CHP and Trigeneration / District Heat

Let’s look at the problem first, as this may give us an understanding of the solutions we offer. We’re all aware that fossil fuels are both a finite resource which we need to manage with responsibility if we want to keep our world ticking along, but they are also CO2 generators. Releasing CO2 into our environment unchecked is something that we all have come to realise is likely to have a profound and damaging impact on the future of our planet. The cumulative impact of CO2 emissions will increase the so-called greenhouse effect in our atmosphere, raising temperatures, damaging eco-systems, ultimately changing sea levels and generally making our planet a more challenging place for us all to thrive.

The existing problem:

Energy in the UK comes from a variety of sources including nuclear, renewable technologies and direct energy imports, but the bulk of it (a little over 50 percent) is generated by fossil fuel consumption in regional generation centres. Coal or natural gas is burned and the heat from this combustion is used to fire a boiler which produces steam. The steam drives a turbine, and that turbine drives a generator which produces the electrical power.

I’m sure we’ve all seen fossil fuel power stations, and one of the reasons that they’re easy to spot, even though they are almost always in remote locations, is because of the huge plumes of water vapour condensing into the air from the cooling towers of the energy plant. This is a required process in order for the water to be used again to drive the turbines – it doesn’t have enough energy to drive a turbine, so the atmosphere or another method is used to cool it back down to a useable temperature. Some power stations don’t use cooling towers, so they do not have such a dramatic appearance, but they suffer from the same issue in that they need to reduce the energy in that vapour in order for it to be used again.

Even to the casual observer, this seems like a lot of energy that’s going to waste. As with all regional power generation methods, there are significant losses in delivering the energy to the end-user. It’s understandable that people don’t really want to live in the shadow of a power plant, so the energy has to be moved through the National Grid to population centres, and that transport comes with a loss, which can be as much as 11 percent of the total produced.

Some common sense ideas:

If the power was generated locally, the issue of losses during delivery can be practically eliminated, but bringing large power generation facilities into urban areas is not only impractical, but also undesirable. A smaller scale approach is needed.

Thameswey have pioneered the use of efficient, locally generated energy through the use of Combined Hear and Power systems. In a Combined Heat and Power plant (CHP) there are a number of issues addressed. The energy that a traditional generation method wastes as part of the cooling process can be put to use, and the small scale coupled with local delivery mean that additional efficiencies can be gained.

How does it work?

Gas is used to drive a local engine, and this engine drives either a steam turbine or directly drives a generator, producing power. Sometimes these engines are coupled together in order to supply larger demands, but the overall scale is much smaller than traditional methods. The next part of the process is where the efficiencies can be gained. As with any combustion engine, significant amounts of heat will be generated, and under normal conditions this heat is wasted. In a CHP system, that heat is used to generate steam and hot water, which can be used to power other systems within the locality of the station or piped directly to the end user. Specialist super-insulated ducting is installed to link consumer sites to the plant, and these are capable of carrying useable hot water and even cooling to sites nearby.

But you’re still burning fossil fuels?

That is true, but the efficiencies gained through this method of generation and delivery are significant. A regional gas-fired power station can only convert around 40 percent of the energy of the gas burned into usable power. The twin benefits of local delivery and waste heat capture bring CHP facilities to over 80 percent, and this figure can be further improved upon. Some of our plants are Combined Cooling Heat and Power (CCHP) or sometimes called Trigeneration plants. These make further use of the energy that is produced by the engine, but may not be enough to generate steam or hot water directly. This energy can be put to use by means of an absorption chiller as part of the heat engine in order to supply chilled water that can be used in air conditioning, supplied directly to the consumer through a network of insulated local ducting.

The benefits

Because CHP generation is so efficient, Thameswey are able to offer electricity and heating at very competitive prices. As well as enjoying a cost benefit, customers can be confident that the energy that we produce is generated efficiently and comes from a source which minimises environmental and social impacts. Thameswey is leading the way in low carbon, decentralised energy generation, with many projects already delivered and many more underway. It takes consideration, and an eye to the future to see the benefits of this type of energy solution, but it’s one that Thameswey firmly believes in, and will continue to innovate to help us all make better use of the resources we have.