BLUE, GREEN, BLACK – THE GREY AREAS OF ENERGY
Life is indeed colorful. We can feel in the pink one day with our bank balances comfortably in the black and the grass seemingly no greener on the other side of the fence. Then out of the blue, something tiresome happens that makes us see red, turn ashen white even purple with rage. Maybe controlling our varying emotions is just ‘color management’ by another name. Alex Morritt.
Blue energy is getting electricity from salt water – where rivers meet seas.
Two systems of water are separated by a semipermeable membrane. One system is really salty, the other is almost fresh. Fresh water would move through the membrane to the salty side and the salty side’s volume increases. This volume increase can be used to drive a turbine. This process is called ‘pressure retarded osmosis’. Another method takes the ions within the salty water and with special membranes produce electricity. This is ‘reverse electrodialysis’.
HOW MUCH OF THIS ENERGY IS AVAILABLE?
There’s a lot of energy of mixing at river/sea boundaries. Across the world about 37,000km3 of river water flow into the sea and the potential energy estimate is about 2TW. This can meet the energy demands of many nations.
However – as one might imagine – there is a lot of trouble getting this energy out. One trouble is that sea water and river water contain microorganisms that foul the surface of the membrane. If the membrane surface is covered with microbes, no water can permeate (flow) through it. Also, the membrane itself isn’t perfect. Instead of allowing only water to flow through, it sometimes allows salt as well. It is not perfectly semi-permeable. Sometimes, salt particles get stuck within the membrane support structure. When this happens, the water is not uniformly salty. Lack of uniformity in many scientific processes usually means trouble. This trouble is called concentration polarization.
A plant for ‘osmotic energy’ another name for blue energy opened in 2009 but closed down in 2014. Sadly, this plant could only produce enough energy to power a kettle.
People started thinking that if the salt water was really saltier then we might be able to get more energy. So, they’re looking at reverse osmosis brine – which is very salty waste water from desalination, dead sea water (because if that doesn’t work what else will, nothing is saltier than dead sea – except the first pot of rice I ever cooked). They’re also looking at ‘produced water’. Produced water is water that comes out with oil from an oil well. It might surprise many people to know that oil wells can produce more water than oil especially as they grow older. When an oil well is closed down (shut in), it doesn’t mean the oil in it is finished. It mostly means that the produced water is so much more than the oil and the oil prices are not high enough to take care of the water treatment costs.
Would this work?
Normally, it wouldn’t. But more regulation means more money spent in handling either reverse osmosis brine or produced water, so in a roundabout way it begins to look feasible. Regardless of this, it wouldn’t work everywhere. For this to work – we now see that we need really salty water. This could be in places where desalination is needed to make drinking water, or in areas around the dead sea.
ANOTHER KIND OF BLUE – BLUE HYDROGEN
Hydrogen isn’t blue. But depending on carbon footprint it can be green, blue, grey, turquoise or even pink. Lol. For something that is in reality colorless, it has done well for itself. Blue hydrogen is hydrogen from methane and in which the leftover carbon is captured. Methane is the main component of natural gas. Methane has one carbon atom and four hydrogen atoms. So, to produce blue hydrogen, I take one methane molecule, I break it down, I end up with 4 atoms of hydrogen and one atom of carbon. I capture than carbon and store it. Blue in this sense refers to carbon neutrality. I didn’t produce any carbon; I didn’t reduce the carbon in the atmosphere.
In actual fact green energy does not refer to a single type of energy source. The green color refers to the carbon negative nature of some energy sources. What does this mean?
Some energy sources are carbon positive – meaning they produce carbon oxides when they are used in processes. Some others are carbon neutral, they don’t take away from or add to the carbon already present in the atmosphere – like blue hydrogen. Some are carbon negative – they take away carbon already present in the atmosphere.
What’s the big deal about Green?
In the atmosphere – naturally, there’s 750 giga tonne per year (Gt/y) of carbon dioxide (CO2) but the activities of man have added 32Gt/y. So there’s no problem with the 750, but this extra 32 is what all this problem is about. Carbon capture has been able to sequester 0.04Gt/y and some industries take this carbon and use it to manufacture other things. They can only use 0.2Gt/y. Sadly what we have left is still a lot to deal with. But we still need energy. And we have become used to energy – zoom meetings, spa, warm food, PlayStation. Enter renewable energy.
Renewable energy is energy that is replaced faster than is being depleted. Hydrocarbons formed over millions of years that it is impossible for them to get replaced at the rate at which they have been used. Renewable energy is not so. The sun’s intensity may vary from time to time, but it is mostly there. Same as the wind or hydropower. However, these energy sources are not there all day long. This leads to a problem – the intermittent nature of renewable energy.
50 shades of Green
Its easy to think that all renewable energy sources are green. However, when you increase the timescale of some sources, the green fades into grey. What does this timescale thing mean? Imagine a solar panel installation in your home. As long as you use this solar installation, the electricity you use has no carbon released. Great.
Increase the scale to the time at the manufacture of the panel. The panels were not made with solar energy – they were most likely made with coal from China. Increase the scale a little farther to the components of the panel. They were produced with rare earth metals which are produced from mines. Increase the scale again and some of these metals come from coal mines.
Then we look at the plastics which are an important component of the panel – made from hydrocarbon. Where once the green was lush and blinding, as we look holistically at the process, the green dims – becoming pale green and sometimes grey.
There’s something bold about black. Something solid. Oil and Coal. The very foundation of life as we know it. The energy that has driven all great civilizations. It is actually hard to imagine life without hydrocarbons. There would be no Vanderbilt, no Rockerfeller, no Carnegie, no Ford, no Bill Gates. Some say this is not so bad. Perhaps. Perhaps not. But look around you – from your hair comb to your toothbrush, to the fertilizers, to your nail polish to car tires. Its hydrocarbon.
Perhaps it’s the bane of man – that light and darkness intertwines. That the food that nourishes our body erodes the organ due to wear. That sugar that sweetens the heart destroys the bowels. That the energy that lights up the planet darkens its skies and the very lifeforce of civilization threatens to end it. It’s the tree – knowledge of good and evil instead of the choice of life.
Black energy has brought us thus far – but nothing can stand in the way of an idea whose time has come. The earth has emptied her bowels to give us light. It’s time for the willpower and energy to renew.
SO MANY SHADES OF GREY
Think of energy as currency.