Work.

What do we think of when we hear the term ‘work’?

Most likely we’d consider it to be what we do for a living, our exchange of labour in return for money however there is another way of considering the meaning of the word ‘work’ and that is the physics definition as being ‘work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, for a constant force aligned with the direction of motion, the work equals the product of the force strength and the distance traveled.’

Work is how we do things, how we make things, how we move things, produce and build things, this form of mechanical work involves the expenditure of energy beyond the metabolic ‘work’ or enenergy usage of the body at rest as even at rest the body has to use energy to just to maintain homeostasis.

Homeostasis is the energy requirement of the body at rest, even if no physical activity is being consciously engaged the body continually works to maintain life and this work uses energy. At rest, the body engages in a complex array of activities to maintain homeostasis, a dynamic state of equilibrium essential for survival. Cells continuously convert nutrients into energy through metabolic processes like glycolysis, the citric acid cycle, and oxidative phosphorylation. This energy fuels cellular maintenance, repair, and synthesis, ensuring the integrity and functionality of every cell.

Thermoregulation is a critical function, where the body regulates its internal temperature through mechanisms such as vasodilation, vasoconstriction, sweating, and shivering. These processes involve the autonomic nervous system and require energy to maintain a constant core temperature.

The circulatory system, driven by the heart, operates continuously to pump blood throughout the body. This ensures the delivery of oxygen and nutrients to tissues and the removal of metabolic waste products. The smooth muscles in blood vessels adjust their diameter to regulate blood pressure and flow, maintaining circulatory homeostasis.

Respiration, involving the diaphragm and intercostal muscles, facilitates the exchange of oxygen and carbon dioxide. This process is vital for cellular respiration and metabolic functions. The nervous system maintains neuronal activity, ensuring communication between the brain and peripheral tissues. This involves maintaining resting membrane potentials and transmitting action potentials, both energy-intensive processes.

Kidney function is paramount in filtering blood, regulating electrolyte balance, and maintaining fluid homeostasis. The kidneys' active transport mechanisms consume significant energy to perform these tasks effectively. The endocrine system produces and regulates hormones, orchestrating various physiological processes. Hormone synthesis, release, and feedback regulation are tightly controlled and energy-dependent.

The immune system remains active even at rest, surveilling for pathogens and repairing tissue damage. White blood cells and other immune components continuously patrol the body, ready to respond to threats. Collectively, these processes constitute the body's basal metabolic rate, the minimum energy expenditure required to sustain vital functions while at rest. Maintaining homeostasis involves the integrated efforts of multiple physiological systems, each playing a crucial role in preserving the body's internal stability.

For us humans it appears that we use and burn vast amounts of energy to do our work and all of that comes of course from the foods we eat but this amount of work pales into statistical insignificance compared to the work we employ by other means.

A single barrel of oil contains 42 gallons (approximately 159 litres) and holds about 5.8 million British thermal units (MBtus) or 1,700 kilowatt-hours (kWh) of energy. This amount of energy is equivalent to 12.5 years of human labor, assuming a very fit and healthy person working full capacity for 40 hours a week.

In 2016, the world consumed 35,442,913,090 barrels of oil, averaging 97,103,871 barrels per day.

This annual consumption translates to approximately 44 billion years of human labor, the universe is 13.7 billion years old, this is one year of oil usage.

The ‘work’ equivalent of just a single barrel of oil is a loaded car travelling form London to Parma in Italy

This is considered to be 12.5 years of hard human labour working a 40 hour week.

When spread across the global population of 8.2 billion people, this equates to an annual usage of 5 barrels of oil (198 gallons) per person. Consequently, each year, every individual on the planet—from infants to the elderly—utilises energy equivalent to 62.5 years of human labor, of oil alone.

Another way to consider this is by examining the energy output of a barrel of oil. A single barrel yields about 20 gallons of petrol, along with other energy-rich distillates. Focusing solely on the petrol, and assuming an average UK car achieves 40 MPG, this amount of fuel would take you roughly from London to Parma in Italy. However, this isn't just you traveling—it's you, the car, and your luggage as well as potentially 3 or 4 other passengers. Now, imagine pushing a fully loaded car this entire distance over France and the Swiss Alps! This provides a tangible sense of the 'work' equivalent contained in a single barrel of oil.

