SOLUTIONS (Part 3)
COMMERCIAL APPLICATIONS. COMBINED HEAT AND POWER
This process, Combined heat and Power (CHP) is not something new. As I mentioned in the last post, it was introduced in the 1880’s in Manhattan, and is in fairly widespread, if not unheralded, use throughout the State of New York. When grid power started to come on line, it faded a little into the background, but was still in use by those buildings where it has been used regularly and on quite a widespread basis to this day. In the early days, and as is the case now with some places still using the process, coal was the main source of fuel for this form of generating power. Again, the coal was burned to generate steam to drive a turbine which in turn drives the generator.
However in this day and age, different fuels are being used. Nearly all the derivatives of oil are being used, from the gas fuels through to the liquid fuels and even to the petroleum coke as well as other fuels, Biomass, bio diesel, as well as ethanols and methanols.
The drive mechanisms have also evolved through the ages, and now the efficiency of those plants has increased markedly, and the size has shrunk considerably as the technology becomes better. some units have an efficiency approaching 95%.
Just how one of these modern processes works is like this, and I’ll use one powered by natural gas. Again, you say, this is still a fossil fuel, but unlike coal, the CO2 emission component is considerably smaller than it is for an equivalent coal fired plant of the same size. The gas drives a turbine and the turbine drives a generator. The hot exhaust from the turbine, instead of being exhausted into the surrounding environment, is collected and used in a secondary manner. It is used to supply heating for the building in the cooler months, and is also used to drive reverse cycle airconditioning to cool the building in those warmer months. So, effectively, the original fuel is being used in three ways, hence the name for this process, Trigeneration. Where it is used for the generation of power and heating alone it is called Cogeneration.
I mentioned the number of sites actually using this process amounts to 384 in total. Most of these are using Natural Gas, and most of those are buildings with a reciprocating engine as the power plant. The ones producing the largest amount of power are using the most efficient combined cycle turbine as the power plant with Natural Gas for the fuel.
The large one in Manhattan that everyone would be most aware of uses a boiler to produce steam and is powered by Natural Gas also. It produces 500MW and is operated by ConEd.
All up, this process is used by schools, hospitals, nursing homes, apartment buildings, and private companies.
It produces nearly 6,000MW of power, which is the equivalent of three large baseload power plants.
The beauty of working with smaller units like this is that they can be run on a continuous basis.
This large database shows those facilities in New York where the process is being used.
This may just be a solution that is worth following. The joy here is that buildings can actually be retro fitted with the system. The individual cost for a high rise building might be in the vicinity of $1.5 to $2 Million, but that will give you a quite adequate 3 to 4MW sized plant that would supply all the power for that larger sized structure. Something like this would take time to implement on a large scale, but if things were to actually become desperate, then buildings could be fitted with this system, and as the numbers of buildings rose, then baseload coal fired plants could be decommissioned.
|CIS Tower Manchester England.
Image from CIS. Click on image for a larger view in a new window.
A second option could also be what is called BIPV, an acronym for Building Integrated Photo Voltaic, which is the use of solar power glass panels as the outside of the building. This would not provide enough power to totally supply the whole building, but it could augment the system providing extra power during daylight hours when most of those tall office buildings are occupied with their work force.
There are quite a few buildings that actually use such a system already, and one of the most startling examples is the large CIS building in Manchester in the UK. This building was actually retro fitted with the solar glass panels on the front of the building, the blue glass you can see on the facade there. There are around 7200 panels on the building of which just under 5000 are active. Each panel generates 80 Watts of power but that would be under full Sun. The total power could be conjectured at just under 400KW, but due to the variability of solar power, then that is not a constant maximum output. There is also conjecture that the original outlay of five and a half million pounds Sterling will never be recovered in the life of the solar power production from the panels, but this is an example of just how something like this can be achieved, can look good, and actually serve a purpose.
This would be a huge cost to retro fit buildings with this installation of BIPV solar glass to augment the CHP, but it could be a factor that could be taken into account in the architecture phase of new buildings that are scheduled for construction.
There is an excellent short video that I’m going to include here with this post regarding the use of CHP.
It was done as part of an excellent Science program on the Australian ABC. The program is called ‘Catalyst’. The ABC has rights to the broadcast so I feel it would be unfair of me to link the video straight to this page, so as part of your interest, I’m going to set you the task of navigating to the video, and actually taking the time to watch it, because it is worthwhile to do so. After taking this link to the Catalyst website for the program, you’ll see a small image with some introductory text below that. At the bottom of this short text, you’ll see an icon of a video camera with the time alongside it and then a choice of two methods of viewing the short video, either Windows Media Player or Real player, and your computer should have one or the other. Click on whichever you have and watch the video. It’s an investment of 11 minutes of your time but it it shows something that just might become a viable option for supplying power in those large cities.
It is in these large cities where huge levels of baseload power are required. When a breakdown of actual power consumption is viewed, it might seem surprising that consumption by the residential sector only amounts to just on 38% of the total power consumption for the entire US.
So, the vast bulk of generated electrical power is consumed in the Commercial and in the Industrial sectors, and the vast bulk of that would be in those larger cities. This is where CHP is being used currently, in those two sectors, and by extrapolation, in those larger cities. However, the total CHP usage amounts to only 7% of that total Commercial and Industrial usage of electrical power. Currently CHP generates an amount of power equivalent to the output of 20 of those large baseload power plants.
If the Kyoto Protocol demands we decrease the emission of greenhouse gases to a level 5 % less than what was being emitted in 1990, we have already worked out that would mean the decommissioning of 50 of those large coal fired baseload power plants.
Would it not stand to reason that with the conversion of some of those workplaces in the Commercial and Industrial sectors to using CHP, something like this might actually be able to be accomplished. It would be a costly exercise and would take time, but it is actually something that can be done. The technology has improved markedly over the years, so this option is more attractive than it might actually seem. It would take a strong will on the part of Government, and the willingness of Commercial and Industrial enterprises to take this stand and make the move. As is indicated in the short video, this CHP is in widespread usage in a fairly large English city, and the cost of the electricity produced is equivalent to what is being charged by the Electric Authorities. The initial outlay can be recouped within a relatively short period, and after that the actual savings would be quite large because electrical power costs would no longer impact upon the bottom line.
In this manner, the residential sector could tinker at the edges with the vastly more expensive option of constructing plants using renewable sources of questionable capacity for the dollars spent.
Again, I urge you to take the link and watch the video.