I check my phone. “Already inside, some good ales on.” I quickly flick my wallet open to see a £20 note, then open the door to my local pub. A wave of warm air, infused with familiar and somewhat questionable odours, washes over me. An evening of chatter and drinking with friends awaits. Unexpectedly, the pub has a promotion running, and I’m handed a voucher for a free drink as I walk in.
Here’s the question: over the course of the evening, will I now drink the same amount, or more, than I otherwise would have?
It’s a simple question. Let’s say I intended to get three pints of beer. Will I now get a free extra drink, and thus consume four pints, or substitute the free drink for one I’d buy?
I’m sure you can think of ways of answering this kind of question in a scientific way. Perhaps we could give a random selection of people vouchers and compare how many drinks they buy, on average, to people without vouchers. Understanding why they behave that way is much more complicated. Without asking why, though, we can’t begin to generalise and predict what might happen in other promotions, in other situations, with other resources.
Two recent studies have tried to answer a question like the one I posed, but at a much bigger scale. Candice Moy, in Geographical Research, examined whether owning a rainwater tank changes how people react to water becoming more scarce during a drought. More recently, Richard York, in Nature Climate Change, analysed whether development of renewable energy displaces fossil fuel energy, or simply adds to it. In other words, do rainwater tanks and renewable energy supplies function as extra resources, or substitute for resources in our existing systems?
Let’s jump straight in with what they found. People with rainwater tanks, when asked to conserve mains water, reduced their average consumption by the same amount as people without tanks. And, in a one-two punch, York found that renewables displace fossil fuels at a far lower than 1:1 ratio.
How can this be? If a person has a rainwater tank, surely they can afford to cut back much more than someone without? And if we are building new, clean energy sources, surely we can shut down our dirty fossil fuel plants? The questions only make sense if we view the tanks and renewables as substitutes for what we’d otherwise use. Clearly, that’s not what is happening.
Moy’s rainwater tank study dug deeper into the motivations of the people in her study. She explains how our relationship with water – how we use it, how we value it – is hugely complex. The social expectation to have clean, washed clothes, or a green lawn, can push us to consume more, while our concern for local rivers or rising water costs can drive our consumption down, and it is the balance of all of these factors that adds up to our water use.
In the study, Moy identified three key groups of rainwater tank owners. One used the tanks as a way to maintain their existing consumption habits, even when they were asked to reduce consumption. They valued their ability to consume water freely, and a tank is a tool to bypass restrictions on mains consumption. The second group identified with the conservation argument, but didn’t actually change their consumption habits. The third group were frugal users, and were able to achieve large reductions in mains water consumption with the help of the tank.
What this tells us is that the presence of an additional, ‘free’ resource supply only reduces consumption from the existing resource pool when we actively use it as a substitute. Building water tanks must be accompanied by the intention to cut back on mains water use, otherwise consumption won’t change.
York’s paper tells a similar story. He looked at global trends in energy supplies (for example, solar, nuclear, coal, etc.). In short, he found that for each unit of renewables added to the energy supply system, less than one quarter of a unit of fossil fuel energy was displaced. In other words, most renewable energy sources are added as extras, not substitutes.
It’s an important finding, because it discredits the argument that we simply need to invest more in renewable energy to reduce fossil fuel use. In the same way that Moy’s paper shows that buying everyone a rainwater tank won’t eliminate our need for a mains water supply, York’s paper tells us that building lots of wind farms won’t quickly reduce our greenhouse emissions.
That’s not because renewable energy can’t reliably supply most of our energy needs. It can. It’s because there is no current reason for the energy industry to cut back on fossil fuel energy sources. There’s huge existing investment in the infrastructure to use fossil fuels and that creates massive inertia in the system. York concludes that “direct suppression of fossil-fuel use (for example, by a carbon tax) is likely to be much more effective at reducing fossil-fuel use than simply expanding non-fossil-fuel energy sources”.
It’s a crucial distinction, and one we need to keep in mind when we decide on the action we’re going to take in the future. We don’t need extra renewable energy. We need to actively substitute renewable resources for existing unsustainable sources, and complement that with demand reduction and better efficiency. Market forces will only do this if they are pushed in the right direction by price signals. Let’s make sure that, when governments announce renewable energy targets, they also legislate for carbon cuts. Without it, we’re facing an immense planetary hangover.
MOY, C. (2012). Rainwater Tank Households: Water Savers or Water Users? Geographical Research, 50 (2), 204-216 DOI: 10.1111/j.1745-5871.2011.00720.x
York, R. (2012). Do alternative energy sources displace fossil fuels? Nature Climate Change, 2 (6), 441-443 DOI: 10.1038/nclimate1451