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By 2050, nearly three-quarters of humanity will reside in countries with below-replacement fertility. This nearly global shift has had enormous demographic, economic, and strategic implications. European importance has diminished (in 1900 the continent had about 18 percent of the world’s population; in 2020 it has only 9.5 percent) and Asia has ascended (60 percent of the world total in 2020), but regional high fertilities guarantee that nearly 75 percent of all births during the 50 years between 2020 and 2070 will be in Africa.
For every dollar invested in vaccination, $16 is expected to be saved in healthcare costs and the lost wages and lost productivity caused by illness and death.
The verdict is clear: no other combustion machines combine so many advantages as do modern gas turbines. They’re compact, easy to transport and install, and relatively silent, affordable, and efficient, offering nearly instant output and able to operate without water cooling. All this makes them the unrivaled machine to supply both mechanical energy and heat.
This is good news, because PV cells have a higher power density than any other form of renewable energy conversion. Even as an annual average they already reach 10 watts per square meter in sunny places, more than an order of magnitude higher than biofuels can manage. And with rising conversion efficiencies and better tracking, it should be possible to increase the annual capacity factors by 20–40 percent.
Perhaps the best long-term hope is to utilize cheap solar electricity to decompose water by electrolysis and use the produced hydrogen as a multipurpose fuel, but such a hydrogen-based economy is not imminent.
The conclusion is obvious. To have an electric ship whose batteries and motors weighed no more than the fuel (about 5,000 tons) and the diesel engine (about 2,000 tons) in today’s large container vessels, we would need batteries with an energy density more than 10 times as high as today’s best Li-ion units.
The most impressive illustration of China’s unprecedented construction effort is that in just the last two years the country emplaced more cement (about 4.7 billion tons) than the US did cumulatively throughout the entire 20th century (about 4.6 billion tons)!
Both in the United States and in the European Union, buildings account for about 40 percent of total primary energy consumption (transportation comes second, at 28 percent in the US and about 22 percent in the EU). Heating and air conditioning account for half of residential consumption, which is why the single best thing we could do for the energy budget is to keep the heat in (or out) with better insulation.
