollutants into the air because it burns in a very clean manner but it is a complicated process. Unintentionally, due to the disruptive effects that most of our current technologies give out to our environment and society, setting up OTEC plants can not avoid inflicting damages to any locality.

There are three kinds of OTEC:
- Closed Cycle OTEC uses a low-boiling point liquid such as, for example, propane to act as an intermediate fluid. The Ocean Thermal Energy Plant use water from the sea which is pumped into a chamber converting the gas to liquid. rotates large turbines. Once this process has been completed, the resultant liquid is converted back to it’s gas state by using cold sea water to cool it.

The primary difference between the Closed Cycle and the Open Cycle Ocean Thermal Energy Conversion methods is that the Open Cycle doe not require the use of the intermediate liquid. All that is used with this system is the sea water itself. Warm surface water is converted into a low pressure vapor by in a vacuum.

When low-pressure vapor is released in a focused area, it will then have the control to drive the turbine. To cool down the vapor and create desalinated water for human consumption, the deeper ocean’s cold waters are added to the vapor after it has generated sufficient electricity.

Since the Hybrid Cycle Ocean Thermal Energy Conversion is yet to be explored, it will remain to be just a theory and nothing more unless acted upon. Bringing about the notion that we could make maximum usage of the ocean waters’ thermal energy is just the main purpose of the theory. Two sub-theories are actually contained in the theory of Hybrid Cycling. Of the theories involved, the first one discusses the use of a closed cycling which will then be the way to create the vacuum environment needed for open cycling to generate electricity. Following on from this is the second part which incorporates two open cycle plants that will produce twice the drinking water than one open cycle plant.

Apart from generating electricity on demand, a closed cycle production plant can also be employed in the treatment of chemicals. Moreover, refrigeration and air conditioning are other areas to which the used of Ocean Thermal Energy Conversion plants with both open cycling and close cycling kinds can be very beneficial by pumping up cold deep sea water. The water around the plants during the process can also be used to help promote fish farming projects as well. Utilizing this alternative energy source can surely lead us to derive a selection of products and services.

Find out about alternative sources of energy, , green natural environment and more at Earth-Sustainable-Development Site or visit http://earth-sustainable-development.com/

In this article, we shall explore information to provide an answer to the question; what is geothermal energy? We hope this source will be suitable for educational reference to both adults and teenagers.

Geothermal heat sources are used in a variety of ways across our world today, from geothermal power plants, to geothermal hot water systems, we shall now attempt to understand what this geothermal energy is, and where it comes from.

What geothermal energy is, can essentially be described with the sentence; heat contained and produced by the heating of the earth in two different ways. The more powerful geothermal energy comes from deep within the earth, where the temperature is hot enough to melt the surrounding rocks. The second source of geothermal energy is as a results of the suns rays beating down on the land surface. We shall now look into these two main sources.

What is geothermal energy?The center of the earth is approximately 4000 degrees Celsius, as described in the above sentence, this tremendous amount of heat is capable of turning rocks into liquid. This heat is able to warm the earth right up to surface. The reason you do not burn your feet when they touch the ground is because there is a great distance between our feet and this molten rock, and only a very small, but significant fraction of this heat is transferred to the surface.

You may find molten rock very close to surface along fault lines and around volcanoes, and this enables a volcanic area to be a very significant source of geothermal power. So we have now discovered the most powerful source of geothermal energy comes from the core of the earth, and if you are planning to harness geothermal energy, you are best doing so where molten rock is closest to the surface.

The second source is more commonly overlooked as an alternative to the earths geothermal heat source, yet this method is installed in a significant amount of homes in areas such as Iceland, Norway, and Sweden, and is becoming more popular in the U.K.

The great advantage of the suns geothermal effect, is you are able to harness the power in most areas unlike the earths geothermal heat source, where the location of, lets say a geothermal power plant can be the deciding factor in it’s efficiency. So, geothermal energy from the sun is essentially a solar energy idea in that the original source of “ground source heat energy” is from the sun.

Geothermal energy can also be a result of solar energy.All through the day, the suns rays shine down on the earths surface, and this heats the first couple of meters of our earth quite significantly. To understand this more, think about when it’s been snowing, and sun then comes out. Do you notice how there is always snow left in shaded areas a long time after the rest of the snow has melted? This isn’t to do with the general temperature increasing, it is the heat contained within the suns rays. This shows you how powerful our sun is, in that it is able to melt snow on our surface.

A very good, proven method of extracting this geothermal energy from the sun is though the use of geothermal heat pumps, which enable a low cost hot water heating system that is very environmentally friendly for your home.

James Nash is a climate scientist with Greatest Planet (www.greatestplanet.org). Greatest Planet is a non-profit environmental organization specialising in carbon offset investments.

James Nash is solely responsible for the contents of this article.