Sustainable Energy - without the hot air

1. Numbers, not adjectives, are essential for understanding energy.

To make this comparison, we need numbers, not adjectives.

Avoid innumerate codswallop. Public debates about energy are often emotional and lack quantitative grounding. People use vague terms like "huge" or "little" without comparing them to actual consumption needs. This allows misleading claims to proliferate, from ineffective personal actions like unplugging phone chargers to exaggerated claims about renewable potential or the impact of minor activities.

Focus on scale. Understanding the relative scale of energy sources and uses is critical. Knowing that something is "huge" is insufficient; we need to know how it compares to our "huge" consumption. Using consistent, relatable units like kilowatt-hours per day per person helps make these comparisons clear and memorable, cutting through the confusion.

Arithmetic is key. Evaluating energy policies requires simple arithmetic, not just opinions or feelings. By quantifying consumption and potential production, we can determine which proposals actually "add up" and which are based on wishful thinking or misinformation. This book aims to provide the tools and numbers for readers to perform this essential analysis themselves.

2. Our current energy consumption is huge and diverse.

The quest for safe, secure and sustainable energy poses one of the most critical challenges of our age.

High consumption levels. The average person in developed countries consumes a significant amount of energy daily. For example:

• Average European: ~125 kWh/d
• Average American: ~250 kWh/d
• Typical affluent person (estimated): ~195 kWh/d

Diverse energy uses. This consumption is spread across many activities, not just electricity. Major categories include:

• Transport (cars, planes, freight)
• Heating and cooling (buildings, water)
• Manufacturing and "stuff" (embodied energy in goods)
• Lighting and gadgets
• Food and farming
• Public services (defence, infrastructure)

Fossil fuel reliance. Currently, the vast majority of this energy comes from fossil fuels (oil, gas, coal). This reliance is the root cause of concerns about sustainability, security of supply, and climate change. Transitioning away requires addressing consumption across all these diverse sectors.

3. Renewable sources are diffuse and require country-sized areas.

Renewable facilities have to be country-sized because all renewables are so diffuse.

Low power density. Unlike concentrated fossil fuels, renewable energy sources are spread out over large areas. Their power density (energy captured per unit area) is relatively low:

• Onshore wind: ~2 W/m²
• Offshore wind: ~3 W/m²
• Solar PV (UK): ~20 W/m² (panels), ~5 W/m² (farm)
• Energy crops: ~0.5 W/m²
• Tidal stream: ~6 W/m²
• Tidal pool: ~3 W/m²

Vast areas needed. To generate power comparable to our current consumption from these diffuse sources requires covering enormous areas of land or sea. For example, providing just 20 kWh/d/p from onshore wind in the UK would require covering 10% of the country with wind farms. Similarly, significant solar or biomass contributions demand areas the size of Wales or even larger.

Scale is the challenge. The sheer scale of the infrastructure needed for a renewable-only energy system is often underestimated. It involves industrializing large parts of the environment, which faces significant social and environmental hurdles, even before considering economic costs.

4. Domestic renewables alone cannot meet current demand without massive societal change.

To sustain Britain’s lifestyle on its renewables alone would be very difficult.

Production vs. Consumption. Even when adding up the maximum conceivable potential from domestic renewables like wind, solar, hydro, wave, tide, and biomass, the total often falls short of current consumption levels. For the UK, this theoretical maximum is around 180 kWh/d/p, barely matching a typical affluent person's consumption and falling short of the average American's.

Ignoring constraints. This theoretical potential often ignores practical limitations. Factors like economic feasibility, social acceptance (NIMBYism), environmental impact, and competition for land use (e.g., food vs. energy crops) drastically reduce the plausible contribution from domestic renewables.

The "Saying No" problem. Public opposition to large-scale renewable projects (wind farms, tidal barrages, solar farms) severely limits deployment. If every proposed project is met with resistance, the plausible domestic renewable contribution shrinks dramatically, making it impossible to meet current demand without other sources or significant demand reduction.

5. Transport and heating are major consumption areas ripe for efficiency gains.

The top two categories are transport and heating (hot air and hot water).

Dominant energy sinks. Transport and heating together account for a large portion of total energy consumption. In the UK, official statistics show these are the two biggest categories of end-use energy demand.

Inefficiencies exist. Current technologies for transport and heating, particularly those relying on fossil fuels, are often highly inefficient:

• Petrol/diesel cars: Only ~25% of fuel energy is used for motion; the rest is lost as heat.
• Standard boilers: Lose heat up the chimney.
• Buildings: Lose heat through poor insulation and draughts.

Potential for reduction. Understanding where energy is lost reveals opportunities for significant savings. Reducing demand through efficiency measures is a critical part of any sustainable energy plan, potentially halving or more the energy needed for these sectors before even considering fuel source.

6. Electrification and heat pumps offer significant demand reduction and decarbonization.

Heat pumps are roughly four times as efficient as a standard electrical bar-fire.

Efficient conversion. Electric motors are much more efficient than internal combustion engines (~90% vs ~25%). Electrifying transport can drastically reduce the energy needed per kilometer. Similarly, heat pumps use electricity to move heat, delivering 3-4 units of heat for every unit of electricity consumed, far more efficient than direct electric heating or even burning fuel.

