Technologies Enabling a Green Shift
The green shift is about transitioning from our current environment destroying economic system to a sustainable economic system where we use resources which are renewable rather than finite, and we do it in a way which does not destroy our environment.
To some this seems like an unsurmountable goal. Every month you can read about something you like doing which is bad for the environment.
Good vs Bad CO₂
However the problem is simply not as complicated as it seems. All problems with CO₂ emissions stems from one single source:
We utilize fossils in the form of coal, oil, natural gas and calcium carbonate. CO₂ which had been tucked away by plants and animals buried millions of years ago.
At some point the CO₂ stored in these fossils was part of the natural CO₂ cycle on earth. Then these animals and plants got buried. That led to a permanent reduction in CO₂ content in the atmosphere.
The goal is to avoid releasing this particular CO₂ back into the atmosphere. CO₂ from other sources such as burning of wood does not matter as long as we grow a new tree for every tree we burn. The growing of a tree will suck up all the CO₂ produced by burning a tree of similar size.
Calcium carbonate is from the shells of small fossilized shellfish. Concrete production release CO₂ bound in the calcium carbonate used in its production.
Thus we if we simply stop using fossil fuels and reduce our usage of calcium carbonate, then we will create a nice domino effect where suddenly almost everything we consume will suddenly no longer contribute to global warming.
This simplifies the problem to finding ways of substituting oil, coal, natural gas and calcium carbonate. So let us look at the key areas consuming these raw materials and look at alternatives.
Before going over the details it is important to realize that all biological life, as well as things derived from it such as oil and gas, as well as derivatives of oil and gas are fundamentally made from CO₂ and water (H₂O). The only differences are really just the specific ways we combine CO₂ and water. Gas, oil and plastic are really just chains of hydrocarbons (things made of carbon and hydrogen) of different length. Gasses are very short, different form of liquid oil have longer chains and plastic (polymers) have the longest chains.
That is why wood, plastic, rubber etc all can in principle be turned into the same gasses or oils. While oil and gas can be turned into different forms of plastic and rubber.
Charcoal which you make from heating up wood, is a substitute from fossil based coal. However we should not use more charcoal than necessary as that would consume a lot of wood. Wood or biomass can often be used directly as a replacement. Biomass is just a bag term for all sorts of biological material such as grass, wood, twigs, plant waste, saw dust, etc. You can fuel a coal power plant with biomass.
However a coal plant is just a way of generating electricity. You don’t need coal specifically to do that. Wind and solar could also be used to generate power.
Coal is used in iron and cement production as well. You could use charcoal for this, but smelting iron ore can also be done with hydrogen e.g. Thus you could use solar power to drive electrolysis of water, which produces hydrogen which can be used to reduce metal oxides, doing the same job as coal.
For cement production, coal is really just used for heating. You can use anything that allows you to heat. Concentrated solar could be used or electric heating.
Natural Gas Replacements
Natural gas is used for cooking, electricity production and plastic production. Cooking can be done with electricity, charcoal or ethanol.
There are a number of ways to produce renewable gas:
- Aerobic Digester. Basically you keep organic material in a big tank with microbes letting it rot with limited access to oxygen. This simulates what happens in the stomach of a cow. This will produce Methane (CH₄) and CO₂.
- Gasifier. Heat biomass with limited access to oxygen which produces syngas. Syngas is a mixture of Hydrogen (H₂) and Carbon-monoxide (CO).
- Pyrolysis means to heat the biomass without any access to oxygen. This will produce syngas and a sort of low quality oil. You need to process it further to be used as fuel.
All of these techniques can be combined with electrolysis of hydrogen. Electrolysis involved running an electric current through water containing salt, acid or base. This produces hydrogen gas (H₂) and oxygen gas (O₂).
We can use renewable energy from wind or solar cells to drive this electrolysis. The produced hydrogen can be combined with output from any of the methods of producing gas listed above. From the Aerobic digester we can combine the CO₂ with H₂ using the Sabatier reaction to produce methane (CH₄).
CO₂ + 4 H₂ → CH₄ + 2 H₂O
That means you can get pure methane from the first option rather than a mix of methane and CO₂. You can use sewage waste or plant waste from farms in an Aerobic Digester to accomplish this.
Instead of using electrolyzed hydrogen with CO₂ to produce methane we can use it with Syngas from a Gasifier to produce liquid hydrocarbons such as diesel through the Fischer–Tropsch process. Syngas contains CO and H₂ which can be used to create a wide variety of hydrocarbons.
