For almost two centuries, the fossil-fueled energy systems that have powered our economy have been damaging our health and climate. They must be replaced.

Well-intentioned efforts to wean us off fossil fuels are already well underway. The world is currently investing over $1 billion per day in renewable energy sources, particularly wind and solar. Yet despite that investment — over $4 trillion so far — the concentration of atmospheric CO2 is not only rising, it is rising faster than ever.

Part of the problem is that energy policymakers around the world have been focusing on favored generation technologies rather than system-wide solutions.  And because policies and investments have failed to focus on complete solutions, we are inadvertently creating systems that either will not eliminate CO2, or will produce less abundant and less reliable energy.

The solution is to focus on the complete energy system. A clean and effective energy system must meet five critical criteria. The first three are must-haves — essential for an industrial economy. The last two are not essential to the economy but are necessary to preserve the planet we live on.

The must-haves:

1. Abundance. Abundant energy is essential to a thriving economy and happy people. We rely on well-lighted rooms and workspaces, homes that are warm in winter and cool in summer.
2. Reliability. Industrial economies require 24/7 energy, regardless of the weather or demand fluctuation. Reliability is central to national, regional and even global security. As temperature extremes set new global records, reliable heating and air conditioning become critical to life.
3. Affordability. Energy costs affect homeowners and help determine how competitive a nation’s goods are in the global marketplace. We must accurately measure the cost of the system, not just the cost of the energy generator.

And two more criteria that are, in our view, should-haves:

4. Clean. The consequences of global warming, and the health-destroying emissions from burning coal, oil, wood and gas demand that replacement generators and systems be truly clean.
5. Minimal environmental impacts. The health of the planet demands that we pursue technologies and systems with life cycles that minimize environmental impacts to the air, land and oceans.

Traditional fossil-fueled systems meet the first three criteria well. As we transition to clean systems that meet the last two criteria, we must ensure those first three will also (still) be met. Too often, that has not been done and fossil systems have had to fill in.

The analysis of affordability, for example, often focuses only on the cost of the generator. Wind and solar are a case in point. They are, by far, the cheapest way to generate electricity. If the analysis goes no farther, one should expect a solar or wind system to reduce electricity rates.

But the opposite happens in real life. Most jurisdictions that install significant solar resources find their rates go up. Germany and Denmark, two countries with the highest percentage of wind and solar, have seen their rates rise faster than rates in other European countries. California is encountering similar problems.

Looking more closely at solar generators explains why. The best solar farms in Europe or the U.S. produce useful energy less than a quarter of the time (due to night, clouds, winter). Therefore, solar generators need over four times the kilowatt rating (a way of measuring how much power a built plant can produce) to produce the same amount of year-round energy as a coal, gas or nuclear generator.

Moreover, thick clouds can cover whole countries for a week or more, shutting down solar. Batteries are currently far from economical at scale with any known technology. Therefore, utilities need to keep an expensive second power system, usually fossil fueled, online to provide backup energy.

Compared to renewables, nuclear has high upfront costs. But nuclear plants have an 80-year lifespan. Over the lifetime of a nuclear plant, solar or wind plants must be built and rebuilt four times with all the attendant costs and waste. Ultimately, “expensive” nuclear has a much lower total lifetime cost, even when accounting for nuclear waste.

Although we were skeptical at first, after serious investigation and study, we are convinced that clean and reliable nuclear energy meets all five criteria better than any other existing technology. Some see recent news about a canceled small innovative nuclear project as a sign that nuclear is not feasible. Rather, such “weeding out” is to be expected among a field of new startups.

A lot more nuclear energy will be one essential component of new, clean, reliable energy systems.