The carbon cycle
September 26, 2017 by Denis Pombriant
Every living thing is dependent upon green plants for sustenance. Whether you’re a vegetarian, a herbivore, or a carnivore if you look back far enough in your food chain, what you eat comes from plants. Even fungi that breakdown once living things in the process of decay, earn a living from green plants. Without them life as we know it is impossible because only green plants can capture solar energy and make it available to living things.
Plants participate in the carbon cycle a huge and ongoing process that captures energy and carbon turning it into food for animal life, and that eventually returns the carbon to the air thus renewing the cycle. The carbon cycle also has interesting side cycles too and the best-known one involves fossil fuels.
As the name implies, fossil fuels are made of things that were once living but through a quirk of nature those living things were preserved first in sediments and later, underground, for many millions of years. Geology turned dead things into the coal, petroleum, and natural gas that we use today. But these fossils are only available in limited amounts and we’ve been using them for over 150 years already; moreover, energy demand grows at about 2 percent per year. And since it takes millions of years to produce fossil fuels they are irreplaceable.
The human race’s energy appetite grows not simply because population grows. We also find new ways to use energy. Moreover a good deal of fossil fuel never gets burned but is used as the raw material for all kinds of products from the rubber in a tire to plastics, synthetic fibers, and even pharmaceuticals.
There’s ample evidence that the supply of fossil fuels is not keeping up with demand. Large discoveries from decades ago supply our needs today but our exploration efforts have not kept up with growing demand for many years. So it’s reasonable to ask about a plan B.
There’s a robust community of people dedicated to developing energy sources that are not associated with fossil fuels. Their solutions such as solar and wind, contribute almost nothing to the pollution problem and generate clean electricity. Generating clean electricity is not limited to the solar and wind farms we see springing up. It also includes geothermal power and space based solar generation (SBSP). In subsequent postings we’ll look at each option individually.
We’ll also look at some of the challenges of replacing fossil fuels as the primary energy source. Generating and using electricity will require a somewhat different electricity grid; one that’s more resilient to attack or failure. It will also cause fossil fuel industries to contract. We’re already seeing contraction in the coal industry as natural gas outcompetes coal on price and pollution. The fossil fuel industry has literally trillions of dollars invested in its infrastructure from oil fields and wells to pipelines, tankers, and refineries. Over time their capacities will become surplus, no longer needed. It will take concerted public-private action to ensure that converting from fossil fuels to clean electricity does not precipitate an economic crisis.
At some point in the near future, we can expect that electricity generated from solar, wind, and other sources to achieve grid parity meaning it will be price competitive with power generated by burning fuels. As this process continues look for a trend of retiring power plants as older and dirtier generating stations are taken off line.
Supply and demand
What happens when the supply of any product continues to dwindle is predictable. First prices rise because of simple supply and demand economics. If demand is not that elastic as is the case for energy, consumers will have to find ways to pay the price. Even when supplies dwindle and costs rise, people still need to get to work and conduct their transportation centric lives. They still need to heat their homes in winter and they need electricity year round. So almost regardless of cost, demand for energy will remain high.
Substitution comes next. When a commodity becomes expensive markets seek alternatives or substitutes. For instance, if steak becomes expensive, people might buy chicken as a lower cost substitute. Eating chicken instead of steak is relatively simple. People can use the same utensils to cook it, they digest either one easily enough, and the supply at a supermarket is usually adequate for either product.
Substituting energy is in some ways like that but in other ways it is not. Our electric appliances don’t know or care how electricity is generated but our cars, trucks and especially aircraft do. We can build electric vehicles but we can’t easily convert fuel burning vehicles to electricity so there’s a costly barrier to conversion. When electricity becomes abundant and cheap enough we can expect to find more people purchasing electric vehicles but for a long time we can also expect that there will be a mix of cars and trucks on the road.
The situation is a bit different for air travel. Electric powered drones are coming to market to deliver packages and some people have already flown electric aircraft for short distances. But so far there isn’t a substitute for fossil fuel driven jet travel across an ocean or a continent and there might not be. Even if we could imagine electric aircraft with large batteries, as long as those aircraft rely on propellers they won’t be a match for a jet. Two things flow from this observation.
First, if we want to preserve our ability to fly fast and cheap, we should begin preserving our fuel so other forms of transport that can more easily swap to electricity should do so.
Second, other forms of travel like high-speed rail, can take up some of the slack but it will require a reordering of our society to get the full benefits.
Jet airliners routinely fly above 30,000 feet at speeds around 500 mph making a coast-to-coast flight about 6 hours long. In contrast, high-speed rail is defined as a train capable of traveling on special tract at minimum speeds of 124 mph and maximum speeds of 155 mph. That’s a far cry from jet travel and it turns a 6 hour trip into a day-long affair.
If jet fuel gets expensive, as it will if petroleum supplies are threatened, high speed rail will look increasingly appealing but with a caveat. At some point market forces might come to bear building up the middle of the country so that centers of excellence in manufacturing, banking, entertainment, culture, technology and more, are located equidistant from the population centers of the coasts. Of course this is a long-term situation and alternative technologies such as the Internet, virtual reality, and others not invented yet, may have a dampening effect on travel demand. But high-speed rail will be a useful substitute if society needs to further ration jet fuel for trans oceanic travel.
Transportation fuel should be the lowest priority for the remaining fossil fuels, especially petroleum. Rather than bit in cars, it should be conserved for air travel and for raw material needs of the synthetic materials industries such as plastics. Such a drastic reduction in the use of fossil fuels will do a lot to reduce pollution. At the same time electric transportation modes can be put into service so that the impact on consumers is minimal. But the changeover will take time during which pollution continues to accumulate and fossil fuel supplies dwindle.
How much fossil fuel is left?
When you consider the need for an adequate supply of CO2 for food production and the need to keep it out of the air, the inescapable conclusion is that some of amount of carbon should be warehoused in organic matter, which could satisfy both conditions. If we can grow more green plants they can capture more carbon keeping it out of the air; if those plants happen to produce food for human consumption, so much the better. Of course carbon I this way will not stay out of the atmosphere for long. The natural carbon cycle moves carbon from the atmosphere to plants and eventually to plant consumers rather quickly. So an approach that uses photosynthesis hast to, essentially, never stop, which is fine because there’s a constant need for food.
Over the last few hundred years, the human population on the planet has exploded so that it’s not possible for any large group of people to lead a nomadic existence as our ancestors did. The land has been claimed and some parts are used for growing food while others may be used for cities or for dwellings and other human activities.
The tough part of climate change, given our population, is that it threatens to make farm land un-farmable moving growing regions and disrupting civilization in the process.
Another difficulty in trying to figure out how much atmospheric carbon we can tolerate has to do with how green plants turn inorganic CO2 into the foods we eat. Carbon moves in a continuous cycle from inorganic CO2 to green plants that turn it into organic material, some of which is food while some is simply plant material like leaves, branches, roots, etc. Call it all biomass. At some point animals might eat the food to satisfy their energy needs and in the process the food is converted back into CO2 and water.
Today we also get a lot of carbon from fossil fuels that were formed millions of years ago and sequestered from the rest of the world. This process is still ongoing but it can take millions of years.
One possible solution to the climate problem might be to treat the problem as a chronic need rather than an acute one. An acute need is an emergency that has to be solved at once without delay. On the other hand a chronic problem is always there and requires management.