(2n + 1) H₂ + n CO → CₙH₂ₙ₊₂ + n H₂O
The problem is that gasification does not necessarily create the correct proportions of carbon-monoxide and hydrogen that you need to make your desired fuel. You can use the electrolyzed hydrogen and add it as needed to get desired result.
Oil is used to produce many chemicals, plastic as well as for electricity production. However transportation is the main usage of oil. For instance in the US 70% of all oil consumed is used for transportation.
Thus oil replacement is thus a lot about finding other ways to do transportation, and in the cases where it cannot be done, find non-fossil ways of producing oil based fuels.
Battery electric vehicles (BEV) such as Teslas are demonstrating success with replacing fossil fuel cars with electric vehicles. The prices of batteries are dropping rapidly each year (2019), making BEVs competitive with gasoline cars within few years.
Since most oil goes to producing gasoline for personal vehicles, EVs would be able to reduce oil needs substantially.
There are of course other cases which are harder. Large long range commercial vehicles such as trucks and semi’s may not work well with batteries. Nikola, a company making semi-trucks is aiming to solve this with trucks with both batteries and hydrogen fuel cells.
For shorter distances such as for ferries, batteries and electric motors is feasible. For shipping which accounts for 7% of world oil consumption, other choices must be found. The Neoline project e.g. aims to create maritime transport propelled primarily by sails. Alternatively one can use synthetic fuels for propulsion, or a combination.
Battery powered air travel is already possible on short distances. Norway is already working on making its domestic airline network battery powered.
The challenge is long distance flight. One could imagine solving that by making multiple short hops, then replace batteries on each landing or switch planes.
But probably more realistic is the use of synthetic fuels. We’ll cover synthetic fuels in a separate section as it is useful for trucks, ships, air travel and electricity production.
Plastic and Rubber
We can get natural rubber from rubber trees and this is where most of the rubber in car tires come from. It is also possible to recycle it, so we don’t oil to make rubber.
One can get bioplastics directly from feedstock such as vegetable oils, starch, sawdust, food waste etc. However they cannot substitute all types of plastic yet.
However as discussed earlier there are ways of creating synthetic fuels and biogas which could be further processed to “normal” plastics. Usually this is a question of costs. Adding more steps will of course increase costs.
Synthetic Fuel Production
There are lots of way of producing synthetic fuels, best known are probably biofuels.
These involve growing different forms of plants which are converted to fuel. Cooking oil, soybean oil and animal fats for instance can be used to produce Biodiesel.
An alternative which is used frequently in Brazil is ethanol. This can be produced from sugar cane. Brazilian sugar cane is about 3–4x as efficient to use for ethanol production as say American corn. This matters as using too much land area for fuel production would start to negatively affect food production.
However even sugar cane takes a lot of farmland. What has been considered the next stage in biofuel production is to use algae fuel. Algae bioreactors give 10–100 times the yield of regular crops when used for biofuel. That saves previous farmland. The tradeoff is that the unit cost is higher. This is always the tradeoff in all food production. Traditionally using animals required less effort for humans to obtain 1 kcal or energy. However they require much more space.
An alternative to algae is to use cyanobacteria producing sugar in a bioreactor. These give up to 700% higher yield that algae. However they are used to produce sugar rather than oils. Sugar is an excellent feedstock for producing ethanol which is well understood. Collecting sugar is easier than collecting oil from the bioreactors.
The alternative to biofuels which relies on growing biological things is to use electricity to produce synthetic fuels. This goes under a number of different names such as:
- Power-to-gas, which typically refers to using electricity to produce hydrogen, which is either used directly or combined with CO₂ to produce methane. Some kind of gas fuel in other words.
- Power-to-liquid, refers to using electricity to produce a liquid fuel. This will also typically have an intermediate step of hydrogen production from electrolysis. Nordic Blue Crude is an example of a company making synthetic oil called blue crude. Like fossil based oil it can be refined to any kind of petroleum product.
Electrofuels and biofuels can be used either for vehicle transport, plastic production (if not taking the bioplastic route) or for power generation. Electrofuels probably has the biggest potential as photosynthesis is quite inefficient compared to solar cells. Hence an area covered with solar cells can be used to produce far more electrofuel than the same area can produce of biofuels.
Calcium Carbonate Replacement
Calcium carbonate is sort of renewable as it is constantly being created by dead sea animals. The point is to see if we can reduce the usage of it.
