No quick switch to low-carbon energy: in the first of two pieces on reducing greenhouse-gas emissions, Gert Jan Kramer and Martin Haigh analyse historic growth in energy systems to explain why deploying alternative technologies will be a long haul
To combat climate change, the world's entire energy system needs a major overhaul before the middle of the century. But can we build new energy supplies that quickly? Some argue that with the right incentives we can see similar rates of change in the energy system as have been seen in information technology. So most of the debate focuses on how much the transition will cost and who will foot the bill. Here, we argue that cost is less important than the rate at which existing low-carbon energy technologies can be physically deployed. Because the scale of the energy system is so huge, it takes time to build the human and industrial capacity to achieve substantial deployment.
There have been high-profile proposals to 'repower' the world in a decade, loosely based on the way innovative consumer goods such as mobile phones or iPods conquer their markets1,2. Unlike with consumer goods, we believe that there are robust empirical 'laws' that limit the build rate of new and existing energy technologies and thereby the potential to deliver much of the hoped-for transformation by 2050 (ref. 3). To accelerate deployment, policy-makers need to tailor their policies to specific technologies in ways that recognize the stage of development.
In the twentieth century, it took 30 years for energy technologies that were available in principle to grow exponentially and become widely available (Fig. 1). This reaching 'materiality' can be defined as delivering about 1% of the world's energy mix. After that, the growth becomes linear until the technology captures its final market share. This pattern is remarkably consistent across energy technologies and the two growth phases can be seen as the 'laws of energy deployment' (see 'The laws of energy-technology deployment'). Policy-makers concerned about carbon dioxide emissions will want to accelerate the first phase, making energy technologies 'material' within one decade instead of three. But we see two fundamental reasons why the exponential growth in the early, pre-material phase will be hard to beat.
First, scale-up means learning by doing, which takes time in the energy industry. Where energy technology relies on conversion processes--as with next-generation nuclear energy, biofuels or carbon capture and storage (CCS) --historically it has taken three years to build a demonstration plant, one year to start it up and two to five years to overcome setbacks and reach satisfactory operability. So it can take a decade to reach the point where one is confident enough to build the first full-scale commercial plant. It can take another decade to build a dozen.
Where energy technology relies on conversion devices--wind energy, for example--scale-up is equally time-consuming. From 1993 to 2007, worldwide electricity from wind grew at more than 25% a year, in agreement with the first law. Almost two-thirds of this growth comes from more-powerful turbines. In the mid-1980s, 50-kilowatt wind turbines delivered an annual total of 1,000 terajoules (TJ)....
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