2 Responses to “What is the role of renewable energy in addressing climate change?”

1. bestonnet_00 Says:
   May 12th, 2008 at 6:05 pm

   It is a political term to describe power sources that don’t emit much CO2 but which can’t actually provide the power our civilisation needs (so far no country has managed to get much more than 20% of their power from wind or solar and even then they had to rely on their neighbours’ hydro and nuclear as well as their own coal to prevent the grid from collapsing). Hydro is the main renewable energy source for electricity production right now but is opposed by most of the people who claim we need renewable energy (and unlike their opposition to nuclear power they actually have good reasons to oppose hydro).

   They are used mainly to delay the switch to nuclear power (which despite being not renewable should be good for millions of years at higher than current energy use) that would allow us to actually solve the global warming problem and thus contribute to global warming by keeping the fossil fuel industry in business.

   Basically the way it does that is that a bunch of windmills get built and start supplying power to the grid but because of natural variability in the wind they don’t provide that power all the time (20% of rated capacity is considered pretty good for wind) nor can we control when they provide their power so to use wind power you need a source of backup power that is reliable and usually that means fossil fuels (nuclear could be used but if you use nuclear for that then you may as well not bother with the windmills because the windmills would not reduce CO2 emissions or save money). Solar is less variable but PV cells cost a lot more and it still needs backup at night and partial backup on cloudy days. The need for backup means that the fossil fuel industry still gets to exist (and continue pumping CO2 into the atmosphere) if the way to address (if very badly) climate change is to use wind and solar.

   Hydro and geothermal have the reliability to be used for baseload although they only work in some locations and hydro power probably won’t be used where it can be because of the massive environmental damage building a dam causes.

   Wave and Tidal power when you calculate how much energy there is turn out to be way too diffuse to be useful. Biofuels show promise but not much because you need land to grow them on and that land could be better used growing food or even being turned back into forest.

2. Anders Says:
   May 15th, 2008 at 6:02 am

   Basically, the nonrenewable sources are fossil fuels and uranium. Fossil fuels are formed by, mainly, plants that have for millions of years absorbed CO2 from the atmosphere and then been deposited in sediments. As time goes by it forms in to oil, coal, and gas. When burning these fossil fuels the CO2 is released in to the atmosphere again, but at a much more rapid pace then what the biosphere can handle. It can’t absorb it all so the surplus adds to the atmospheric levels of greenhouse gases. They are then responsible for adding to the climate change we are seeing.

   Renewable sources include biomass, waveenergy, wind power, geothermal, and solar power. The advantage of using biomass instead of fossil fuels is that that CO2 is currently in circulation in the atmosphere and is not being reintroduced as the fossil fuels are. Wind, water, solar, geothermal are all capable of sustaing humankind with all the energy we ever need. We are also pretty close of having good means of extracting the energy from these sources. The main drawbacks are a restructure of our current infrastructure to replace the fossil fuels, and the fact they lack in durability. Fossil fuel, or nuclear power goes right on 24/7. But winds, solar, and wave energy don’t have that durability. There will be fluctuations (unless we can store the energy effectively) in the avaliable power. Geothermal is pretty good in this aspect though. (I, personally, would like to see an increaesed understanding for the Earth’s core and what a large scale extraction of heat would have on it, or, atleast, a scale to see the losses of heat throw natural processes compared to the extracted energy. This to ensure no negative consequences would come from this.) I think, once the problem of storing the energy is solved, that these sources will provide us with our need of energy.
   There are some possibilities around nuclear power, including breeder reactors, but I am not the right man to go in to that.

   *Greenhouse gases acts as an insulator, and, without it, the average temperature on Earth would be -18 degrees C instead of the +15 we see today. The solar radiation (short wavelength) is sent throw the atmosphere and reaches Earth. Some is reflected, particularly by ice, and bounces out in to space again. Some is absorbed and then reemitted with a longer wave length. These are also sent back in to space but the GHG’s can intercept these ones. They then reemit them in to all directions, and roughly 50% reaches Earth a second time. This is the greenhouse effect.

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