I am currently doing a research project on green roofs and am trying to find out different plant intakes of CO2 and what plants consume the most. I am also trying to find out if carbon is stored in plants and what happens to the co2 when the plant dies. ultimately i am trying to sse if green roofs could be a feasible option in reducing co2 in the future. Any help would be awesome. Lewis
In general, you can take the plant and dry it out. The plant that weighs more during the same time will have absorbed more CO2. When the plant dies, bacteria and fungi break down the dead plant and release the carbon back into the air. A green roof will only hold the carbon present in the plants.
If you want to maximise carbon storage, plant fast growing trees. And then watch the roof collapse under the weight of stored carbon ;-)
Hi, for a way out option how about culturing a coccolithophorid micro-alga on your roof. Coccolithophorids sequester some CO2 as calcium carbonate scales - which is a potentially long-term sink (the cretaceous chalk is almost completely made up of these "coccoliths". Coccolithophorids have two other interesting properties: the scales reflect light increasing the albedo and the cells produce compounds related to dimethyl sulphide which act as cloud condensation nucleiincreasing cloud cover. Both these properties should lead to cooling. If cultured in an open tank, water evaporation would also cool the local environment. Most species are marine and an excellent target species would be Pleurochrysis carterae ( see this PhD thesis http://researchrepository.murdoch.edu.au/206/ ) but there is a freshwater species Hymenomonas roseola. One big problem though.....they are brown - not green ! boa sorte! Brian
Plant "mowable" or other harvestable plants. Put the clippings & prunings in a sealed mine shaft so that the CO2 is absorbed into the rock or stays in the sealed atmosphere. ...sounds goofy to me, but there you are. Thats my 2 polysaccharides worth.
Overall -- Not viable as a carbon sink. Suppose you plant it to grass. Grass grows, top winter kills. Gradually builds up a thatch. The bottom of the thatch decomposes. Some of that gets recycled into new grass. Over a very long term, the organic matter in the soil increases, which is a very slow carbon sink, but even that is a matter of a ounces per square foot per century. Forests aren't much better. Instead of taking 2-5 years to get to an equilibrium state (decomposition = growth) it takes a century. All the bio systems that you see are inherently recycling machines. The exceptions are the same processes that originally made coal and oil -- mostly swamps and bogs. Peat bogs are the prime example currently. Because the water moves so slowly (if at all) anything mroe than a few inches down is anerobic, and cold. Also tends to be acidic. Combination taht makes for slow decomposition. Artificial peat bogs may be a good answer for carbon sequesterization.
That's a few of us that seem to have the concept. Very reassuring. Unfortunately there are SO many people out there, including most policitians & bureaucrats who think that short-term fashionable fixes in ever increasing populations & economies are actually long term stable situations. After all, they say, we have proved Malthus wrong haven't we? We are the cleverest things around! Hmm? I suspect that H. sapiens is inaptly named in this regard & that our tenure as the dominant species is going to be very brief.
Climate change is unlikely to mean human extinction. I wouldn't want to have extensive real estate holdings in Bangladesh right now. There are a bunch of islands that are going to disappear too. Coastal real estate is eventually going to get damp. If you look at worst case scenarios (6 degree temperature rises by 2100) there is going to be a LOT of disruption. I suspect that deliberate eco-engineering is going to become THE growth industry. Since the growth zone of many plants is moving north faster than the plants can do so, it will be up to us to help them along. Extinction as a species may not be in the cards, but mass starvation will be, particularly in the third world. Not so much because of higher temperatures, but due to changes in rainfall. We're already seeing instances of this. Twice now, the monsoon has failed in Brazil, leaving rivers of mud and dead fish. Species with narrow ranges of habitat and small distributions are at risk. The next century won't be a permian extinction type event, but it will be 'interesting times' Forestation is a viable way to buy time. Biomass as fuel, won't remove C from the atmosphere but it can reduce the amount of fossil carbon released. I live next to a coal mine + power generation station. They put in a proposal for a carbon extracation/sequesterization pilot plant -- a 300 MW unit that would scavange 85% of the produced CO2, and inject it into deep formations. (10,000 foot) The energy required to separate the CO2 drops the overall plant efficiency by about 10%. Last I heard the pilot project went to the neighboring plant at Keephills. (I live near Genesee) Sequestering CO2 as chalk as an earlier poster brought up is an interesting notion. But that will require a mole of calcium for each one of CO2. That in turn requires getting calcium from some source that isn't carbonate. The only common source I can think of is gypsum -- CaSO4, but I'm not sure if you can come up with an economical solution that involves the net exchange of sulfate for carbonate. Uncommon source are unlikely to be available in the quantities needed. Farming the oceans -- making locations near the equator flourish with algae near places where there are substantial sinks, so that a significant fraction of the plankton get carried down to the abysal deeps may be an option also. While not permanent, we're talking geologic time, not