BIG CORRECTION: See below.

General Electric and Hitachi passed one of the key milestones on the long road to deploying a new type of what will arguably be a cheaper and safer nuclear reactor on Wednesday: the submitted for design approval with the Nuclear Regulatory Commission. If they can get design approval secured (the process takes years), a utility that wants to build a plant based on the reactor can then seek approval for a site and, potentially, start to build a nuclear plant with the reactor.

The Economic Simplified Boiling Water Reactor (ESBWR) effectively exploits passive cooling techniques more than older reactors, which means 25 percent fewer pumps and values. Fewer valves means more rapid construction – an entire power plant can be built in 42 months – and at the same time reduces the potential for something to go wrong.

Nuclear appears poised to make a comeback in the U.S. No commercial nuclear plants have been built in the U.S. since the '70s. However, the 104 existing commercial reactor provide 21 percent of the electrical power in the states. Nuclear plants do not emit carbon emissions when operating, but there is that waste problem. Nuclear has also risen in public opinion polls.

A whole host of companies, meanwhile, are developing small modular reactors, fusion reactors and even ones that burn spent nuclear waste (see our guide to new nuclear here). NuScale Power and other new companies are exploiting passive cooling too.

Still, the high costs of reactors, the potential for community opposition, and the long history of delays and cost overruns make both banks and utilities skittish about committing to new nuclear plants.

Correction: I stated in the first version of this that GE and Hitachi got approval. Read the release too fast and got excited. I deeply regret the error.

Advances in lithium chemistry might one day lead to batteries that provide 10 times the performance of existing batteries and cost one-tenth the price, said Winfried Wilcke, IBM Program Director at the Almaden Institute, a two-day conference on energy storage taking place at IBM's Almaden laboratory south of San Jose, Calif.

Improvements in performance by 100 times may not be doable, he added. Unless you are thinking about nuclear batteries.

What are nuclear batteries? They consist of a piece of plutonium wrapped in a thermoelectric material that can convert heat emanating from the plutonium into electricity. (Cypress Semiconductor and a new-spin out from UC Berkeley are two of a small number of companies moving into thermoelectrics.) Wilcke told me he's handled large pieces of plutonium. "It is a hot potato." Nuclear batteries can also be made with capacitors coated to harvest alpha emitters.

Long-range spacecraft rely on nuclear batteries. Past Saturn, it is a necessary source of power.

But for human, everyday use, they would be impractical and un-econonmical for all of the reasons you're thinking of right now.

Nuclear fusion is the ideal energy – it is carbon free, it is virtually limitless, and it creates no nuclear waste.

Too bad it doesn't exist yet.

Still, that isn't stopping people from trying. Earlier this year, Lawrence Livermore National Laboratories showed off a laser system that can potentially squish atoms together with such high intensity that it could set off a fusion reaction. The lab hopes to demonstrate it in 2010 or 2011.

Although national labs likely have a greater chance of demonstrating this, startups are trying too. Tri-Alpha Energy in Southern California has raised VC funds. Canada's General Fusion has as well. General uses a technique called Magnetized Target Fusion (MTF) model. In this scenario, an electric current is generated in a conductive cavity containing lithium and a plasma. The electric current produces a magnetic field and the cavity is collapsed, which results in a massive temperature spike.

The lithium breaks down into helium and tritium. Tritium, an unstable form of hydrogen, is separated and then mixed with deuterium, another form of hydrogen. The two fuse and make helium, a reaction that releases energy that can be harvested. So in short, lithium, a fairly inexpensive and plentiful metal, gets converted to helium in a reaction that generates lots of power and leaves only a harmless gas as a byproduct. MTF has an advantage over other fusion techniques in that the plasma only has to stay at thermonuclear temperatures (150 million degrees Celsius) for a microsecond for a reaction to occur, according to the General Fusion's website and an article I wrote on them in 2008.

They also have a really cool picture of a dinosaur on the website.

Today, Technology Review has a little more on the technology. But one thing that is buried in the article is the whiff of a delay. Back in early 2008, investors said that the company would provide data to show that fusion could be reasonably feasible in three to four years, or two to three years from now.

The company, though, has had a little more trouble than anticipated in raising the funds and now expects to get a prototype plant going within five years, assuming the funds could be had.

So fusion technology appears to be another victim of the credit crunch.

Although the overall growth in capacity for solar and wind are growing faster than the capacity for nuclear or coal, renewables still amount to only a small percentage of the overall power generated.

And solar is still the smallest source of electricity, according to the monthly report from the Energy Information Administration.

In the first four months of the year, the U.S. consumed 1,314,683 million kilowatt hours.

Solar accounted for 205 million kilowatt hours. That's around 0.02 percent when you round up.

Wind accounted for 17,566 million kilowatt hours.  Or 1.3 percent.

Coal came to 658,750 million kilowatt hours, thereby accounting for about 50 percent still.

Nuclear and natural gas are still near the 20 percent mark.

So what does that mean? Huge opportunities for solar installers.

On the liquid fuel side, the U.S. produced 5.3 million barrels of oil a day and 1.8 million barrels a day of natural gas/plant liquid fuel in the first six months of the year. In all, the U.S. consumed around 18.6 million barrels a day. That's down from 19.9 million in 2008 and over 20 million in 2007.

