IELTS Academic Reading — Practice Test 10

Electricity is unusual among commodities in that it must, for the most part, be used at the very instant it is produced. For a century, grid operators managed this awkward fact by adjusting the output of power stations to track demand, burning more fuel whenever consumption rose and easing off when it fell. Wind turbines and solar panels overturn that arrangement. Their output depends on the weather and the time of day, not on what consumers happen to want; the sun sets whether or not the evening peak has arrived, and the wind drops regardless of the forecast. As renewables come to supply a larger share of electricity, the ability to store energy — to save it when generation exceeds demand and release it when the reverse is true — has moved from a convenience to an outright necessity.

By far the largest quantity of energy stored on the world's grids today sits, quietly, in reservoirs. Pumped-storage hydroelectricity works on a beautifully simple principle: when power is plentiful and cheap, water is pumped uphill into an elevated reservoir; when demand returns, that water is released downhill through turbines to regenerate electricity. The technology is more than a century old, cheap to run and capable of storing enormous quantities of energy for many hours at a time. Its drawback is geography. A suitable site needs two large bodies of water at markedly different heights, close together, and few such places remain unexploited in precisely the densely populated regions that most need new storage. Building them is slow, expensive and frequently opposed by those who live nearby.

The technology that has captured recent attention is the lithium-ion battery — the same basic chemistry that powers mobile phones and electric cars. Its cost has fallen dramatically, by roughly ninety per cent over the past decade, and vast battery installations can now be assembled in a matter of months rather than years, more or less wherever they are wanted. Batteries respond almost instantly, which makes them superb at smoothing brief fluctuations and covering the short, sharp evening peak. But they carry a telling limitation: they are economical only over relatively short periods, typically discharging their full capacity within a few hours. Storing enough energy in lithium-ion cells to carry a city through several still, cloudy days would demand quantities of batteries — and of the scarce metals they contain — that would be ruinously expensive.

This exposes the central difficulty of a grid run largely on renewables. The real challenge is not the daily cycle, which batteries already handle well, but the long lulls — the windless, sunless spells that can stretch across several days or even a week — together with the seasonal mismatch between abundant summer sunshine and heavy winter demand. Bridging these gaps calls for what engineers term 'long-duration' storage: systems able to hold energy cheaply for days on end, even if they charge and discharge comparatively slowly. A crowded field of competing candidates has emerged. Flow batteries store their energy in tanks of liquid whose volume can simply be increased to extend how long they last; other schemes propose pumping air into sealed underground caverns under great pressure, or hoisting heavy weights aloft to be dropped through generators when power is required.

The most ambitious proposal dispenses with batteries altogether. Surplus electricity can be used to split water into hydrogen and oxygen; the hydrogen is then stored — potentially for months, in tanks or even in natural underground formations — and later burned or passed through a fuel cell when electricity runs short. Because a gas can be stockpiled in genuinely enormous quantities, hydrogen is one of the very few options that could smooth the swing between whole seasons rather than merely between day and night. Its weakness is efficiency. So much energy is lost in converting electricity into hydrogen and then back into power that well under half of what goes in comes out again, which makes it, at least for now, a costly way to store each unit of electricity.

It is tempting to ask which of these technologies will ultimately 'win', but the question is probably misconceived. Each is suited to a different task: batteries to the daily peak, pumped hydro and flow batteries to spells lasting a few days, hydrogen to the yawning seasonal gap. A resilient low-carbon grid is likely to draw on all of them at once, in a portfolio carefully matched to the local climate and geography. What will decide the outcome, in the end, is less a technical contest than the design of markets and regulations, which at present reward the provision of energy far more readily than they reward the equally vital service of storing it. Until storing a unit of electricity is valued as highly as generating one, the necessary investment may be slow to arrive.

We like to think of our moral judgements as the conclusions of careful thought. Faced with a difficult choice, the flattering story goes, we weigh the considerations on either side, apply our settled principles and arrive, by reasoning, at a verdict. A growing body of research in psychology suggests that this picture has the sequence backwards. In a great many cases the verdict comes first, arriving swiftly and with striking confidence as a kind of intuition, and the reasoning follows only afterwards, marshalled to defend a conclusion that has in fact already been reached. If that is right, much of what we experience as moral deliberation may be less a process of genuine discovery than one of after-the-fact justification.