It is not primarily Calcium Carbonate usage which makes concrete production emit so much CO₂, but rather the common usage of fossil fuels for heating. As pointed out earlier we could use other ways of doing that, either electric heating, charcoal or biomass.
An alternative to that is to cut down the usage of concrete to only the places where alternatives are hard to find. In most cases stones, bricks and wood are great alternatives.
Wood is perhaps the best choice by far. In most of the northern hemisphere there is a net growth of forest, thus we can use a lot more wood without depleting our forests. The beauty of wood is that it is essentially a CO₂ storage. Every time you build a wooden house, your have taken a lot of CO₂ out of the atmosphere, which will not return until the house burns down or rots. Thus if we could build more of our cities in wood, we would bind a lot more CO₂.
Over the last years we have been able to engineer wood in numerous ways to give it new properties. A recent example is how some researchers made wood which is stronger than titanium alloy, while lighter and cheaper.
It is claimed modern engineered wood is so good that it can be used to build wooden high rise buildings. Perhaps it seems scary from a fire perspective, but apparently solid wood does not burn that well, and apparently keeps its strength better during fire than steel. Japanese castles were famously made of wood but quite resistant to fire arrows, because they were covered by fire proof lacquer or plaster.
Electricity Production and Storage
Underlying almost all of the solutions outlined above is the need for cheap renewable energy. Electrolysis of water to produce hydrogen require a lot of power. If that power is expensive so will the hydrogen be as well, consequently the synthetic fuel, gas, plastic or any other derived product would get expensive.
However renewable energy has an amazing property:
The marginal cost of producing an extra kWh from already installed wind turbines and solar panels is ZERO!
This is fundamentally different from power generated from coal, gas or oil. Every kWh generated from a coal plant requires you to spend money buying coal. The cost of wind and solar power is primarily the cost of construction. If the sun shines really well one day, the extra power produced does not cost you any extra money.
This has the effect that whenever conditions for wind and sun is so good that excess power is produced, the price of the power will become very low. It may even get negative. That means in these periods hydrogen can be produced from electrolysis almost for free. Cheap hydrogen means we can produce electrofuels cheaply.
This will increasingly become the case as renewable energy starts to make up a larger portion of the energy mix.
Invariably when discussing renewable energy, people will ask:
But what do you do when the sun doesn’t shine or the wind doesn’t blow?
We have already partly answered this in our discussion of electro-fuels also often referred to as Power-to-X, a sort of bag term to encompass Power-to-Gas and Power-to-Liquid. Power-to-Gas for instance gives us a way of fueling gas power plants, which could operate when the sun does not shine.
However the problems requires a more detailed analysis.
Long Term vs Short Term Energy Storage
There will likely not be one single ultimate storage solution, because there are a variety of storage challenges to meet.
One problem is the day cycle. The sun shines in the day but not at night. Thus we need a way of storing energy generated in the day to be used in the evening. This will be short term storage, just for a few hours.
In this case batteries are a good solution, because they are very efficient. You get most of the power you put into them back. Since the batteries are filled and emptied very frequently (every day), it would have been costly over time to have an inefficient storage where energy was lost every time.
We can thus afford to spend a lot more for this kind of storage. Expensive but efficient storage works well when it is being utilized frequently.
However we also need long term storage. The sun may shine a lot in the summer and we get a lot of power in the summer. However the power generation from solar will drastically fall in the winter. Thus we need to be able to store energy in the summer to be used several months later.
In this case batteries are not the best solution as battery storage is expensive. For long term storage, storage price is more important than efficiency.
In this case solutions such as Power-to-Gas becomes more viable. It is far less efficient, but storing gas in a large tank, isn’t very expensive. Alternatively one can generate ethanol, methanol or other simple fuels which can be synthesized from hydrogen and a good source of CO₂. Both very easy and cheap to store.
But the considerations of what solution to pick can get more involved. Let’s look at the strategies somebody who is in the business of buying cheap power for storage and selling it when the price is high.
Technologies and Strategies of an Energy Storage Business
Let us consider companies competing with each other to buy cheap electricity, store it and sell it later when the price is higher.
Say each company get a X million dollars each to buy a storage solution. You got spend that money to buy a small storage with high efficiency or a bigger storage with lower efficiency. What should you do?
If the power is very cheap to buy and you can sell it for a high price, then wasting a lot of power when you store it isn’t important because you pay so little for it. What matters is that you can store a lot of it, and sell it for a lot later.
