Falling Fertility Rates Could Reshape Energy Demand

Global fertility decline reshapes energy transition planning

Population forecasts have always been central to energy planning. However, new analysis from Wood Mackenzie suggests that falling birth rates worldwide represent far more than a statistical adjustment. The consultancy warns that declining fertility could cause global population to peak at 8.9 billion by 2053 before falling to 7.0 billion by 2100. This demographic shift carries profound implications for long-term energy demand and climate strategy.

For UK businesses planning capital investments in energy infrastructure, these projections matter. Consequently, companies making decisions about renewable capacity, grid expansion, or industrial decarbonisation need to consider whether their assumptions about future demand remain valid. The traditional model of perpetual population growth has underpinned decades of energy forecasting. That model may no longer hold.

Peter Martin, Head of Economics at Wood Mackenzie, describes demographics as destiny for the energy sector. His team argues that falling birth rates are not a tail risk to be monitored passively. Instead, they represent a structural shift that must inform strategic planning now. The window for building transition infrastructure is finite, and demographic decline will eventually impose a lower ceiling on absolute energy demand.

Birth rates fall below replacement across major economies

The global fertility rate reached 2.2 births per woman in 2025. This sits just above the 2.1 replacement ratio needed to maintain population stability without migration. The decline from 2.6 births per woman in 2007 has been swift and shows little sign of reversing.

Wood Mackenzie’s analysis challenges standard UN projections that often assume higher population peaks. Under their low-birth scenario, population contraction begins by 2053. This timeline arrives significantly earlier than many traditional energy models anticipate. Moreover, the decline continues through the remainder of the century, potentially reaching 7.0 billion by 2100.

The drop is most pronounced in advanced economies. Birth rates across Europe, China, and North America have fallen well below replacement levels. South Korea represents an extreme case, with fertility estimated at just 0.7 children per woman. Meanwhile, even regions with historically higher birth rates are experiencing rapid declines as urbanisation and economic development progress.

For businesses, this trend matters because energy demand forecasts have historically assumed growing populations. Therefore, long-term contracts, infrastructure investments, and decarbonisation roadmaps may be based on demand projections that prove too optimistic. Companies that build capacity for a peak population of 10 billion or more could find themselves with underutilised assets.

Population decline reduces absolute energy requirements

Fewer people inherently require less energy, food, materials, transport, and housing. This reduction in absolute demand lowers the total pressure on carbon emissions and resource extraction. Essentially, a stabilising or contracting population makes the net zero goal more achievable by reducing the scale of decarbonisation required.

However, the relationship between population and energy demand is not linear. Electricity demand continues to grow faster than total primary energy use due to electrification trends. Heat pumps, electric vehicles, and industrial process changes all increase electricity consumption even as overall energy intensity may decline. Therefore, grid infrastructure investment remains necessary, though the ultimate capacity required may be lower than current projections suggest.

Critical minerals demand also faces recalibration. The transition to renewable energy requires substantial volumes of lithium, cobalt, rare earths, and other materials. If energy demand peaks sooner due to demographic decline, the intensity of mining required for renewable infrastructure could be lower than anticipated. This does not eliminate supply chain pressures, but it does change the long-term strategic calculus for resource security.

For UK manufacturers and industrial businesses, these shifts present both opportunities and risks. Companies that invested heavily in capacity expansion based on perpetual growth assumptions may face margin pressure. Conversely, businesses that planned conservatively or built flexible capacity may find themselves better positioned. The challenge lies in distinguishing between short-term demand volatility and structural demographic change.

Decarbonisation becomes more manageable but remains urgent

A declining population does not eliminate the need for urgent climate action. Current emissions levels are already causing dangerous warming, and the carbon budget for limiting temperature rise to 1.5°C is nearly exhausted. Nevertheless, demographic decline does alter the scale and shape of the required transition.

Wood Mackenzie’s analysis suggests that the window for building transition infrastructure is narrower than many assume. If population begins declining by mid-century, the business case for certain large-scale projects weakens. For example, new fossil fuel extraction projects with 30-year payback periods may struggle to find sufficient demand in their later years of operation. Similarly, renewable energy projects must be sized for a demand peak rather than indefinite growth.

The economic implications extend beyond energy. Perpetual economic growth has been a core assumption in business planning for generations. That assumption is increasingly challenged by demographic realities. Countries with shrinking working-age populations face slower GDP growth, which in turn affects energy consumption patterns, investment capacity, and the fiscal resources available for climate policy.

For UK SMEs, this creates a strategic dilemma. Businesses must continue decarbonising to meet near-term compliance requirements and customer expectations. At the same time, they should avoid over-investing in capacity that may not be needed in a lower-demand future. Carbon reporting programmes help companies understand their current emissions, but long-term planning requires careful scenario analysis that incorporates demographic trends.

High-consumption lifestyles drive emissions more than population alone

While population size matters, the climate crisis is driven primarily by high-consumption lifestyles in wealthy countries. An additional child born in a high-income nation has a far larger environmental footprint than one born in a low-income country. Therefore, demographic decline in advanced economies carries more weight for emissions reductions than population changes elsewhere.

