Gas-to-power: What you need to know about converting your business

Mar 30, 2023
Solar Advice
5 min read

Gas-to-power is a cost-effective, clean, and efficient power solution. It’s an energy source that can be part of an off-grid electric solution or provide you with heat or steam for your processes.

With an increasingly unreliable power source, businesses across South Africa must find alternative ways of keeping the lights on. A few years back, many businesses made the immediate jump to diesel engines, which made sense to them at the time.

But loadshedding hours are getting longer, and diesel prices are going up. Furthermore, businesses find it challenging to stick to diesel and still achieve their green targets. For these reasons, diesel generators are becoming more of a burden than a solution. Businesses need a cheaper, sustainable, and greener power generation option: gas-to-power.

What is gas-to-power?

Gas-to-Power (GTP) converts natural or biogas into power (electric, heat, or steam). The conversion to electricity happens either by burning gas and using the heat to turn a turbine, or using gas as fuel to drive an engine, which spins a generator that creates electricity.

Gas generators (GTGs) are either in simple-cycle or combined-cycle configurations. The main difference is that simple-cycle plants use GTGs without heat recovery, while combined-cycle plants recover the waste heat, which can be used either to generate more power or in manufacturing processes requiring heat or hot water to be put through a second generator. To generate additional power, the waste heat from the combine-cycle comes from either the exhaust-gas streams or the jacket water. So naturally, simple-cycle installations have a lower capital cost but are less energy efficient (higher heat rate). In contrast, combined-cycle installations have higher capital costs but higher energy efficiency (lower heat rate).

Replacing your diesel generator with a gas-to-power solution

Diesel and gas are two different technologies. You can’t use gas in a diesel engine or vice versa; the engines are specific to the technology or fuel. You may find duel fuel generators (that can use gas and diesel), but they are more expensive and less efficient. That is because the fuel stock differs in combustibility, viscosity, and density. A generator specific to the fuel stock will better serve you.

In the industry, you will come across two types of gas engines, lean burn and rich burn. A rich burn is similar to a diesel engine in that you can use it for standby power. A rich burn can handle the load variation when you have a lot of machinery and equipment drawing power. A lean burn has a flat, consistent electricity flow or demand curve. A lean burn is suitable for when you don’t have machinery coming in and out of operation.

For example, a batch plant with machinery that operates for 50 minutes, shuts down for 10 minutes, and then starts up again is unsuitable for a lean burn because it isn’t consistent enough. Much like a diesel engine, a rich burn can handle the fluctuations because it has the torque the engine needs to maintain the spikes in electricity and is better suited for standby applications, much like your diesel generator.

The benefits of switching to gas power

Gas power is more efficient than diesel power; efficient in terms of converting fuel into electrical energy. An engine has a general efficiency of 36% to 42% when converting diesel to electric power, depending on the size of the engine. In essence, 58% or more of that energy is lost in the form of heat energy released from the generator. That heat energy can be captured and used.

SolarAfrica offers gas-to-power engines and heat recapture solutions; the heat capture can come with a gas engine or use in your operational processes. The solutions are not off the shelf; each is customised according to your circumstances. When you sign up for the service, SolarAfrica technicians will take a look at your operational processes. If you have heat SolarAfrica can recover the heat from the generator and apply it in other processes. The heat can be in the form of steam exhaust or hot air from driers.

Using the heat capture technology from SolarAfrica, you can increase your generator efficiency from 32% to 42% when only using fuel stock to 85% to 92% efficiency. The heat from the gas exhaust is ideal because it is similar to industrial burners and blowers that provide heat.

The size of the engine and airflow will determine how much energy you can transfer in the heat exchanger. When you use heat capture, the amount of waste heat can reduce gas consumption in other processes. CO2 emissions are also lower by around 30%, and the generation plant’s overall efficiency can increase upward of 60%.

Per kW of energy, gas is generally cheaper than diesel. Both fuels have experienced volatility due to the war in Ukraine. Despite the volatility in international gas prices, regulation shields South Africans from that. In South Africa, NERSA determines gas prices, making the gas from Sasol more stable than global prices.

A business on a time-of-use schedule can still benefit from the switch to gas power. A 24-hour operation would ideally use own-generation during peak hours and switch to Eskom during off-peak hours, thereby taking advantage of cheap, clean energy at peak and Eskom’s low rates during off-peak.

Gas-to-power use cases

Gas power and heat recapture solutions apply to several industries, which include:

The future of gas: Biogas

In an upcoming blog we’ll explore biogas as an alternative power solution, how it works and how it can help your business take the next step on its green journey while reducing dependance on the grid.

Here are some fast facts about biogas:

Liquefied natural gas (LNG) and biogas have similar properties, with minor differences. LNG naturally has an element of propane or butane, which is a bit dense and gives natural gas a slightly higher calorific value per cubic metre.
You can use LNG and biogas interchangeably. You won’t need to make any changes to your injectors or nozzles, as the difference in density is not that great.
Switching to biogas is beneficial because it is cleaner than LNG. Eskom-supplied electricity carbon emissions are about 0.97 kg/KWh.
When you switch to natural gas, you reduce emissions by 50%. If you opt for biogas, your emissions will be less than 10% of what Eskom energy emits.
Biogas is easier to produce. You can have a biogas plant on your premises to secure your supplies and lower costs. LNG is a cheap energy source but is subject to international events; Sasol recently had to ask for a 96% price increase due to the war in Ukraine.

We’ll expand on these more in the upcoming blog, so make sure you keep an eye out when we post it.

As a business, you understand the importance of keeping costs low, minimising waste, and adopting clean energy. Switch to a gas solution that can add to your bottom line and reduce your reliance on an expensive, dirty, unreliable national grid. Talk to SolarAfrica about switching to green, viable solutions.

Planning your organisation’s green energy road map is easier than it seems. Fill in our green energy goals questionnaire to identify the right alternative energy solution for your business.