Decarbonization pathway. Electrification provides a clear path to decarbonizing transport and heating, provided the electricity itself comes from low-carbon sources (renewables, nuclear, clean fossil). This shifts the challenge from multiple fuel types to primarily electricity generation.

Increased electricity demand. This strategy, however, leads to a substantial increase in overall electricity demand. Powering transport and heating with electricity could nearly triple current electricity consumption, requiring a massive build-out of low-carbon generation capacity.

7. Nuclear fission offers large, low-carbon power but has challenges.

The material streams flowing into and out of nuclear reactors are small, relative to fossil-fuel streams.

High power density. Nuclear fission power stations deliver a large amount of power from a small amount of fuel. The material flows (fuel in, waste out) are orders of magnitude smaller than those for fossil fuels, reducing mining, transport, and waste volume issues.

Low-carbon baseload. Nuclear power is a low-carbon source that can provide reliable, "always-on" baseload power, complementing intermittent renewables. It has the technical potential to provide a significant portion of a country's energy needs.

Challenges remain. Despite its advantages, nuclear fission faces significant hurdles:

• Public perception and safety concerns (accidents, security).
• Waste disposal (though small volume, requires long-term secure storage).
• High upfront capital costs and long construction times.
• Sustainability of fuel supply (uranium reserves are limited for current reactor types, but much larger with breeder reactors or ocean extraction).

8. Solar power in deserts offers massive potential via transmission.

All the world’s power could be provided by a square 100 km by 100 km in the Sahara.

Abundant resource. Deserts receive intense, reliable sunlight, making them ideal locations for large-scale solar power generation, particularly concentrating solar power (CSP) which can also store heat. The potential power per unit area (~15 W/m²) is significant.

Scale of potential. While the famous "100km square" claim is an underestimate (it would take a 1000km x 1000km square to power the world at current levels), the total desert area is vast enough to meet global energy needs many times over. For Europe and North Africa, a 600km x 600km area in the Sahara could power a billion people at European consumption levels.

Transmission is key. Harnessing this potential requires efficient long-distance transmission of electricity from sunny desert regions to demand centers. High-voltage direct current (HVDC) lines can transmit power over thousands of kilometers with relatively low losses (~15% over 3500km), making intercontinental energy trade feasible.

9. Fluctuations in supply and demand require storage or flexible loads.

The electricity grid can’t store energy.

Mismatch problem. Electricity supply and demand must be balanced instantaneously. Intermittent renewables like wind and solar fluctuate unpredictably, and demand varies throughout the day and year. Without fossil fuel plants to ramp up and down, other solutions are needed.

Solutions:

• Energy Storage: Store excess energy when supply is high (e.g., pumped hydro, batteries, thermal storage). Pumped hydro is currently the most mature large-scale option, but requires specific geography.
• Demand Management: Adjust demand to match supply (e.g., smart charging of electric vehicles, flexible industrial processes, smart appliances responding to grid conditions).
• Geographic Diversity: Connect widely dispersed renewable sources via a robust grid so that low output in one area is offset by high output elsewhere.

Scale of the challenge. Coping with fluctuations from a large renewable fleet requires storage or flexible demand on a massive scale. For example, managing a multi-day wind lull in the UK could require storing hundreds or thousands of gigawatt-hours of energy. Electric vehicle batteries offer a promising flexible load and distributed storage resource.

10. Getting off fossil fuels requires big changes and substantial investment.

What’s required are big changes in demand and in supply.

Scale of transformation. Transitioning from a fossil fuel economy is not a minor adjustment; it requires a fundamental transformation of infrastructure, technology, and potentially lifestyle. This involves:

• Replacing entire vehicle fleets with electric alternatives.
• Retrofitting or replacing most buildings for vastly improved insulation and heating systems.
• Building vast new low-carbon power generation capacity (renewables, nuclear, or both).
• Developing and deploying energy storage and smart grid technologies.

Significant investment needed. The cost of this transformation is substantial, running into hundreds of billions or even trillions globally. However, putting these costs in perspective reveals they are comparable to other large societal expenditures:

• Annual global arms spending: ~$1.2 trillion
• Cost of recent wars: Trillions
• Cost of bailing out banks: Trillions
• Annual spending on non-essential goods (e.g., cosmetics): Billions

Long-term perspective. While the upfront costs are high, they represent an investment in long-term energy security and climate stability, potentially avoiding much larger future costs associated with climate change impacts or fossil fuel price volatility.

11. Action is urgent and requires saying "yes" to something.

We need to stop saying no and start saying yes.

Current trajectory is unsustainable. Despite awareness of the challenges, current actions are insufficient to achieve the necessary reductions in fossil fuel use. Carbon pricing is too low and unstable to drive the required investment in low-carbon alternatives and efficiency.

The "Saying No" barrier. Progress is hampered by widespread opposition to the large-scale projects needed. Whether it's NIMBYism against wind farms or concerns about nuclear power, a general reluctance to accept the necessary infrastructure prevents plans from adding up.

Choices must be made. A viable energy future requires deploying technologies on a scale that will be visible and impactful. There is no single perfect solution, and every option has drawbacks. Society must decide which combination of large-scale renewables, nuclear power, clean fossil fuels (with capture), and potentially imported energy it is willing to accept, alongside significant demand reduction. Inaction is effectively saying "yes" to continued fossil fuel reliance and its consequences.

Last updated: May 26, 2025