Tag Archives: greenhouse
Straw as Building Material for Future
A modern take on straw-bale construction may well be the grand design of the future if results coming out of the University of Bath are accepted by the construction industry. Think of a straw-bale house and you might imagine a tumbledown shack that leaks, creaks, slumps and smells somewhat of the farmyard. But step into Bale-Haus, a startlingly contemporary looking prototype home that has been built on the Bath Campus and there’s nary a wisp of straw to be seen. Instead, you are in a hallway of an upside down house with two bedrooms and a bathroom on the ground floor and an airy open plan living area upstairs. It feels like a little piece of Scandinavia has just arrived in Somerset, southwest England. The straw bales are all packed tightly inside a series of prefabricated rectangular wooden wall frames, which are then lime rendered, dried and finally slotted together like giant Lego pieces called ModCell panels.
People perceive straw houses as being a bit hippy and not particularly durable. Add to that the problems of getting mortgage – very few lenders will consider straw-bale construction. The benefits of straw, points out Professor Peter Walker, director of the University of Bath’s BRE Centre for Innovative Construction Materials, are that “it’s cheap, widely available and a good insulator. It’s been used in buildings houses for hundreds of years”.
The stack that remains after grain has been harvested – straw also helpfully soaks up carbon from the atmosphere and locks it in, so long as it is not allowed to decompose. For the building industry, which currently depends on materials with very high embedded energy costs - concrete and brick are expensive in carbon terms both to make and to transport – straw could therefore offer a welcome solution to housing’s greenhouse gas emission.
The straw-bale house won’t get sopping wet in a thunderstorm or go up in a whoosh of flames if you knock over a candle. The results now being published by Walker and his research partner, Dr Katharine Beadle, who have spent the past 18 months testing the BaleHaus against an exhaustive list of risk factors that could rot it, burn it or blow it down, so far seem to be reassuring.
Beadle with his team took a ModCell unit to a test laboratory and tried to reduce it to ashes by strapping it to a fiery furnace and raising the temperature to over 1,000 degree Celsius. “It’s standard test to replicate a fire in a building.” explains Walker. “It means you know that a house will at least retain its structural integrity for half an hour, which gives people a chance to get out”. “It took an hour and a half of being in direct contact with the flames”, says Beadle, before the lime render began to drop off, “and then the straw did start to burn back, but because it’s so compacted it suffered more charring then actual disintegration.”
When it come to blowing the house down – hydraulic jacks were placed against the walls to replicate wind forces pushing against the bales – the ModCell panels moved a few millimeters, but stayed within the tolerances allowed for by the computer modeling carried out prior to its construction. That says Walker, could be very good news for the price of the eventual ModCell building system. “It means the house is stiffer than it needs to be.” The approximate cost of the current modular building system for this design is £132,000 from above the concrete slab. “Cost is a challenge to the introduction of this technology but as a prototype house I think it stacks up well,” said Walker. “The aspiration is that it should be cost competitive with more savings coming through reduced heating bills.”
To replicate the heat given off by humans and appliances arrays of incandescent light bulbs on timers blaze in every room at pre-programmed times of day “to see how much heat escapes, and what level of heating would be needed at different times of the year,” explains Beadle.
“That environmental modeling will give us all the numbers about the energy the house is predicted to use. And if we are predicting how it will operate in given climate change, we can then put in those variables.”
Sensors embedded within each wall panel constantly monitor the degree of moisture absorbed and then released back through the breathable lime render into the sir outside by the panels. And on the air tightness test that was carried out, BaleHaus came in way under the building regulations threshold, and did considerably better than the far lowest “best practice” standard.
- The Guardian
How Green Is Hydroelectricity?
Hydroelectricity is often presented as a green energy source, but how true is this? Hydro has several environmental and aesthetic drawbacks that make it less than ideal compared to the clean power provided by sources such as wind and sun.
The most visible environmental aspect of Hydroelectricity is its impact on the environment, as it requires the damming of rivers. This causes the flooding of low lying land behind the dam and while this is often not desirable, the reality is that it is just an alteration to the environment. If the dam was to remain filled with water all the time, this would have no environmental effect outside the dam area.
Why is it then that Hydroelectric installations are associated with high levels of methane production? When organic matter from plants and animals breaks down without oxygen present, methane is formed. This anaerobic process is very similar to the ones that resulted in the formation of the fossil fuels we use today.
Consider the following chain of events that unfold once the dam has been constructed.
First the land is submerged and the vegetation with it. The vegetation drowns and begins to rot. Since there is very little available oxygen, the plant material breaks down to form, among other things, methane that is absorbed by the water.
This is all normal so far, as this would occur with any permanent flooding. But a Hydroelectricity dam is usually both a power supply and an urban water source and so the water levels in the dam tend to rise and fall a great deal. In dry times the water level will drop to its lowest levels which will expose land around the edges of the water and possibly at the bottom of the dam itself.
This exposed land is ideal for growing plants and so it blooms with new life. As most dams are shallow, the amount of land exposed at the edges as the water drops can be very large. The shallower the dam, the more land is exposed annually.
