Section Three - Our Energy Future is Crap
Not as dire as it sounds. What follows is still on the theme of water usage. I am going to sketch out a basic design for the sewage treatment plant of the mid twenty-first centaury. A place of wonder that makes money for the government meaning services can be supplied for less and lowering taxes. How do we accomplish this wonderful event? Feces, a great energy resource we now largely view as waste.
How it Works
Let us begin with our toilet where we flush waste that at present, in most municipalities, is treated then dumped into the environment taking energy and money out of the system as a whole.
From the toilet, which should be flushed with rain water, see section one - rain catchment, the waste will flow to the treatment plant as it does today. Here the solids and liquids will undergo a separation process, basically straining the waste. Let's follow the solids that at this point are a sticky semi liquid sludge. This sludge is directed into fermentation tanks where it is allowed to rot generating methane gas, as it would anyway. This gas is collected and used to fuel methane powered electric generators. This electricity is sold to the electricity grid supplying a source of revenue to the community. The waste heat from the generators is shunted into the fermentation tanks maintaining them at the optimal temperature for methane production. Additional waste heat can be used for supplying hot water and heat for the treatment plant in general. This is done through a simple radiator and pipe system not unlike the one in most of our cars.
The advantages to this are enormous. For one, methane is about six times more effective as a greenhouse gas then carbon dioxide. By converting the methane into carbon dioxide through burning you immediately reduce the climate impact of the city's solid waste to one sixth of what it would otherwise be. The electricity and heat are also bonuses adding money to the city's coffers and reducing heating costs.
The system so far, I am proud to say, has been adopted by my home town, Hamilton Ontario, Canada. I will give credit where credit is due and I must salute my city council for having the vision to do the right thing on this score. If any of you are reading this, don't get use to it. I'm still an annoying git who thinks you could do better!
I am aware of another city in the states where they use a similar system to supply the fuel that they run their city vehicles on. The basic system dates back to the late eighteen hundreds when it was used to supply methane for gas lighting for several English cities.
The waste products from the solid processing are a sludge that can be dried using the sun and carbon dioxide. We will come back to both of these later.
For now let us address the separated liquid waste. This should be channelled into algae farms. These are basically shallow ponds with a low, greenhouse-like cover. The waste water is already full of nutrients that the algae will absorb to grow thereby cleaning the water.
The waste carbon dioxide from the electrical generators is channelled into the algae farms. This makes use of the heat being lost in the exhaust by warming the farms and the carbon dioxide is fixed by the algae, keeping most of it out of the environment. A heat dissipation system, a radiator, can be used to pre-process the exhaust during periods of high heat and bypassed to heat the algae ponds during periods of low heat. The exhaust gasses should be bubbled through the pond water, which will have the effect of catching most forms of pollutants that might creep in, though these would be minor at most.
The algae is allowed to grow. Now what happens next depends on future science. Currently, Exxon is funding research to bio-engineer algae that could produce more and better oils. These bio-engendered forms would presumably excrete the oil and it could be collected and separated from the water. The oils would then be processed at existing petroleum processing plants to make petroleum products.
At present what would be done is the algae would be harvested and processed to make bio-diesel. There is a pilot plant in the USA that is currently developing the techniques to do this on an industrial scale. The bio-diesel is an ideal home-heating fuel and can be used to run any diesel engine. Its one draw back is a tendency to become a gel at temperatures around 10 degrees C / 50 degrees F or lower. There are regions where this isn't a problem and regions where it's not a problem during the summer. Also, nothing says you can't cut diesel from other sources with bio-diesel to make a more temperature-tolerant, hybrid fuel. Another use would be to use the bio-diesel to run a diesel-powered, electric generator, taking the waste heat from that and using it to keep the fuel in the storage takes liquid while feeding the carbon emissions back into the algae farm and the electricity into the power grid.
After being processed for its oils, the algae can be mixed with water that has done its time in the algae tanks and fermented to generate ethanol. That ethanol can be distilled using waste heat from the electrical generators and used as an additive to gasoline doing the job of several of the most polluting additives currently used. This cuts total fossil fuel consumption without wasting food crops and arable land that could better be used to feed people.
The water put in the algae farms will undergo a process of settling and bio-purification as the algae pulls the toxins that are its food out of the water. Much of the water will evaporate during several of the processing stages, off gassing to rejoin the hydration cycle. The water that remains at the end will be almost pure and quite suitable for uses such as irrigation. Another use, if the water isn't completely pure, would be the creation of artificial wetlands that will provide wildlife habitat and natural water purification as well as drawing carbon out of the atmosphere.
What remains of the algae after fermentation can be dried and mixed with the post process sludge left over from the treated solids. This material is a rich soil that can be used for the growth of non-edible crops such as hemp, cotton, pulp trees and soy, if used for ink production. Sadly, due to the fact it may contain heavy metals, that would be dumped into the environment by most treatment plants anyways, it isn't advisable to use this sludge for food crops. Although the areas the sludge are used on will drop heavy metal concentration over time due to natural processes.
Now you may say this sounds like perpetual motion, but if you think about it there are several energy inputs. First the waste material. Feces is loaded with potential energy. All this process does is transform it into a form we can use. Second the sun on the algae inputs energy.
It is interesting to note that several aid organisations have been supplying small methane composting systems to homes and villages in the third world. This is done in an attempt to supply amenities such as electricity that will encourage people to stay in rural areas and not add to the over crowding of the cities. Another benefit of this form of grass roots methane composting is it can preserve trees by reducing people's reliance on wood for heating and cooking fuel.
So there you have it. A rich energy source that most of us are currently flushing away.
Questions
Now for some reasonable comments people have made to me.
Question. If it is cost effective why isn't everyone doing it?
Answer. Because we haven't placed any real costs on environmental degradation and up until now there were relatively plentiful sources of non-sustainable energy.
Question. It can't supply all the power the city needs.
Answer. No it can't, but think of it like your kid earning money with a summer job for collage. If he or she earned let's say 20% of what it costs that can make the difference between them getting an education and them not, even though you're paying the other 80%. That 80% might be all you can afford. Even if you can afford more the child's contribution will free up money for your retirement savings. We need to shift to an energy mosaic with many small sustainable inputs taking the place of large unsustainable ones. Also it makes a profit. The city in the USA I mentioned earlier found that if they factored in the fuel costs for running the city vehicles, in other words looked at how much they would have had to pay for fuel, the sewage treatment plant was running at a profit. I don't have the numbers for the Hamilton facility, but I'm sure they're similar.
Objections
Objector. Those algae pools will leak carbon dioxide.
Answer. Yup, some will escape. Would you rather be kicked in the head one time or ten? Same question.
Objector. Disease organisms will be in the methane.
Answer. Which is burnt to generate electricity. This is a legitimate objection if one is using the methane for cooking fuel, but not for this application.
Objector. Those algae farms will take up a lot of space.
Answer. Some I admit, but they can be put on roof tops where the water evaporation during the summer will help cool the buildings and on waste land left from demolitions. There is also land poisoned by industrial waste, old land fills. Heck they could even be incorporated into floating barges. Let's face it, we've created quite a mess for ourselves.
Summary
In short, we've largely ignored a major resource for too long. This won't solve all our problems but it can alleviate them reducing our reliance on non-local energy and drastically reducing a major source of greenhouse gasses.
Section Four - Hot Water Pre-heaters