Fossil fuels are using the same type of stored sunlight that we use to feed ourselves

Using fossil fuels means tapping into energy stored through the same biochemical processes that produce our food. Just as all our food is ultimately linked to the food web through photosynthesis, where sunlight captures carbon dioxide and converts it into long chains of sugars, the energy stored in fossil fuels follows a similar pathway.

Photosynthesis is the foundational process where plants, algae, and certain bacteria convert sunlight into chemical energy. This process involves capturing carbon dioxide from the atmosphere and water from the soil to produce glucose (a simple sugar) and oxygen:

PHOTOSYNTHESIS

6CO2​+6H2​O+light energy→C6​H12​O6​+6O2​

The glucose produced can be used immediately by the plant for energy, stored as starch, or used to build other organic molecules, such as cellulose. This glucose forms the base of the food web, providing energy to herbivores, which in turn provide energy to carnivores or omnivores.

FOSSIL FUEL BURNING

We might think that we’re very different from an internal combustion engine but essentially we also run on internal combustion, both forms of fuel are carbon based stored energy that is released though combination with oxygen

COMBUSTION & RESPIRATION

Fossil fuels, such as coal, oil, and natural gas, originate from ancient organic matter—primarily plants and microorganisms—that lived millions of years ago. These organisms captured solar energy through photosynthesis, just as modern plants do. Over time, the organic matter was buried under layers of sediment, subjected to heat and pressure, and transformed into fossil fuels. This geological process effectively locked away ancient solar energy in chemical form.

When we burn fossil fuels, we release this stored energy through combustion, a process similar to cellular respiration in living organisms. Combustion involves the oxidation of hydrocarbons (carbon-based molecules) in the presence of oxygen to produce carbon dioxide, water, and energy:

BURNING FOSSIL FUELS

CH4​+2O2​→CO2​+2H2​O+energy

The equation above shows how the burning of fossil fuels creates energy with by products of combustion being CO2 and water, the same as caused by respiration below.

RESPIRATION IN OUR BODIES

In cellular respiration, glucose is oxidised in a series of biochemical reactions to produce carbon dioxide, water, and energy, captured as adenosine triphosphate (ATP):

C6​H12​O6​+6O2​→6CO2​+6H2​O+energy (ATP)

Both processes—combustion of fossil fuels and cellular respiration—involve breaking chemical bonds and forming new ones, releasing energy in the process. This released energy powers our cars, heats our homes, and fuels industrial processes, much like ATP provides energy for cellular functions.

The biochemical processes that produce our food and those that stored energy in fossil fuels are fundamentally similar. Both rely on photosynthesis to capture solar energy and convert it into chemical energy, which is then released through oxidation. The critical distinction lies in the timescale and environmental impact of releasing ancient carbon stores through fossil fuel combustion.

The significant difference is the timescale. The energy in fossil fuels was captured and stored millions of years ago, while the energy in our food is part of a continuous, short-term cycle. When we burn fossil fuels, we release carbon dioxide that was removed from the atmosphere eons ago, contributing to the current increase in atmospheric CO2 levels and impacting climate change.

Roughly 10 percent of the oil that's harvested today was formed during the Paleozoic age, which fell between 541 and 252 million years ago. Most of it formed during the Mesozoic era, which happened between 252 and 66 million years ago. The final 20 percent formed during the Cenozoic age, roughly 65 million years ago - we’re borrowing energy from the past.

When we consider the difference in perceived energy usage using the example above of pushing versus driving a 2 tonne car from London to Parma we start to get an idea of the staggering amount of energy that we have benefitted from by using fossil fuels.

Estimating the total energy used from fossil fuels to date involves aggregating historical data on the consumption of coal, oil, and natural gas. The following figures provide a comprehensive estimate:

HOW MUCH HAVE WE USED TO DATE?

Oil Consumption: According to historical data, approximately 1.3 trillion barrels of oil have been consumed since the start of the industrial age.

Coal Consumption: The cumulative consumption of coal from the start of the industrial age to the present is estimated at around 700 billion tonnes.

Natural Gas Consumption: Historical data estimates that around 3,000 trillion cubic feet (TCF) of natural gas have been consumed. One cubic foot of natural gas contains about 1,000 British thermal units (BTUs), which converts to approximately 0.293 kWh:

This rough calculation suggests that humanity has used approximately 4,811 trillion kilowatt-hours (kWh) of energy from fossil fuels to date. Lets put that figure back into a human perspective.