human time. (Or as Greg Bear puts it, "Deep time" -- spans of time longer than human civilization) The down side is that your nutrients get carried down too. Will this happen in the next century? No. The only way to get things to happen is to figure out a way that individuals (corporations) can make money by being green. Economics is a golden corset. Some of this can happen locally by creating economic biases. But world wide action requires either world wide government or economically advantageous solutions. Example: Wind power to *really* win has to be cheaper than just the operating cost of coal. When that happens, you use wind when it's available, burn coal when it's not. If your network is large enough to provide reasonably reliable baseload, then it is sufficient to be cheaper than the operating cost of natural gas. This isn't unreasonable to do, but there will be a LOT more HVDC power lines across the land moving power from windy places, such as north Texas to people places such as the eastern seaboard. High altitude (jet stream) wind is a theoretical possibility. There are some daunting technical challenges to developing it, but the power density is of a scale that the same amount of ground used for coal for the life span of a generation station could provide space for the tethered flying windmills that would produce the same power. All the renewables (sun, wind, water) suffer from episodic delivery, with water being the most reliable generally. If a decently effiicient way to store energy can be developed, a lot of the inefficiencies go away. The ideal storage is cheap, dense, and has easy turn-on/turn-off capability. EEStor claimed a batacitor (battery/capacitor) that could store 50 kwhr in a unit the size of two milk crates. At the time they were trumpeting their news, they figured production costs of $2500 per unit. This, if it were true, would mean taht for 10% of the price of a house, you could store a week's power. In the short run this means that power plants could run at their optimum load rating. In the long run it means that wind power is thrown onto the grid and stuffed into boxes in the basement or garage. Alas eestor has yet to produce a product. More likely is electrical production of methanol. The process, as I recall is about 85% efficient. Now you size your wind power to cover baseload N% of the time, have methanol powered turbines to provide power 100-N% of the time, and sell surplus methanol to the transportation market. Making an auto engine that burns methanol is trivial. (Race cars run on it.) Again, have long distance power lines will make it easier/cheaper to do.
This is an old post, but I find this interesting. There is another advantage to having plants on the roof that is being ignored in this post - typical asphalt shingles (or any other roofing material for that matter) heat up very much and tend to increase the temperature of the environment and the building. Plants convert the energy into food rather than heat. This could also potentially increase the A/C efficiency of the building thereby indirectly decreasing CO2 output. When we first bought our house in 1998 the attic would heat up to 150+ F (I measured it). It was inadequately ventilated. The upstairs was uncomfortably hot unless the A/C was cranked, and the ceiling actually felt very warm as the insulation acted as a heat sink that just kept giving off heat throughout the night. We fixed the problem in 1999 by adding massive attic vents. Now the temperature differential is only a degree or two between the downstairs and upstairs (it was about 8 degrees F before). This problem is endemic as builders prefer form over function. They build garbage inefficient houses that barely meet inadequate unenforced codes. Some of my biggest pet peeves with homebuilders include: 1) inadequate attic ventilation 2) NO roof overhang (this shades the sides of the house in the summer when the sun is nearly directly overhead) 3)they install sump pumps rather than design and install proper drainage (my parents owned an older home that sat very low - it never had a sump pump and the basement was bone dry for 25 years). The amount of energy that is wasted in North America (yes, Canada too - I have seen Holmes on Homes) due to these 3 simple things must be staggering. While I like the idea of putting plants on a roof (hey, I like plants!) I think more would be accomplished by addressing these 3 items in tandem.
It's not that simple. (It never is.) You did the right thing increasing your attic ventilation. You can improve this further by buying (or salvaging from your eco-store) white paint, and painting your shingles white. The best paint for this is one that uses TiO2 for pigment, as it radiates quite well in IR while reflecting in visible. Roof overhangs are a relatively cheap construction alternative -- until you factor in the land cost. When you are trying to get a zillion houses per acre, every bit makes a difference. While making larger lots and larger overhangs makes sense, it also means that there is more land converted from agriculture (or forest) to houses, and more waterlines, and more pavement. Sumppumpless (is that a word. Now it is...) houses in some cases are a matter of clever design, or landscaping. But if you insist on a basement in an area where there is a high water table, you've got a problem. More appropriate IMHO, is to build to the land. Live on a flood plain? Build on stilts. The bottom area becomes a place where the kids can play on a hot day. It's a place to park the car. Live on a wind blasted plain? Make a house that hunkers down to hide from the wind. Hot climate? Lots of mass, lots of insulation. Really big overhangs so that the sun doesn't reach inside. It's not rocket science. It's just not following the current trend because it's fashionable.
