- late 1839–late 1843: Business Activity: -34.3%
- 1836–1838 recession : Business Activity: -32.8%
- 1845–late 1846 recession : Business Activity: -5.9%
- 1847–48 recession: Business Activity: -9.7%
- 1853–54 recession: Business Activity: -8.4%
- Panic of 1857: Business Activity: -23.1%
- 1860–61 recession : Business Activity: -4.5%
- 1865–67 recession: Business Activity: -23.8%
- 1869–70 recession : Business Activity: -9.7%
- Panic of 1873 : Business Activity: -33.6%
- 1890–91 recession : Business Activity: -22.1%
- 1882–85 recession : Business Activity: -32.8%
- Panic of 1893 : Business Activity: -37.3%
- Panic of 1896: Business Activity: -25.2%
- 1899–1900 recession : Business Activity: -15.5%
- 1802–1804 recession: Commodity prices fell dramatically. Trade was disrupted by pirates.
- Depression of 1807
- 1812 recession
- 1815–21 depression: United States entered a period of financial panic as bank notes rapidly depreciated because of inflation following the war. The 1815 panic was followed by several years of mild depression, and then a major financial crisis – the Panic of 1819, which featured widespread foreclosures, bank failures, unemployment, a collapse in real estate prices, and a slump in agriculture and manufacturing.
- 1822–1823 recession: After only a mild recovery following the lengthy 1815–21 depression, commodity prices hit a peak in March 1822 and began to fall. Many businesses failed, unemployment rose and an increase in imports worsened the trade balance.
- 1825–1826 recession:The Panic of 1825, a stock crash following a bubble of speculative investments in Latin America led to a decline in business activity in the United States and England.
- 1828–1829 recession
- 1833–34 recession: The United States' economy declined moderately in 1833–34. News accounts of the time confirm the slowdown. The subsequent expansion was driven by land speculation. Where did this land come from? Is it bad we aren't stealing land from other peoples today?
"Airborne turbines that convert steadier and faster high-altitude winds into energy could generate even more power than ground- and ocean-based units. The study examined the limits of the amount of power that could be harvested from winds, as well as the effects high-altitude wind power could have on the climate as a whole.
Turbines create drag, or resistance, which removes momentum from the winds and tends to slow them. As the number of wind turbines increases, the amount of energy that is generated increases. But at some point, the winds would be slowed so much that adding more turbines will not generate more electricity.
The group found that wind turbines placed on Earth's surface could extract kinetic energy at a rate of at least 400 terawatts, while high-altitude wind power could extract more than 1800 terawatts. Current total global power demand is about 18 terawatts.
At maximum levels of power generation, there would be substantial climate effects from wind harvesting."
Current models, as I understand it, are conflicting in terms of the level of effect of feedback loops. Pulling energy out slows the wind. Slower wind means less energy to pull out, but also localized heating, which likewise makes the location less functional. We are talking orders of magnitudes (yes, plural) regarding disagreement in overall interactive effect, especially between "theoretically possible" and "actually plausible", and "plausible and also non-catastrophic". Without doubt, though, there is a geophysical limit. Also without doubt, somewhere way below the geophysical limit of maximum sustainable drain, there is a region of maximum acceptable ecologic impact. That region is the only region that matters.
Existing estimates of the life-cycle emissions from wind turbines range from 5 to 100
Also of interest: report
"Each wind turbine creates behind it a "wind shadow" in which the air has been slowed down by drag on the turbine's blades. The ideal wind farm strikes a balance, packing as many turbines onto the land as possible, while also spacing them enough to reduce the impact of these wind shadows. But as wind farms grow larger, they start to interact, and the regional-scale wind patterns matter more.
Keith's research has shown that the generating capacity of very large wind power installations (larger than 100 square kilometers) may peak at between 0.5 and 1 watts per square meter. Previous estimates, which ignored the turbines' slowing effect on the wind, had put that figure at between 2 and 7 watts per square meter.
In short, we may not have access to as much wind power as scientists thought.
An internationally renowned expert on climate science and technology policy, Keith holds appointments as Gordon McKay Professor of Applied Physics at the Harvard School of Engineering and Applied Sciences (SEAS) and as Professor of Public Policy at Harvard Kennedy School. Coauthor Amanda S. Adams was formerly a postdoctoral fellow with Keith and is now assistant professor of geography and Earth sciences at the University of North Carolina at Charlotte.
"One of the inherent challenges of wind energy is that as soon as you start to develop wind farms and harvest the resource, you change the resource, making it difficult to assess what's really available," says Adams. But having a truly accurate estimate matters, of course, in the pursuit of carbon-neutral energy sources. Solar, wind, and hydro power, for example, could all play roles in fulfilling energy needs that are currently met by coal or oil. "If wind power's going to make a contribution to global energy requirements that's serious, 10 or 20 percent or more, then it really has to contribute on the scale of terawatts in the next half-century or less," says Keith. If we were to cover the entire Earth with wind farms, he notes, "the system could potentially generate enormous amounts of power, well in excess of 100 terawatts, but at that point my guess, based on our climate modeling, is that the effect of that on global winds, and therefore on climate, would be severe -- perhaps bigger than the impact of doubling CO2."
"The real punch line," he adds, "is that if you can't get much more than half a watt out, and you accept that you can't put them everywhere, then you may start to reach a limit that matters." In order to stabilize Earth's climate, Keith estimates, the world will need to identify sources for several tens of terawatts of carbon-free power within a human lifetime. In the meantime, policymakers must also decide how to allocate resources to develop new technologies to harness that energy. In doing so, Keith says, "It's worth asking about the scalability of each potential energy source -- whether it can supply, say, 3 terawatts, which would be 10 percent of our global energy need, or whether it's more like 0.3 terawatts and 1 percent." "Wind power is in a middle ground," he says. "It is still one of the most scalable renewables, but our research suggests that we will need to pay attention to its limits and climatic impacts if we try to scale it beyond a few terawatts." The research was funded by the Natural Sciences and Engineering Research Council of Canada.