• Question: How could you re-use wasted energy, such as heat in power stations?

    Asked by Cavan to Tadhg on 14 Jun 2015.
    • Photo: Tadhg O'Donovan

      Tadhg O'Donovan answered on 14 Jun 2015:

      Hi Cavan,

      What a great question – this is something that a lot of engineers are looking at! Firstly power stations are less than 40% efficient and most of the 60% is waste heat – so this is where we need to concentrate our efforts….BUT I think you knew that already 🙂

      I’m not sure there is a single simple answer though. Here are some of the options:
      1) District Heating: This is where the waste heat to pumped as hot water to houses in a nearby community/town/city. So instead of the house burning gas or using electricity for their heating, they can take it directly from the power plant. Sound great right? And there are some great examples of this across the UK. So why don’t we do this all the time? Well the pipe network/infrastructure is expensive and for it to work, we’d all need to live close to a power plant and people don’t generally like living close to power plants
      2) Better turbines/electrical generators: To generate electricity, we generally burn gas or coal to create high pressure steam. The high pressure steam then passes through a turbine to generate electricity. One of the reasons our efficiency is low, is that the steam needs to be “dry” (or hot) when it goes through the turbine or it will damage it. I know of some engineers who are developing tougher and cleverer turbines to handle “wet” (cooler) steam and improve efficiency overall.
      3) Other uses: Heat can be used by industry – so we need to locate more manufacturing plants near power generation. Heat can also be used for refrigeration (sounds crazy – but true), sterilisation etc etc). We just need to think creatively and in a “joined-up” manner.

      BUT – what I should say is that we need more renewable energy sources, where we all create our own power (electricity and heat) in our homes and communities! Over 70% of our domestic energy bills are for heating – so time to invest in solar thermal panels.

      Okay – so that answer was longer than I meant it to be….sorry, hope there is something in there for you.

      Tadhg

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