Welcome to the Cquestrate blog
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Energy independence
So you want to produce all the fuel you need without importing it in from other countries, with all the messy politics that that can involve. Here’s how:
Use the carbon dioxide generated from the first step of Cquestrate’s process to allow you to grow algae (the availability of carbon dioxide is the rate limiting constraint if you have even a moderate amount of sunlight). Vent off any oxygen generated from photosynthesis and then decompose the algae in anoxic conditions (no oxygen) - this will generate methane. With solar irradiation at 20MJ per m2 per day and an efficiency of converting sunlight to chemical energy of 1%, you are able to generate 730GJ per ha per year. Wholesale prices for methane are ~USD10 per GJ, so you have a per hectare yield of ~USD7,300. Farmers would be delighted with that kind of yield.
Now, it isn’t quite that simple - there are high capital and operational costs involved in growing algae - but there are reasons to believe that producing methane will be far cheaper than producing biodiesel (although biodiesel sells for more). For a start, if you want to produce biodiesel you have to get it out of the algae cells, by breaking down the cell walls and using solvents, which involves energy and expense. Methane by contrast is a gas, which will separate out without the need for any expensive processing.
Another benefit is that algae don’t by choice produce much of the lipids that you need to produce biodiesel. You have to stress the algae, by making the conditions in which they grow abnormal. Photoynthesis yields sugars - the algae then have to go through a series of biochemical steps to convert those sugars into lipids - and each step reduces the overall energy efficiency conversion from sunlight to chemical energy. By contrast, to produce methane all you need to do is to allow the algae to do what they do most naturally - produce sugars - and then allow them to decompose (this is helped by two sets of organisms - the first set breaks sugars down into acetic acid and the second set breaks acetic acid down into methane and carbon dioxide). The energy efficiency of this decomposition process is, in theory 95%, but in practice is closer to 80%.
Current projects which seek to produce biodiesel from algae use the flue gases from power stations as they are a concentrated source of carbon dioxide. This means that the algae needs to be grown near the power station and that tends to mean high land prices. Cquestrate’s process can be performed on cheap land far away from a power station as its source of carbon dioxide is from the calcination of limestone.
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Making the deserts bloom
The first step of the process - heating limestone up until it breaks down and produces lime also generates carbon dioxide. This can be used to help grow algae - either for food or for biofuels. It also allows the growth of biomass in very dry environments. How so? Think of it this way:
Say you wanted to grow a crop in an arid environment - you haven’t got much water, so you seal your water and the crop that you are growing inside a greenhouse. Sealing it up stops the water evaporating away, but as the plants grow they use up all the carbon dioxide in the greenhouse. So you decide to put some fresh air into the greenhouse, but when you do this you have to remove the old air, and when the old air leaves you lose all the moisture … back to square one - it doesn’t work.
If, however, you have a sealed tank of water and into it you introduce pure carbon dioxide, you are in a much better position. The tank has a transparent lid, so you have sunlight; the water in the tank contains algae - you have everything you need for photosynthesis. Because the tank is sealed you will not lose water by evaporation. (You will need to vent off a small amount of oxygen generated by the photosynthesis, but you will only lose a small amount of moisture because of this).
Some fairly simple chemistry shows that for every kg of sugars that you produce, you need to use 600g of water. Undoubtably, you will lose some more water in the practical application of the process, but the water usage will be less than 10kgs of water for every kg of sugar produced. This sounds like a lot, until you realise that growing crops in really dry places like Egypt requires 1000 kgs of water for every kg of crop produced.
Or to put it another way, it is possible to grow crops with 1% of current water usage. So, paradoxically, the way to make the deserts bloom is to heat the right kind of rocks up.
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