"Smart" metering will mean that in the future when we are short of electricity (and we will be) tarrifs can be adjusted many times during the day so that the price you pay for the electricity you use at any given time of the day (or how windy/sunny it is outside) reflects the amount of electricyty available. Simple supply & demand economics.
The reason we WILL run short of electricity (and personally I can't wait for that to happen) is that no-one is prepared to pay the real cost of power generation, whether that's nuclear, fossil or renewable. The end user will have to pay a lot more for energy in the future if new power generation and transmission infrastructure is going to be built.
The act that no-ne wants to pay for it is perfectly illustrated by today's furore over OFGEM's claim that (once again) energy companies are charging us too much.
You can't have your cake and eat it as they say.