Im trying to find comprehensive info on total resource usage in both manufacturing and usage to work out what the trade off is for continuuing to use an existing CRT vs buying a new LCD panel same size. I know that LCD panels use roughly 1/3 of the power of a same size CRT but how long does it take to pay back the resource usage of manufacturing the new LCD if the choice is to replace an existing CRT?
I’m looking to take int account for water usage in manufacturing and all inputs, not just electricity and raw materials.
According to (my skimming of) that article a CRT uses 2283 MJ over its lifetime to function. The impact of producing an LCD is 2070 MJ and an LCD uses 853 MJ.
So you’d use more energy to produce and use an LCD than to continue using an existing CRT with a sunk production impact.
It says the energy to produce a CRT is 18,676 MJ and most of that is from glass production.
This is not a complete analysis. Since the CRT is not going to last forever, another monitor will need to be produced in any case. So it might be better to junk the CRT and start using an LCD. This will depend primarily on what discount rate you apply and how long the existing CRT will continue to be used. Let’s assume you switch to an LCD now or when the current CRT fails and no improvements in LCDs to make them even better savers.
Once the CRT fails you will switch to an LCD so the operating cost will be 853 MJ under either scenario and can be ignored. The extra cost of continuing to use the CRT is [(2283 - 853) * (whatever fraction of the CRT’s life is left)] discounted over the remaining life. The extra cost of switching to the LCD is moving up the 2070 production cost of the LCD (and presumably each later replacement LCD) by the time that the CRT would have lasted.
You can’t answer that question without knowing the discount rate. If the discount rate is extremely high then the immediate cost of 2070 will dominate and not switching is right. If the discount rate is zero then moving the production costs forward will not affect the total present value cost at all so and you don’t discount the ongoing saving so the present value of the savings is [(2283 - 853) * (whatever fraction of the CRT’s life is left)] and switching now is better.
thanks for above, can anyone find estimated lifespan for a CRT monitor vs LCD at same size? in my experience LCD’s last longer with decent quality while CRT’s lose contrast pretty rapidly… that’s my subjective feeling from still using 5-6 year old lcd’s and laptops but I’d like to have some figures to back that up.
Another issue is: Is the head generated by the CRT really a total loss? I used to use the heat from our monitors to suppliment the heating to our computer room/den. With the CRTs and halogen lights gone, I now will have to either get a small heater for that room, or increase the temperature of the whole house.
Well, that cuts both ways. Nearly 100% of the electrical energy consumed by a monitor of any description will end up as heat, visible light that escapes the room being the exception. If it’s a room that requires heating, the energy costs of the monitor will decrease the heating costs by roughly the same amount as an electric heater of the same wattage - though a heater will likely have a fan to distribute the heat it produces, while a monitor’s heat will tend to waft up to the ceiling and stay there.
If it’s a room that requires cooling, on the other hand, you pay more than double - the extra energy burned by the CRT, plus that much and more to run the AC to compensate…pesky Laws of Thermodynamics require that this cooling procedure can’t be perfectly efficient.
Not true. A modern air conditioner will provide several times more “cooling” than it consumes. If your CRT uses 200 W, you would be looking at 50-100 W of additional cooling expeditures, not 200+ W.
Still the point remains that the extra heat is only somewhat useful during heating season and even more costly in the cooling season.
Something many people forget is the cost of the additional desk space. This can be significant.
There’s also the issue of the weight. Not only with reference to lugging the thing around - large monitors require two people whereas even Mr Puniverse can lift even the largest LCD - but also to the loading on a desk. Try having 3 or 4 20" CRTs on a desk.
could you please clarify or support your statement somehow? Because this really goes against everything I used to know about the workings of heat engines.
It’s not apples to apples. New LCD screens are far more precise and clear in displaying text and provide a higher quality viewing experience. CRT vs panel as interchangeable display options is (IMO) a myth. New LCD panels are far, far better than CRTs for most PC viewing applications, even gaming as modern panels have excellent refresh rates and color saturation.
Air conditioners are heat pumps in reverse. The SEER rating of an air conditioner tells you the seasonal average of the number of Btus of cooling provided per watt-h of electricity. A 13 SEER unit would have a coefficient of performance of 3.43, which means for every W-h of energy it consumes it can move 3.43 W-h of heat out of the conditioned space.