To translate the total fossil fuel energy consumption into terms of human work, we can use the conversion that 1 kilowatt-hour (kWh) of energy is equivalent to about 3.6 million joules (MJ), and an average human working at full capacity produces roughly 100 watts (W) of power. This translates to 0.1 kilowatt-hours per hour of work. So, 4,811 trillion kilowatt-hours of energy is equivalent to approximately 24.055 trillion years of human work.

Lets continue the number journey… approximately 12.9 billion people have lived since the significant use of fossil fuels began around 1750.

This is a rough estimate and actual numbers could vary based on different historical population data and growth models. So if we take the human equivalence of energy. So, 24.05524 trillion (total human work years of fossil fuel energy) divided by 12.9 billion (people who have lived since the advent of fossil fuels) we can get a figure that relates to the amount of extra ‘work’ that been done by fossil fules per person since 1750 and this roughly equates to

1,864 YEARS

Its hard for us to imagine the world without not just the products and infrastructure that fossil fuels have built but more importantly the ‘work’ that their use in human terms has provided for us as at least 1800 times what a human can achieve in year per person. This availability of energy has built our cities, our transport net works and to a large degree our global food system but it has come at a cost. We have chosen to borrow energy from back in time and now we need to replace it.

OIL GAS AND COAL BUILT OUR CIVILISATION - WE SHOULD BE THANKFUL AND MOVE ON

The utilisation of fossil fuels has been a fundamental force in shaping modern civilisation. This transformative energy source, embedded in the Earth's crust, has fuelled the great engine of progress, propelling humanity into an era of unprecedented growth and innovation. While it is tempting to look back and lament the mistakes made along the way, we should also be eternally grateful for the conveniences it has afforded us. For instance, consider that a mere century ago, the luxury of a hot shower each morning was unimaginable. Fossil fuels have undeniably enhanced our quality of life, bringing comforts and advancements that define modern living.

In the twilight of the 18th century, the Industrial Revolution dawned, heralded by the harnessing of coal to power steam engines. This marked the birth of a new age where machinery could perform tasks once reliant on human and animal labour, thereby amplifying production and ushering in an era of mass industrialisation. Cities swelled with life as rural dwellers flocked to urban centres in search of work, catalysing a profound shift in societal structures and laying the groundwork for the modern metropolis.

The advent of crude oil and the subsequent development of the internal combustion engine revolutionised transportation, rendering distances malleable and the world more interconnected. The automobile, a symbol of personal freedom and mobility, and the airplane, a marvel of human ingenuity, shrank the globe, enabling the swift movement of people and goods. Maritime trade, powered by oil-fuelled vessels, bridged continents, facilitating a global exchange of resources and culture.

Electricity, generated primarily from coal and later natural gas, illuminated homes, powered factories, and electrified the world. This reliable and ubiquitous energy source underpinned the growth of modern infrastructure, transforming the rhythms of daily life and fuelling economic expansion. The proliferation of industries, made possible by the steady flow of fossil fuels, spurred technological advancements that propelled humanity forward, fostering an era of unprecedented innovation and discovery.

The economic landscape, too, was reshaped by the energy unleashed from fossil fuels. Industrial production soared, economies flourished, and job markets expanded, providing livelihoods and elevating standards of living. The very fabric of modern society was woven with threads of oil, coal, and gas, each strand contributing to the tapestry of human progress.

THE FUTURE

Maths to show how the entire history of fossil fuel usage on planet earth compares to the energy emitted by the sun.

The problem with fossil fuel usage is simple and obvious, we’ve borrowed energy from the past and used it in a compressed time frame that is way quicker than it was produced, this has happened at such a pace that natural system, cannot rebalance and re-use the carbon as fast as we’re releasing it.

The problem is simply one of time, had we used fossil fuels at the same rate they were produced we would likely have not caused any problems at all but by doing so our expansion and growth has happened on a very short timescale.

The good news is that now that we have created this global infrastructure of connection we can use it to share solutions which really are simple once we accept a very basic concept and that is that we should only be using energy at the rate is produced. No more borrowing from the past or the future.

After all, the total energy we have used from fossil fuels at 1.3 trillion barrels is 7.492x10 power 21 joules which is the energy output of the sun every 0.0000209 seconds, there’s enough potential for the work we need to go around, we just have to use it.