Marketing ground coupled heat pump (GCHP) technology is more challenging than marketing other renewable energy technologies such as wind, solar PV, solar thermal, hydro-electric dams and biomass. You can walk past 100 buildings, or even past a whole shopping mall that reduces total energy consumption by 40%, 50% and even 60% and there's nothing that would indicate that it's there. At best you might get a hint that it's different if...
Sewage heat recovery doesn't sound very exciting! But it's something most people simply flush down the drain without giving it a thought. After all, it's just waste, right? Well, actually not...it's a pretty valuable energy source / heat sink. Sewage from a building is generally flushed away from toilets, showers, sinks, dishwashers and washing machines at a temperature of about 65° to 75°F (18° to 24°C). That's what is considered a pretty low-grade heat...in fact most people wouldn't think of...
A GHX is not an energy source...it's not like a gas or power line, or even delivered oil or propane. These fuels are delivered to the building and are essentially an infinite energy supply (as long as someone pays the bill). A GHX is very much a storage tank that can be discharged and recharged depending on what is going on in the building it's connected to. When the building is being cooled, the GHX is being recharged with energy...when the building needs heat, the GHX is being discharged. The storage capacity of the GHX is...
If you look for it, you'll find a lot of "waste" heat in some buildings...and owners or tenants are paying a lot of money to get rid of it. At the same time they are paying a lot of money to purchase energy from a utility to heat their building. What a waste! Buildings are used for many different kinds of activities. Many of these activities and the equipment...
Quite a number of years ago I had a couple of hours between meetings in downtown Winnipeg and found myself driving past the Provincial Legislature. I realized that by the time I got back to my office I would only have 20 minutes before I'd have to return downtown for my next meeting...maybe I could stop in and see the newly elected energy minister and talk to him about ground coupled heat pumps. So I went into the Legislature, knocked on his door to see if he had a few minutes to talk...
Determining the equipment capacity for a conventional HVAC system is relatively simple. You only need to calculate the peak heating and cooling loads of the building if the building is connected to the gas grid. Looking up the size of the gas pipe needed to deliver enough energy to the building is as simple as looking it up on a chart supplied by the gas company. Selecting a cooling tower or air cooled chiller can be done from a catalog or supplier's website. There's more work involved in designing the energy source / heat sink for a GCHP system.
You might have been told that if your building is already well insulated and energy efficient there's not much point in considering a GCHP system. There simply wouldn't be a payback because of the cost of installing a GCHP system and GHX is so high that I'd never get a return on my investment. I'd like to dispel that myth!
A lot of people are familiar with district heating systems. Hot water or steam from a central heating plant is pumped through a network of insulated pipes to nearby buildings. Some district heating systems take advantage of heat produced by a combined heat and power (CHP) plant that greatly improves the overall operating efficiency. One of the downsides of conventional hot water or steam distribution systems is that the piping systems are expensive to install becaus they must be well insulated to reduce heat loss to the ground. Hot water / steam systems are not able to take advantage low grade waste heat sources such as
A challenge with a GHX in extreme climates is the imbalance between heating and cooling loads. Unbalanced energy loads require a larger GHX. They cost more to build. They require more space between boreholes or trenches. They don't work as efficiently because the fluid temperature to the heat pumps approaches the upper or lower limits of heat pumps connected to them. The additional construction cost combined with lower operating efficiency makes these projects more difficult to justify to a client.
Building and project developers are all about getting a project from paper to a built reality. And they're about making money on projects. To make a profit, they have to keep an eye on the budget they've been given to work with. Something that adds cost to the project generally has to be balanced by cost saving in another area, or has to provide greater value, or it won't be considered. So how can we, as geothermal designers and contractors, install systems with no additional cost, or add enough value for a developer to consider a GCHP system for a project?
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.