Over the past year, critics of renewable energy have increased the volume and severity of their attacks on the industry, claiming thatsolar wind, geothermal and even efficiency as a concept are expensive, inefficient pipe dreams.

So what has happened in conventional energy?

--In Fukushima, Japan, a nuclear accident of epic proportions continues to spew radioactive material that will likely turn a populated area over 20 miles in diameter into a quarantine zone for years. Reports indicate that Tokyo Electric waited for a day before flooding the reactors with seawater “because it was concerned about harming its long-term investment in the plant” according to a Bloomberg story citing the WSJ.

--The Gulf oil spill last year in the U.S. killed 11 and will likely result in hundreds of billions of dollars in damages, a total that will include cleanup costs as well as revenue and jobs lost as a result of a downturn in tourism and fishing.  A presidential commission found that BP was aware of problems with the cement poured by Halliburton as far back as 2007.

"The sad fact is that this was an entirely preventable disaster," said Fred Bartlit, chief counsel on the commission.

--Twenty-nine died in an explosion in the Upper Big Branch Mine in West Virginia last year after a methane buildup in the coal mine. Investigations continue, but the head of security for the mine has been indicted for obstructing the investigation.

“Since April 2009, federal regulators have cited the mine eight times for “substantial” violations relating to the mine’s methane control plans, according to the records,” according to a report in the New York Times.

Meanwhile, 29 coal miners died in the Pike River explosions in New Zealand last November, while this week, 45 died in a coal mining accident in Pakistan.

--A gas line in San Bruno, California exploded last September, incinerating a neighborhood and killing eight. Investigations are underway, but it appears that the pipe contained flawed seam welds in other places.

What do all of these incidents share in common? First, you can’t underestimate the dangers of conventional energy. Things explode. Radiation lingers for years. Getting coal and oil involves sending employees and equipment into extreme environments and pushing the limits of even state-of-the-art technology. In the Gulf, some wells drill 35,000 feet deep, a veritable underwater Everest.

But more importantly, all of these accidents seem to have been exacerbated by increasing risk in the face of forgetfulness and negligence. That’s the real story here: humans screw up on a fairly regular basis. When faced with a choice between courting catastrophe and delaying a project or missing a deadline, companies and their employees regularly cut corners and hope for the best.

The Johnstown Flood. The Triangle Shirtwaist Factory Fire. The Ludlow Massacre. Doing a half-assed job with devastating consequences is practically an American tradition.

Solar and wind have their share of accidents, too. Silane (a key chemical for solar cells) explosions have killed 10 over the last 20 years, according to Scientific American, and others have noted that solar manufacturers pollute streams and natural waterways in China. Solar installers have also been killed or injured falling off roofs. Approximately 46 people in all have been killed as the result of the wind industry over the last few decades. Twenty-three died during construction. Only four members of the public, including one woman who parachuted into a turbine, have died.

The key difference here is that it is more difficult to set off cataclysmic chain reactions in the realm of renewables. An installer falling off a roof can’t cause a mine shaft to collapse. Here's a simple quiz: would you rather live near a solar farm, or a coal, nuclear or natural gas plant?

What's more, this analysis only takes direct deaths into consideration. Coal mining has been linked to respiratory illness, soil erosion and other problems. No one will ever level a mountain top to build an LED light bulb factory.

Conventional energy, of course, will still be around for a long, long time. Renewables can’t completely replace them. And many sectors, such as U.S. nuclear, have an admirable track record. The debate over renewables, however, often skips over the actual costs and risks.  When you look at the total picture, the argument for expanding renewables is quite compelling. We don't have to move back to stone knives and bearskins, as some critics argue, by going green.

Speed, for instance, favors renewables. The Department of Energy estimates that only 12 gigawatts of new nuclear may come on-line by 2035. Approximately 6 gigawatts of wind and solar went in the ground in the U.S. last year and the number will increase annually. Assuming just moderate growth, the solar, wind and geothermal industries could put 20 times the power capacity in the ground by 2035.

Cost? Renewables do well again. The manufacturing cost of a solar module has dropped from $21.83 a watt in 1980 to 75 cents a watt this year, mostly because of Moore’s Law-like gains in manufacturing. The cost of oil in the same period has gone from $30 a barrel to over $100 and whipsaws continually because of wars and global demand. U.S. oil reserves can expand, but only as long as oil prices continue to rise. To a petroleum company, 'drill, baby, drill' makes sense at $135 a barrel.

Back to safety: the U.S. only has 104 nuclear reactors and none have been built in decades. What happens will involve new reactors coming out of labs now. Who are the new employees at these reactors and how well will they be trained? What about modular reactors? The law of even slightly larger numbers can start to look ominous.

And make no mistake: accidents cost money. BP and other oil companies are protected by a $75 million liability cap. The Price Anderson Act from the 1950s limits the liability of nuclear power plant owners.

“The nuclear industry in the U.S. has an extremely good record. It can be proud of that,” said Richard Caperton of the Center for American Progress. “But taxpayers will be on the hook for damages. “

We can spend money on building renewable power plants, or spend it later on cleanup.

Pay now or pay later: which do you prefer?