The future of energy is likely to look more like the past: a gradually evolving mix of energy sources that don’t transform suddenly overnight, but instead evolve as new sources of energy prove themselves for new uses.
Matthew Boulton, of the 18th-century engineering firm Boulton & Watt, once boasted of his company’s steam engines, “I sell here, sir, what all the world desires to have: power.” He and James Watt had demonstrated the ultimate meaning of Francis Bacon’s famous dictum “Knowledge is power.” Watt’s knowledge of the science of energy made it possible to create a transformative new source of power.
What is the new knowledge that is likely to create new sources or supplies of energy in the future?
There is no shortage of intriguing suggestions. Take tidal power. The Earth is circled by a giant generator called the Moon, which is constantly moving the oceans up and down as it passes. There is certainly an enormous amount of energy there, if we can harness it, and there have been a few successful experiments.
Or consider reverse osmosis: a process that uses the chemical difference between saltwater and freshwater to generate energy, which has also been the subject of relatively small-scale experiments.
There are even schemes for vast solar arrays in space, with the energy converted to microwave radiation and beamed back down to Earth, a technology that recently had a successful test.
With each of these proposals, you may notice that there’s a catch. There’s a long distance from a theoretical breakthrough to a technology with predictable costs that justifies enormous investments in new energy infrastructure. With tidal power and reverse osmosis, for example, there have been demonstration projects, but on a scale of kilowatts and megawatts in a world where energy is consumed by the gigawatt. As for space-based solar, consider the enormous costs of sending equipment into space and maintaining it. (Hint: What is the most expensive structure ever built? The International Space Station.) Moreover, a lot of these new ideas are geographically limited, dependent on proximity to a location that provides the right conditions. That is what has limited an older, well-established form of alternative energy, geothermal. It’s great for Iceland, not so much for Kansas.
All of these issues are summed up in the fastest emerging of the new energy technologies: solar power. “Renewable energy” like wind and solar is still used on a relatively small scale. Wind is 3.7 percent of global electricity generation, solar 1.3 percent. (By far the biggest “renewable” source is the oldest and most established: hydroelectric, at 16.6 percent.)
While the potential of solar power generates a lot of excitement, it is also prone to applications that are more symbolic than practical. Take Elon Musk’s latest announcement about attractive-looking solar roof tiles, which was silent on one big issue. How much do they cost? Pro-tip: When somebody launches a big new product and doesn’t tell you how much it will cost, the answer to that question is not going to good.
Yet solar power actually is growing in practicality. Over time, the cost of panels has been declining while their power yield has increased. There is a kind of Moore’s Law for solar, in which “the cost of solar power drops by about 20 percent with every doubling of installations.” Trends tend to continue until they don’t, so the improved economics of solar power is not inevitable. But still, a projection of actual current trends into the future is a lot better than mere speculation.
That’s not the real challenge, though. The big obstacle to wind and solar is energy storage. There has been a lot of breathless news recently about new installed capacity of these power sources outpacing new fossil fuel capacity. The catch is that term “capacity.” Wind and solar installations operate at a fraction of their total capacity because the sun doesn’t always shine and the wind doesn’t always blow. And because their source of power is variable, they require traditional backup generation capacity to fill in when they can’t meet demand.
That’s why a lot of the hope for making solar energy more practical rests on advances in battery technology. Tesla, for example, is already building a giant battery storage facility for Los Angeles. Again, this depends on a projection into the future of current trends: The cost of batteries has been decreasing while their “energy density”—the amount of power you can store in a given weight of battery—has been increasing.
There are three basic issues with battery storage: energy density, recharge times, and the total battery life cycle. Energy density and recharge times are the biggest issues keeping electric cars from being competitive with the internal combustion engine. Batteries have one-tenth the energy density of gasoline and take hours to charge, while you can refill a gas tank in a few minutes and be on your way. Then there is the life cycle. If you are reading this, you almost certainly use at least one device with a lithium-ion battery, and you are very familiar with its decreasing ability to hold a charge after repeated use, so that a cellphone battery that used to last most of the day is suddenly in constant danger of running low.
There are several radical new battery technologies that address these issues. New metal-air batteries might be able to carry an energy density as a high as gasoline. New graphene supercapacitors might be able to charge in much shorter times and can be charged again and again indefinitely. Theoretically.
There’s the rub, and it’s an issue that we see again and again with emerging future energy sources: There’s always a breakthrough that we’re still on the other side of. Based on past experience, we can assume that eventually some of these breakthroughs will arrive. But we don’t know which ones and, crucially, we don’t know how long it’s going to take or how much it’s going to cost.