After a time the rains return and the dam fills up again. The new vegetation is then also covered with water and so rots anaerobically and so more methane enters the water of the dam.
This continues year after year, resulting in a slow but steady increase in the amount of methane absorbed in the water of the dam. This is a problem because methane is not very soluble in water. When the water passes through the dam’s turbines it escapes the water and enters the atmosphere.
Methane is a dangerous greenhouse gas. It is approximately 21 times more effective at trapping heat in the atmosphere than Carbon Dioxide. This means that electricity from a Hydroelectric plant can be up to three times more polluting per energy unit than the same power from a coal or oil fired plant. This figure depends on the climate and geography the Hydro plant is located in, as these factors determining the amount of vegetation added to the dam each year. The Intergovernmental Panel on Climate Change (IPCC) has recognized this issue and now includes methane from Hydroelectricity in national emissions totals. 
Hydroelectricity may be a renewable energy source but it is not an environmentally friendly one. When looking at whether a new Hydro plant is warranted, methane emissions must be taken into account. A cleaner and greener solution is to build solar and wind energy stations as once constructed these have no emissions associated with them at all.
For more information on electricity generation and its issues, visit the Fossil Fuels section of Roger Vanderlely’s website. There you can also find out about getting a good deal on cheap solar panels to become more power independent and do your bit for the environment.
This article is brought to you by George Zalcman. George Zalcman has always had a passion for green technologies, and believes that we should all get on the boat before natural resources become limited. George Zalcman is part of an air to water technology hoping that this will eventually bring an end to the water crisis as well.
Conventional farming limits greenhouse gas emissions
Advances in conventional agriculture have dramatically slowed the flow of greenhouse gases into the atmosphere, in part by allowing farmers to grow more food to meet world demand without ploughing up vast tracts of land, a study by three Stanford University researches has found.
The study which has been embraced by many agricultural groups but criticized by some environmentalists, found that improvements in technology, plant varieties and other advances enabled farmers to grow more without a big increase in greenhouse gas releases. Much of the credit goes to eliminating the need to plough more land to plant additional crops.
The study’s authors said they aren’t claiming modern, high production agriculture is without problems, including the potential for soil degradation through intense cultivation and fertilizer runoff that can contaminate fresh water.
But some environmentalists said the study is flawed, arguing it’s based on unrealistic scenarios of what would have happened if yields hadn’t increased during the study period. The yield is the amount of a crop grown per acre. 
The other authors are Jennifer Burney, a physicist who focuses on energy and food security research at Stanford’s Program on Food Security and the Environment, and David Lobell, an assistant professor of environmental science at Stanford who has studied the effects of food and bio-fuel production on the environment.
The three decided to look at the impact of agriculture on greenhouse gases – carbon dioxide, methane and nitrous oxide. Agriculture accounts for about 12 per cent of greenhouse gas emissions generated by human activity.
The researchers set up hypothetical models in which the world’s growing population was fed by cultivating even more land. Those models were then compared with actual agricultural production between 1961 and 2005.
Yields for major crops like corn and soybeans have increased dramatically over the study period. Midwestern corn farmers for instance now average well over 160 bushels an acre. That’s roughly double what they produced in the early 1960s, according to US Department of Agriculture statistics.
Without those increases, it would have taken an additional 4.35 billion acres to feed the world according to the study. The cultivation of that land including the release of carbon in the soil and burning of brush and trees that covered it would have released an additional 317 billion to 590 billion tons of greenhouse gases, the authors wrote.
Average temperature to rise by 4 degree Celsius
The world is heading for an average temperature rise of nearly 4 degree Celsius, according to analysis of national pledges from around the globe. Such a rise would bring a high risk of major extinctions, threats to food supplies and the near total collapse of the huge Greenland ice sheet. More than 100 heads of state agreed in Copenhagen last December to limit the rise in global temperature to 1.5 – 2 degree Celsius above the long term average before the industrial revolution, which kick started a massive global increase in the greenhouse gases blamed for warming the planet and triggering climate change. 
But six months on, a major international effort to monitor the emissions reductions targets of more than 60 countries, including all the major economies, the Climate Interactive Scoreboard, calculates that the world is on course for a rise of nearly double the stated goal by 2100. Another study by Climate Analysts at the Potsdam Institute in Germany suggests there is “virtually no change” world governments will keep the temperature rise below 2 degree Celsius. In the last assessment of the problem in 2007, the Intergovernmental Panel on climate change (IPCC) forecasts that a rise of more than 2 degree Celsius would lead to potential increase in food production, but an increasingly high risk of extinction for 20-30 percent species, severe droughts, floods and a unstoppable “widespread to near total” loss of Greenland ice sheet over very long time periods.
however at 4 degree Celsius it predicted global food production was “very likely” to decrease, “major extinctions around the globe”, and near total loss of Greenland’s ice, precipitating 2-7 meters of sea level rise in the long term. The climate interactive Scoreboard, for which researchers check daily for updates in emissions or other targets which would reduce pollution such as reductions in energy intensity or increase in renewable energy, make a medium-range prediction of a 3.9 degree Celsius increase in temperatures, with a range of 2.3-6.2 degree Celsius, based on committed targets and a more encouraging 2.9 degree Celsius average, with a range of 1.7-4.6 degree Celsius based on “potential” commitments suggested but not enacted by many nations.