Some of the most telling evidence comes from cases in which people's judgements stubbornly resist the very reasons they offer for them. Presented with a scenario in which an adult brother and sister decide, privately and with every precaution, to sleep together once and never again, most people declare the act plainly wrong. Yet when their stated objections — the risk of a child, of lasting emotional harm — are removed one by one by the careful design of the story, they do not revise their verdict. Instead they grope for further reasons, and, failing to find any that survive scrutiny, fall back on insisting that it is simply wrong even though they cannot say why. The psychologist Jonathan Haidt named this curious condition 'moral dumbfounding': the judgement stands firm while its supposed grounds quietly collapse.

Haidt built such findings into an influential account he called the social intuitionist model. On this view, moral judgement is primarily the product of fast, automatic intuitions — gut feelings shaped by emotion, culture and our evolutionary past — while conscious reasoning is largely a servant of these intuitions rather than their master. Its role, he argued, is chiefly a social one: we reason not so much to work out privately what we ought to think as to persuade other people, and to assemble after the fact a respectable public case for what we already feel. Reason, in his memorable image, is not the judge who weighs the evidence and reaches a verdict, but the press secretary, issuing confident statements on behalf of decisions that were taken somewhere else.

A related but distinct line of work suggests that the mind contains not one moral system but two, pulling in different directions. Studying the notorious 'trolley problem' — is it permissible to sacrifice one person in order to save five? — the neuroscientist Joshua Greene found that people answer very differently depending on how exactly the sacrifice is carried out. Diverting a runaway trolley by flipping a distant switch strikes most respondents as acceptable; shoving a large man off a footbridge into its path, to precisely the same numerical end, strikes most as monstrous, even though the arithmetic is identical. Brain imaging, Greene reported, showed that the up-close, physical version engaged regions associated with emotion, whereas the impersonal version drew more heavily on areas linked to deliberate calculation. Our judgements, on this reading, are a kind of tug-of-war between an intuitive, emotional response and a slower, more coldly utilitarian one.

Not everyone is persuaded that reason has been so thoroughly demoted. Critics working in an older tradition, associated with the psychologist Lawrence Kohlberg, point out that people plainly do change their minds about moral questions, sometimes through sustained argument alone, and that entire societies have revised their views on slavery, cruelty to animals and the treatment of women in ways that are hard to explain if reasoning were mere window-dressing. Others add a subtler observation: today's swift, effortless intuition may simply be yesterday's hard-won conclusion. A principle reasoned through carefully enough, or absorbed from a culture that once reasoned it through, can sink into the gut and be felt thereafter as an immediate response. On this account, the apparent primacy of intuition may conceal a great deal of reasoning that has merely become invisible with the passage of time.

Which picture is correct matters well beyond the psychology laboratory. If deep moral disagreement is ultimately a clash of intuitions rather than of arguments, then the hope of settling profound disputes by reasoned debate begins to look naive, and those who genuinely wish to change minds might do better to appeal to emotion and shared identity than to marshal evidence. Yet if intuitions really can be reshaped by reasoning, even slowly and by an indirect route, then argument retains its point, and the long historical record of moral change becomes intelligible rather than mysterious. The stakes are considerable for anyone — from schoolteachers to campaigners — whose daily work quietly assumes that showing people good reasons is a way of making them better.

Perhaps the sharp opposition between intuition and reason is itself the deeper mistake. The two are not sealed compartments but constantly feed one another: intuitions supply the raw material that reasoning then examines and tests, and reasoning, over months and across generations, gradually refines the very intuitions it inherits. A single judgement can be immediate in the moment and yet be the slow deposit of long reflection — one's own, or one's culture's. What the recent research most firmly establishes is not that reason is powerless, but that it is rarely the lone, dispassionate arbiter we habitually imagine ourselves to be consulting. The comfortable self-portrait of the purely rational moral agent, weighing each new case afresh from first principles, is the one casualty the evidence leaves beyond repair.