Check out the link.

Duke Energy and Areva will work together to study the feasibility of a nuclear plant in Piketon, Ohio. The announcement was hailed by several politicians in Ohio, including governor Ted Strickland, as a way to produce emission-free energy and jobs in the Midwest.

But don't get too excited yet. The gap between announcing something and actually doing it in nuclear is wide indeed. No nuclear plants have been built in the states since the 1970s. Although the Nuclear Regulatory Commission will  be juggling 17 applications to build 26 new reactors in the U.S., building one takes years. The first four might only be operational by 2016. Four more might come online two years later.

Nuclear plants also cost $6.4 billion (the industry estimate) to $10 billion. Who will pay for it? Where will they be built? Will the public need to subsidize them? If so, why should U.S. taxpayers fund a project partly owned by a French company? These questions will be asked, and we haven't even got to the question of nuclear storage, nuclear waste, and the fact that a large number of the people in the U.S. with nuclear know-how have already passed retirement age.

Some, like Werner Koldehoff, a board member of the German Solar Industry Association, also contend that there is only 30 to 40 years left of available uranium (a contention that is hotly disputed by advocates of fuel recycling and many nuclear experts.)

Those are some of the reasons that most of the new electrical capacity in the U.S. these days comes from renewables.

Still, nuclear provides consistent baseline power, something wind and solar can't do, at least without storage technologies and most mass storage ideas are barely off the drawing board. Nuclear provides 19.4 percent of the power in the U.S. Solar, wind and other new renewables provide 2.5 percent.

It's one of the best debates in green tech.

Where do you stand? More nukes or none? Please write in.

Well, you can't say they didn't try.

House Republicans on Wednesday offered up their own energy bill, one that focuses on building 100 nuclear power plants in the next 20 years and opening oil and gas drilling in offshore regions and the Arctic National Wildlife Refuge, the Associated Press reports.

The American Energy Act, as the bill sponsored by Rep. Mike Pence, R-Ind., is called, does give support for renewable energy with tax credits and funding to be paid through leases from all the proposed oil and gas drilling.

But, unlike the energy and climate bill from Reps. Henry Waxman, D-Calif., and Edward Markey, D-Mass., which includes a controversial cap-and-trade plan to reduce greenhouse-gas emissions, the Republicans' offering says nothing about combating climate change (see House Energy Bill Draft: Cap-and-Trade Included).

As an alternative to the Democrat-sponsored bill now being debated in the House, the Republican alternative stands little chance, of course, given the GOP's lack of votes in Congress.

Republican efforts to make nuclear power plants eligible for energy bill incentives by putting them in the same "low-emissions" class as wind and solar power have been repeatedly blocked in Congress, for example (see Former EPA Chief: Building 100 More Nuclear Reactors is Doable).

The Democratic bill, on the other hand, has been in the works for two months and has the support of President Barack Obama. House Speaker Nancy Pelosi has pledged to bring it to a full House vote in July.

But the proposed cap-and-trade system has faced a spirited backlash from industry and business groups that say it will increase energy costs and harm the economy, which has led to some compromises weakening its original provisions (see Come Get 'Em: Gov't Plans to Give Freebies Under Cap-and-Trade).

And expanding offshore drilling isn't just for Republicans. A Senate committee voted Tuesday to add to the energy and climate bill an amendment, proposed by Sen. Byron Dorgan, D-N.D., that would shrink the buffer zones around Florida's coastline where drilling is prohibited, the Miami Herald reported.

At the same time, however, the Senate Energy and Natural Resources Committee did reject a proposal from Sen. Lisa Murkowski, R-Alaska, to open the arctic wildlife refuge to drilling. 

Babcock & Wilcox, a large energy management company, is getting into the market for small nuclear reactors.

The idea with small nuclear is to tailor the nuclear reactors found on submarines for land use. Hyperion Power Generation, a spin-out of Los Alamos National Labs, and TerraPower, which comes out of Nathan Myhrvold's Intellectual Ventures, are pursuing the same idea. (A more detailed story on TerraPower can be read here.) These companies don't want to put reactors in new subdivisions. Instead, the reactors are buried in concrete deep in the ground at military bases and other secure outposts. Beats using diesel generators.

While TerraPower and Hyperion are staffed and run by experienced nuclear executives, Babcock & Wilson can brag about something else. Namely, that they've been in the nuclear reactor construction business for 50 years. That, and they have lots of money. Nuclear power plants, even small ones, take years to build.

Like it or not, nuclear will likely play a central role in the debate about the global energy future. Applications for around 30 new reactors in the U.S. are expected to be filed in the next few years. Some European countries are re-examining their nuclear policies. And some companies claim they can show that fusion power, which is supposed to be much safer, can become feasible.

Unlike PV panels or wind, nuclear plants can provide large amounts of baseline power consistently. Nuclear plants also don't emit carbon dioxide. But objections remain high, and bomb tests in North Korea do raise questions about how to keep a lid on some of this knowledge. Other critics also question whether nuclear plants can be competitive or whether they will require even larger subsidies than renewables get.

It is one of the most interesting debates in the space.