Next week, Americans are being invited to take part in what could become the largest act of civil disobedience against global warming in the country's history. People are protesting at the coal-fired power plant that powers legislators on Capitol Hill in Washington DC.

Cynics may say it's about time Americans joined the action. The fact is that too many Americans have been bamboozled for too long by a campaign of disinformation about the science of climate change. Many still think the whole question of mankind's role in global warming is disputed in scientific circles (I expect the comments beneath this blog will soon demonstrate this point).

Hopefully, that science battle is slowly being won. But now the big greenwash is coming from another direction. Now, we have a technology battle. The people who told us for years how climate change was a myth now say it is all true – but something called "clean coal" can fix it.

It's hard to keep track of the differing organisations behind this. First there was Americans for Balanced Energy Choices. Last year that merged with the Center for Energy and Economic Development to create the American Coalition for Clean Coal Electricity (ACCCE). That body is now headlining as something called America's Power. The one thing they have got is money. Money to try and persuade us that coal is good, coal is green and coal is the solution to America's energy needs.

The ACCCE spent $38m last year buying TV, newspaper and magazine space to persuade Americans that coal can be clean and carbon-free. The money mostly came from its members in the coal mining, transportation and burning industries.

You don't see much coal in these ads, though in December its website did feature some singing lumps of coal called the "clean coal carollers". Sadly they went shy about that and the carollers now seem to be on indeterminate holiday leave.

The money doesn't all go into airtime and column inches, of course. According to SourceWatch, almost $1m goes to pay the salary of its president and chief executive officer Stephen L Miller.

But the big PR question, the one that must earn Miller his remuneration, is how to rationalise this oxymoron "clean coal". How to square this carefully created image with inconvenient facts about the fuel's huge carbon footprint – greater than other fossil fuels such as oil and natural gas.

The genius is that they don't really try. Blink and you might miss it. That word "clean" is highly flexible. It can mean what you want it to mean. So for instance, ACCCE claims that modern coal power plants are "70% cleaner".

It sounds good. It sounds like coal really is cleaning up. Perhaps the greenies are behind the times. Call off the demo. But check more closely and you'll notice that the ACCCE doesn't mention which gases are covered by this claim. In fact, the industry has cut emissions of sulphur dioxide and nitrogen oxides under acid-rain legislation enacted years ago. That's what the 70% refers to. But it has not cut planet-warming carbon dioxide emissions.

Its other key strategy is to promote carbon capture and storage (CCS). That is, the idea of catching carbon dioxide before it goes up the stack of a power plant, and burying it out of harm's way underground – forever. It promotes the idea and not the technology, because there is currently no such technology.

But ACCCE has faith. It doesn't argue that CCS can solve coal's environment problems. If it did, it might have to defend its case. Instead, it says "we believe that American can continue to make great progress in improving environmental quality while at the same time enjoying the benefits from using domestic energy sources like coal … In a word: we believe in technology." Good for them, but technologists generally rely on more than faith.

As I have reported here before, this technology is scientifically conjectural, especially at the storage end. And even on an optimistic view of its feasibility, it is at least two decades and several tens of billions of research and development dollars away from actual commercial operation on any scale. Don't take my word for it. Check out the Massachusetts Institute of Technology's study on the matter. Or this study by the International Energy Agency. Bear in mind these reports were written before the US government last year pulled out of FutureGen, its only large-scale R&D programme for carbon-capture technology.

An industry confident of the technology's future might have been expected to plug the funding gap and keep right on going. But not so far. An analysis of ACCCE's members in December by the Center for American Progress found that their total investment in R&D for carbon capture and storage in recent years added up to a total of $3.5bn, compared with profits for one year of $57bn. Sorry, but belief isn't enough. Put up or shut up.

They should be laughed out of court. But what is most worrying is the political traction the clean-coal story is gaining. Sadly, President Obama may be part of the faith brigade. During the election campaign last year, he was quoted telling the people of Michigan that "you can't tell me we can't figure out how to burn coal that we mine right here in the USA and make it work."

It's not a great quote, but it's the best the ACCCE could come up with, and they have run ads with it.

The trouble with CCS right now is that it is being sold as an imminent fix when it is very far from that. And it is being sold as a reason to carry on supporting the coal industry. After all, the argument runs, if we pull the plug on new coal-fired power plants now, then how will they fund the R&D that could deliver clean coal one day?

That is a very dangerous argument indeed. It is the reason why Nasa climate scientist James Hansen is supporting the demonstration in DC, and insists that no new coal-fired power stations should be built unless and until all their carbon dioxide can be captured and buried forever.

Sadly, for too many policy-makers, the idea that we can have coal and tackle climate change at the same time is too good to miss. Sadly, it is too good to be true.

• How many more green scams, cons and generous slices of wishful thinking are out there? Please email your examples of greenwash to greenwash@theguardian.com or add your comments below