Industrial CHP / Chlor-Alkali Industry
PEM Fuel Cell power using hydrogen from industrial chlorine production units
Hydrogen is produced as byproduct in some industrial processes such as chlorine / caustic soda, and sodium chlorate production. These industries are very energy-intensive. PEM fuel cells can be used to convert the released hydrogen back into electricity, reducing the electricity bill for these large production facilities by up to 20 percent. In addition to saving cost, significant emission reduction is achieved, which can go a long way towards meeting environmental conservation goals.
Nedstack: world class in PEM Power Plants
Nedstack’s business is rooted in PEM Power Plants. Since early 2007, Nedstack has gained extensive experience operating PEM power plants recovering hydrogen in the field and actively maintains a unique testing facility at a chlorine plant in the Netherlands for qualifying new products.
High fuel conversion efficiency
PEM power plants achieve an electric system efficiency of around 50% (LHV) at their nominal operating point, while this efficiency even increases at part load. In contrast, gasoline engine generators can reach 44% electric efficiency at their optimal point of operation, but show a sharp decrease in efficiency at part load. Overall energy efficiencies above 85% can be reached in fuel cell systems by integrating the generated heat, for example by pre-heating the brine of the existing chlor-alkali process to up to 65°C.
High reliability and durability
Whereas Alkaline Fuel Cells (AFC) are extremely sensitive to carbon dioxide poisoning, which leads to rapid degradation of their performance, Nedstack PEM fuel cells are highly reliable and withstand the demands of an industrial environment. The lifetime of our stacks in industrial conditions has proven to exceed 20,000 hours. Our XXL stacks installed in a power plant have been in operation, without any intervention, for over 25,000 hrs. The degradation level of the latest stack generation indicates an economic stack life approaching 40,000hrs.
Low maintenance frequency/costs
PEM fuel cells require no maintenance. Nedstack fuel cells can be equipped with a cell voltage monitoring (CVM) system, which allows an operator to remotely check the stack status in detail. Even the Balance of Plant (BOP) systems need very little maintenance: a regular inspection is sufficient. The proprietary system design and choice of industrial components result in a minimal maintenance requirement proven during 10 years of continuous operation.
Combustion engines can be used to generate electricity from by-product hydrogen. However, the energy efficiency of an Internal Combustion Engine is much lower than that of a fuel cell, especially at partial loads. In addition, since these engines operate at high temperature, nitrogen oxides are formed that need to be removed by an exhaust catalyst. Fuel cell technology will only generate heat and ultrapure water as by-products. Both can often be reused in the production process.
Low total cost of ownership
Nedstack’s fuel cell technology already offers a lower cost of ownership than other options, despite potentially higher CAPEX investment. Nedstack fuel cells enable the Chlorine industry to reliably and efficiently convert their surplus hydrogen into electricity. In this way, they reduce their dependence on external electricity and lower their electricity bill by as much as 20%. Thanks to Nedstack’s PEM Power Plant, this can be achieved without adding operational complexity.
Next to unfamiliarity, there is one other aspect slowing down the uptake of fuel cell systems: they still require a higher initial investment (CapEx) than internal combustion engines (ICE) and batteries. At Nedstack, we are working hard to further decrease the cost levels. In the very near future, PEM fuel cell stacks will become economically competitive from the start. That is, the complete supply chain for PEM fuel cells will profit from the recent boost in activities in the fuel cell electric vehicle (FCEV) market.
The benefits of hydrogen recovery
The industrial chemicals chlorine and caustic soda are produced by passing an electric current through a concentrated solution of salt in water. This process is accompanied by the release of hydrogen. The byproduct hydrogen can be converted to electrical power with PEM fuel cells.
If all the hydrogen is converted to electricity, the electricity consumption of the electrolysis plant from the grid is reduced by 20%. Worldwide 50 million tons of chlorine is produced annually. Conversion of all byproduct hydrogen with fuel cells, for the global chlorine production, would yield 3000 MW of continuous power, equivalent to the electricity consumption of 6 million households.
Another industry bound to benefit from hydrogen energy production is the sodium chlorate production. Sodium chlorate is used for the bleaching of pulpwood for paper production. To limit transportation costs, these electrolysis factories are usually located close to saw mills – in remote areas. At these remote locations the by-product hydrogen is often vented as there is no use for it locally. As PEM Power Plants don’t need refueling, operate under a wide range of climate conditions, and require little maintenance, they are excellently suited to help cut the electricity bills and environmental footprint of sodium chlorate production.
Hydrogen produced within this sector could generate 300 MW of electricity with fuel cells, based on 50% conversion efficiency.
Nowadays about 15% of the produced hydrogen is vented to the atmosphere. Fuel cells operating on the vented hydrogen could generate 450 MW of CO2-free power. This is based on a system conversion efficiency of 50%, compared to a fuel efficiency of only 35% for the best combustion engines operating at their optimal production point. The advantages to bring fuel cells to sources of hydrogen such as the chlor-alkali- and chlorate industries are:
- Abundant supply of pure hydrogen at very low cost. Using vented hydrogen is even totally free
- Guaranteed delivery of the generated electricity to the electrolysis factory
- Savings of up to 20% on the electricity bills
- Water generated by the fuel cells can be used in the production process
- Heat generated by the fuel cells can often be used in the production process
- Large scale of the system leads to lower cost per kWh. The preferred size of a PEM fuel cell system is about 2 MW