However if the power is quite expensive to buy, you want efficient storage. Otherwise you have high capital costs while storing it. What do I mean by that? Money isn’t free. You typically get more money by borrowing it. The more money you borrow, the more you pay in interest. Buying very expensive power requires more money, which means you get more to pay in interest. You don’t want power you paid a lot of money for get lost. Hence you want efficient storage in this case.
That is one aspect, another one is economies of scale. Some storage solutions scale down very easily. The unit price of a battery does not increase that much by putting in a house compared to filling a whole warehouse with batteries.
Other storage solutions get really cheap as you scale them up.
As you can imagine there are is a wide variety of storage solutions which offer different tradeoffs in cost, efficiency and economies of scale. Lets look at some choices:
Even within batteries there are different technologies with different tradeoffs Lithium-ion which dominates today, scaled down very well. You can put it in a cellphone or a car. They are efficient, but relatively costly.
Flow batteries such as Vanadium, have less efficiency and don’t scale down as well as Lithium-ion, thus you may not want to use them in your house. The fixed cost or minimum cost to setup the system is higher. However as you make them bigger you get economics of scale and the unit price drops. Flow batteries are a bit like a fuel cell system.
An analogy would be a hydrogen fuel cell combined with an electrolyzer. When you use power hydrogen and oxygen is consumed to produce water. Charging is the same as running the electrolyzer to produce hydrogen and oxygen again. Such a system obviously does not scale down well because you need tanks, values, pumps etc to have the whole system running. However when you make it bigger it gets cheap, because it is not expensive to simply make the tanks bigger.
Thermal Energy Storage
There are various solutions to this. Best known is probably molten-salt which can store a lot of thermal energy. These solutions compete with batteries on storage time, they usually for storing energy in 4–6 hours.
Efficiency is good, but these need to be large to be economical.
Compressed Air Energy Storage
Compressed air storage can compete with batteries but have quite different advantages and disadvantages.
- Efficiency is just 40–52% compared to 70–90% for batteries.
- High durability. Lasts much longer than batteries.
- Low energy usage in production relative to storage. Batteries requires more energy to make, so compressed air takes shorter time to pay for itself, in terms of energy usage.
Compressed air does not scale down as well as batteries. Needing things like compressors, a minimum system is obviously more expensive than a single battery. However systems can be made small enough to fit in a house. In a house you can increase energy efficiency by utilizing heat produced from compression to heat water for cooking, washing, etc. Cooling produced when the power is produced from the system can be used for refrigeration, air conditioning, etc. This will push up efficiency numbers.
Compressed air can be scaled up to grid size and get quite cheap. However this will require access to caverns or other large places which can offer cheap large scale storage.
This is basically utilizing a hydro-electric power station to store energy. When you have excess energy you pump up water into the reservoir. Then you can release it to generate electricity later when needed.
While this is an efficient and relatively cheap solution at scale, the problem is that most areas of the world don’t have the terrain to support pumped hydro. Companies like Quidnet Energy solves this by pumping water into deep reservoirs underground.
You may have seen oil shooting up from an oil well before. It comes up at enormous pressure. That is because the reservoir is deep underground and the earth above is pushing down on it creating strong pressure. The deeper you store it, the higher the pressure will be. Thus you could e.g. pump water into abandoned oil reservoirs. Whenever you need power you open the value and let the water shooting up drive a turbine.
This approach should be cheap at scale. You don’t really pay for the size of the reservoir you store in. If leakage isn’t a problem this should allow long term storage.
Matching Supply and Demand of Power
On of the reasons why need to invest in energy storage is because wind and solar power generation varies. Thus we have both variable supply and demand. Or do we?
For a long time it has been assume that there is little to nothing you can do about regulating demand.
But there are actually companies that have come up with an ingenious solution to adjust demand. They install equipment on various industrial machines in a multitude of factories.
The owners of the factories can then toggle on as they see fit the ability for these demand regulation companies to turn off their industrial machine.
At certain points you cannot stop a machine. But it turns out that there are many machines in a factory which don’t need to run continuously.
The Grid can electronically pick up that power production is dropping and then send out a request for demand reduction. This will cause all factory machines which have been put in the pool of machines available to be turned off to be turned off. Or rather the number of machines needed will be turned off until demand for power matches supply of power.
This can be done at almost any level. Some companies also do this for consumers. Basically you get pinged by the company to reduce power consumption. They will then pay you based on how good you are at reducing power usage. It may mean that you turn off your dish washer or vacuum cleaning at that point. This can be automated. E.g. they can have a controller setup on your fridge to turn your cooling off temporarily. Turning the fridge off for up to an hour has little impact on the freshness of your food.