Climate Analytics and Ecofys, under the banner of Climate Action Tracker, estimate a range of 2.8-4.3 degree Celsius.
Stopping CO2 emissions cannot avert climate change
With carbon dioxide (CO2) in the air approaching alarming levels, even halting emissions altogether may not be enough to avert catastrophic climate change. A new study by Carnegie institution scientists suggests that while removing excess CO2 would cool the planet, carbon cycle complexities would limit the effectiveness of a one time effort. To keep CO2 at low levels would require a long term commitment spanning decades or even centuries. Previous studies have shown that reducing CO2 emissions to zero would not lead to appreciable cooling because CO2 already within the atmosphere would continue to trap heat. 
For cooling greenhouse gas concentrations need to be reduced. “We want to see what the response will be if carbon dioxide were actively removed from the atmosphere,” says study co-author Ken Caldeira of Carnegie’s Department of Global Ecology. Caldeira and study co-author Long Cao did not focus on any specific method of capturing and storing CO2 from the air. The posibilities include approaches as diverse as industrial scale chemical technologies and changing land use so more CO2 is naturally absorbed by vegetation.
According to the simulations conducted by the researchers, for every 100 billion tonnes of carbon removed from the atmosphere, average global temperature would drop 0.16 degree Celcius, said a Carnegie institution release. Further simulations showed that in order to keep CO2 at low levels, the process of CO2 extraction from the air would have to continue for many decades, and perhaps centuries, after emissions were halted.
International accords on saving forests have little impact
International accords on saving vulnerable forests are having little impact because they do not attack the core causes such as growing demand for bio-fuels and food crops, a new report said.
With Africa and South American alone losing 7.4 million hectares of forest a year, the International Union of Forest Research Organizations (IUFRO) said a drastic change of policy is needed by the United Nations and governments.
Sixty international experts said in the report, to be presented at a UN forum this week that too much attention is being put on forests as a store of carbon dioxide, the main gas blamed for global warming.
Deforestation accounts for about a quarter of the global greenhouse gas emissions each year which are blamed for rising temperatures. Live trees act as a sponge for carbon but give it off when they decay or are burned.
“Our findings suggest that disregarding the impact on forests of sectors such as agriculture and energy will doom any new international efforts to conserve forests and slow climate change,” said Jeremy Rayner chairman of the IUFRO report panel.
Even the most recent UN backed initiative, Reducing Deforestation in Developing countries (REDD) is criticized because the panel said it seeks a single global solution.
The experts said that REDD and other international accords should focus more on supporting regional and national efforts to save the forests at risk.
“Unless all sectors work together to address the impact of global consumption, growing demand for food and bio-fuels, and problems of land scarcity, REDD will fail to arrest environmental degradation and will heighten poverty,” said Constance McDermott of Oxford University’s Environmental Change Institute.
Saving polar bear from extinction
The polar bear can be saved from extinction — but only if action is taken quickly to make deep cuts to greenhouse gas emissions, a new study shows. The study, published on December 15 in journal Nature, conflicts with previous research, which suggested that Arctic temperatures are already on track to exceed the threshold required to trigger rapid, irreversible ice loss.
Researchers from Polar Bears International said sea ice in the Arctic, which polar bears use as a platform on which to hunt seals and breed, is unlikely to undergo a rapid and irreversible decline when temperatures rise beyond a certain threshold. “It’s widely believed that nothing can be done to save the polar bear,” said author Steven Amstrup of Polar Bears International in Winnipeg, Canada. “But that’s not true.”
According to Andrew Derocher, a polar bear expert based at the University of Alberta in Edmonton, Canada who was not involved in the study, Amstrup’s study is the first to assess whether a campaign to slash emissions will benefit polar bears. “Mitigation of carbon emissions was not considered by any of the analyses to date,” he said.
Amstrup’s team used global climate models and five scenarios of the level of greenhouse gas emissions to estimate sea ice loss in the Arctic over the next century. The paper suggests that there will be a linear relationship between temperature and sea ice: as temperatures rise, the amount of sea ice will decline smoothly.
If emissions continue to rise at today’s rate, two-thirds of polar bears will disappear by 2050, the models suggest. Populations in Hudson Bay, Baffin Bay, the Southern Beaufort Sea and Barents Sea will be hit the hardest. In addition, the amount of optimal polar bear habitat in the Arctic will fall by 50 per cent, according to Amstrup. But stringent emissions cuts of 70 per cent by 2100 would limit habitat loss to just 20 per cent — saving the polar bear, says the study.
“Reduced emissions would yield greater abundance and wider distribution of polar bears than the ‘business as usual’ emission scenario,” said Derocher of the paper. Derocher is skeptical that policymakers will act to curb emissions in time. “There are few indications that such policies will be implemented in a timely manner. Globally, 25 percent of mammalian species are threatened with extinction and, in this context, the plight of polar bears is sadly typical,” he said.