Using sodium peroxide to scrub carbon dioxide emissions
The problem with carbon capture is not so much that we lack the technology to do it, it's more that we lack the technology to do it in a way that is economically feasible.

Take your example - according to the US Energy Information Adminstration, it takes about 1.09 lbs of coal to generate 1 kWh of electricity. A typical coal-fired plant might produce an average of 500 MW throughout each day (this is a rough estimate), which works out to roughly 12,000 MWh, or 12,000,000 kWh. So that's something like 12 million pounds of coal each day.

If we assume that coal is 100% carbon (close but not quite), then it's about 37.8 mole C per pound of coal. That's 453.6 million moles of carbon each day being converted to $\ce{CO2}$, and since the combustion of carbon follows:

$\ce{C + O2 -&gt; CO2}$

that means a single medium sized-coal plant produces roughly 454 million moles  of $\ce{CO2}$ each day. By now you are probably getting a sense of the scale of this problem. Since sodium peroxide and carbon dioxide have a 1:1 ratio in the absorption equation:

$\ce{2Na2O2 + 2CO2 -&gt; 2Na2CO3 + O2}$

you will need an equal number of moles of sodium peroxide. That works out to about 78 million pounds per day.

Alibaba lists sodium peroxide at around \$400-500 per ton, so that means it would cost you (at a minimum) \$15.6 million dollars per day to scrub the $\ce{CO2}$ emissions from one medium-sized power plant. The real costs would be much higher because of the additional equipment and operating expenses.

Electricity currently sells for about \$0.10 to \$0.20 per kWh in the US, and around half of that is usually for production, with the rest being delivery. That means our 500 MW coal plant is going to be bringing in something like (at the high side) \$1.2 M each day. As you can see, the costs for scrubbing with sodium peroxide far exceed the potential revenue for the plant.

Now, there are other options:

One is to reuse the sodium peroxide, although the costs of regenerating it might exceed just buying more, and you would still need to find a place to store the $\ce{CO2}$.

Another is to use a cheaper/more effective absorbent - according to Wikipedia, amine-gas scrubbing is the most promising technology so far, although I am sure it faces the same kinds of cost scaling problems.

Another more popular approach is carbon capture, where carbon dioxide is basically just pumped into underground reservoirs in the hopes that it will stay there. While this is probably going to turn out to be the most economical approach, it has the risk of releasing large amounts of $\ce{CO2}$ accidentally, as well as having unknown effects on the local geological formations.

Yet another option is to use photosynthesis to scrub carbon dioxide. This has the advantage of being very cheap in comparison to other methods, but the downside is that the rate at which plants and algae can consume $\ce{CO2}$ is much slower than the rate at which we produce it.

It's a big problem, and all of the proposed solutions so far have been very expensive to implement - which is the main reason the fossil fuels industry opposes them.