The ground as a HVAC battery: An interview with Kevin Stickney of Erda Energy

The ground as a HVAC battery: An interview with Kevin Stickney of Erda Energy
Courtesy of Erda Energy

Erda Energy is a company that is developing GeoExchange technology which uses the energy of the earth to save energy in heating buildings and drastically reduce their carbon impact. The company believes this technology could help lead Britain to a zero-carbon future, and could be a revolutionary innovation in heating. Erda’s technology uses the ground as a heating and cooling ‘battery’ that never loses its charge. Geoexchange has already been deployed in the UK and the company claims it can help retail stores, hospitals, universities and communities to cut its annual HVAC energy usage by an average of 80 percent.

REM talked to Erda Energy Managing Director Kevin Stickney to find out more.

Can you tell me more about Erda Energy and what it does?

We specialise in the heating and cooling side, we have some particular technologies in the geoexchange area, so the cornerstone of what we do is to use the ground as a source of energy and as a battery to store thermal energy. We’re setting ourselves apart from the more familiar ground source heat pump side of the market. We think you get far more effective and efficient systems if you use them in both heating and cooling mode and we can also capture lots of waste energy that would otherwise go straight into the atmosphere. So Geoexchange makes the most of heating and cooling.

Can you tell me what Geoexchange is and what it does?

As the name suggests, we’re using the ground to exchange energy. What we would typically do is extract energy from the ground to provide heating, across those wintry months of the year. We would then be looking to make the ground cool or cold, ready for summer. We then connect to air conditioning or some sort of process cooling system and then for those months of the year replacing the cold with warm, basically. It’s a kind of virtuous cycle throughout the year. We’re making the ground cool, so we can provide efficient air conditioning in summer and then once we’ve used all that cool in the ground, we then try to warm that ground up by the end of the summer, such that it has a surplus of warmth in it, to use for heating over the winter. If we get our sums right and our control algorithms right, the system can manage itself and go through the annual cycle. That means we can get the best efficiency for heating and for cooling.

What is involved in that process? The mechanics of it?

It is based on heat pumps, so in winter we use heat pumps to provide space heating, hot water, pulling energy out of the water, putting that water into the ground, taking energy out of the ground. It’s a mixture of using the ground as a battery or using it as a renewable source as well. So, taking energy out with a heat pump and putting it into a building, that leaves the ground cold. Then when the building needs cooling, you have a source of cold water, we have a reservoir of cold energy around our boreholes in the ground. You could put that water directly into the building as chilled water, up to a point when that water will get too warm when you start using mechanical chillers as you would normally. We’re trying to make the best of both of those cycles.

Apparently Geoexchange is already being deployed in the UK, whereabouts and what kind of results have you seen?

These systems have been developing for about eight years. We’ve been providing this as a kind of energy-as-a-service, where we’re providing the service for the client, operating the system for the client and making sure it’s efficient. Around the country from Scotland down to Bristol and across to Kent. They all have their different operating requirements.

Are you working anywhere else besides the UK?

We launched in the US last year, during Climate Change Week. We see a lot of similarities [in the US] with the conditions and parameters around where electricity is, where they are with the transport debate, certainly with the likes of California and New York, where they are progressive in their energy grid. We see that as a perfect fit, just like the UK is now, for providing very low-carbon heat. We’re concentrating purely on the UK and the US for the moment, but we have a keen eye on Europe as well. A lot of Europe is a little bit more progressive in terms of using the ground and heat pumps, so yes, we will be looking at that market as well.

What kind of savings in greenhouse gas emissions and energy savings can it generate?

We’ve got live data on our website. We’ve taken real time information from our systems and matched it with real time data from the UK grid. We had the data validated by Professor Alex Rogers at Oxford University. Our carbon saving was 67 percent compared to a traditional gas boiler. With heat pump-based heating and cooling, you can achieve some pretty good carbon savings. On the heating side, we saved 81 percent of the energy. Oxford University also validated some of the algorithms we use on our website to calculate the numbers we put on the website.

What kind of financial savings can the system generate?

At the moment we’ve put this system out there as an energy-as-a-service, where we pay for the system, put in there and then charge the client ongoing payment for the energy that they receive. The money the client is spending is less than the client would have done, because of our efficiency savings. What we’ve seen in buildings is, a typical supermarket you would see payback in under five years, typically after that a five to ten year payback.

How do you think the use of this technology will grow over the next five years or so?

Heat pumps in the UK are being particularly slow to take off. When you use it as ground source, it isn’t particularly effective. When you use it for heating and cooling, it becomes a more attractive proposition. Financially it’s more attractive. We’ve adapted our borehole technology from the oil and gas industry. They are bigger, carry more fluid, and we can also, because of the particular construction techniques that we use for these, retrofit projects. Out of half the projects that we’ve done, about half of them have been retrofit. The technology’s proven, we’ve got all the data behind it, there’s the different elements we’re dealing with, we’re trying to position ourselves to really attack the market in the next five years. The conditions for it are going to become more favourable.

For additional information:

Erda Energy

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