This distributional reality complicates policy and business strategy. Global population may stabilise or decline, but consumption patterns in growing middle-class populations could still drive emissions upward. China, India, and other emerging economies are adding millions of consumers with rising energy demands. Even if their birth rates fall, the installed base of energy users continues growing for decades.

For UK businesses operating in global supply chains, this means that demand patterns will vary significantly by region. Companies exporting to Asia may still face growing markets, while those focused on Europe or North America confront stagnation or decline. Sustainable procurement strategies must account for these regional differences and the varying carbon intensities of production in different markets.

The sheer reduction in population size still offers a “quiet ally” in reducing total resource extraction and waste. Fewer people means less demand for raw materials, lower agricultural pressure, and reduced waste generation. These effects compound over time, making environmental targets progressively easier to achieve. However, they do not replace the need for immediate action on emissions reductions.

Key facts about demographic trends and energy demand

• Global fertility has fallen to 2.2 births per woman in 2025, approaching the 2.1 replacement level needed for population stability.
• Wood Mackenzie projects population could peak at 8.9 billion by 2053 before declining to 7.0 billion by 2100 under low-birth scenarios.
• Birth rates in South Korea have dropped to approximately 0.7 children per woman, among the lowest globally.
• Electricity demand is expected to grow faster than total primary energy use due to ongoing electrification of transport, heating, and industry.
• A stabilising or contracting population reduces the absolute scale of decarbonisation required to achieve net zero targets.
• High-consumption lifestyles in wealthy countries drive emissions more significantly than population growth in lower-income regions.
• Long-term energy infrastructure investments may face underutilisation if based on perpetual population growth assumptions.

What demographic decline means for business energy strategy

Companies making long-term investment decisions need to integrate demographic scenarios into their planning. Energy-intensive industries face particular pressure to reassess capacity assumptions. If demand peaks earlier than expected, businesses that built excess capacity will face stranded assets and margin erosion. Conversely, companies that under-invest may miss opportunities during the growth phase before demographic decline takes hold.

Scenario planning becomes essential. Businesses should model at least three demographic futures: high-birth continuation of current trends, medium-birth stabilisation, and low-birth decline as outlined by Wood Mackenzie. Each scenario carries different implications for capital allocation, supply chain configuration, and market strategy. Moreover, these scenarios should be updated regularly as fertility data and migration patterns evolve.

For smaller businesses, the challenge is balancing near-term compliance requirements against long-term strategic uncertainty. Regulations like PPN 06/21 for public sector suppliers require carbon reporting and reduction plans regardless of population trends. Therefore, companies must invest in compliance frameworks that meet current standards while remaining flexible enough to adapt as demand patterns shift.

The transition to renewable energy proceeds regardless of population trends, but the scale and timing may adjust. Businesses that locked in long-term renewable energy contracts based on high-growth assumptions may find themselves paying for unused capacity. Conversely, those that built in flexibility or shorter contract terms may benefit from falling prices as supply eventually outpaces demand.

Critical minerals supply chains also face recalibration. If the buildout of renewable infrastructure requires less material than current projections suggest, prices for lithium, cobalt, and rare earths could stabilise sooner. However, near-term shortages remain likely as supply chains struggle to meet even reduced long-term demand. Businesses dependent on these materials should secure supply now while planning for eventual market softening.

Strategic planning in an era of demographic uncertainty

Wood Mackenzie’s analysis challenges the assumption of perpetual growth that has dominated business thinking for generations. For energy-dependent sectors, this shift requires fundamental rethinking of investment horizons, capacity planning, and market assumptions. The transition to net zero becomes more achievable in absolute terms, but the business case for individual projects becomes more complex.

UK businesses face particular challenges due to the country’s already-low birth rate and aging population. Domestic demand for energy may stabilise or decline even as electrification drives changes in how that energy is consumed. Companies serving UK markets must plan for a future of flat or falling total demand, even while electricity consumption grows. This split between total energy and electricity complicates infrastructure planning and requires careful analysis of sector-specific trends.

The implications extend beyond energy to the broader economy. Slower population growth means slower GDP growth, which affects investment returns, lending capacity, and fiscal policy. Businesses that assumed continuous economic expansion may need to revise their growth targets and operational models. In particular, sectors dependent on population growth, such as construction and consumer goods, must adapt to a world of declining headcount.

For SMEs, the message is clear: demographic trends are no longer background noise. They are material factors that should inform strategic planning today. Companies that integrate demographic scenarios into their decision-making will be better positioned to navigate the transition. Those that ignore these trends risk investing in capacity that will never be fully utilised or missing opportunities that arise from changing demand patterns.

Further information is available from authoritative sources. The Department for Energy Security and Net Zero provides policy updates on UK energy strategy. Office for National Statistics population projections offer detailed UK demographic forecasts. The United Nations World Population Prospects publishes global demographic data and projections. These resources help businesses understand the demographic context for their long-term planning and investment decisions.